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Bibliography on: Endosymbiosis

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ESP: PubMed Auto Bibliography 18 Jan 2020 at 01:44 Created: 


A symbiotic relationship in which one of the partners lives within the other, especially if it lives within the cells of the other, is known as endosymbiosis. Mitochondria, chloroplasts, and perhaps other cellular organelles are believed to have originated from a form of endosymbiosis. The endosymbiotic origin of eukaryotes seems to have been a biological singularity — that is, it happened once, and only once, in the history of life on Earth.

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Citations The Papers (from PubMed®)

RevDate: 2020-01-16

Meenatchi R, Thinesh T, Brindangnanam P, et al (2019)

Revealing the impact of global mass bleaching on coral microbiome through 16S rRNA gene-based metagenomic analysis.

Microbiological research, 233:126408 pii:S0944-5013(19)31312-6 [Epub ahead of print].

Coral bleaching, a phenomenon by which the expulsion of corals' alveolate endosymbiont (zooxanthellae) occurs when experiencing thermal stress is the major cause for devastation of corals. However, apart from this obligate symbiont of Scleractinian corals, there are different kinds of microbes that exist as stable, transient or sporadic members of the holobiont which reside within various microhabitats in the coral structures. Thus, this study aims to profile the coral bacterial community composition among different coral genera (thermally-sensitive (Acropora digetifera and A. noblis) and thermally resistant (Favites abdita) coral genera analyzed by field monitoring surveys) and also in a particular coral genus (thermally sensitive coral-A. digetifera) at two different sampling times (March 2016 and January 2017). A total of about 608695 paired end reads were obtained through Illumina MiSeq Sequencing platform. The alpha diversity indices (ACE, Chao1 and Shannon) were found to be higher in A. nobilis, followed by A. digetifera and Favites abdita, and the corresponding Simpson values were also found to follow the same trend, indicating that the samples are both rich in species diversity and species evenness. Proteobacteria was found to be the most dominant phylum and Gammaproteobacteria was the predominant class present in all the coral genera studied as also during different sampling time periods. As Vibrionaceae was previously reported to increase its abundance during bleaching stress conditions, bacterial profiling among different coral genera showed the presence of 86 % Vibrionaceae in A. digetifera colonies, and it was 93 % in A. digetifera samples collected during March 2016 whereas, it was found to decrease significantly (7 %) in same tagged colonies collected during January 2017. Thus, profiling of microbiome is of prime importance while studying the holobiont organism like the corals. Stress levels experienced by Palk Bay are even depicted in this microbiome study showing high alpha diversity indices that should alarm reef managers to pay attention to this precious stress tolerant reef community.

RevDate: 2020-01-16

Zhu YX, Song ZR, Huo SM, et al (2020)

Variation in the microbiome of the spider mite Tetranychus truncatus with sex, instar, and endosymbiont infection.

FEMS microbiology ecology pii:5704398 [Epub ahead of print].

Most arthropod-associated bacterial communities play a crucial role in host functional traits, whose structure could be dominated by endosymbionts. The spider mite Tetranychus truncatus is a notorious agricultural pest harboring various endosymbionts, yet the effects of endosymbionts on spider mite microbiota remain largely unknown. Here, using deep sequencing of the 16S rRNA gene, we characterized the microbiota of male and female T. truncatus with different endosymbionts (Wolbachia and Spiroplasma) across different developmental stages. Although the spider mite microbiota composition varied across the different developmental stages, Proteobacteria were the most dominant bacteria harbored in all samples. Positive relationships among related OTUs dominated the significant coassociation networks among bacteria. Moreover, the spider mites coinfected with Wolbachia and Spiroplasma had a significantly higher daily fecundity and juvenile survival rate than the singly infected or uninfected spider mites. The possible function of spider-mite associated bacteria was discussed. Our results highlight the dynamics of spider mite microbiotas across different life stages, and the potential role of endosymbionts in shaping the microbiota of spider mites and improving host fitness.

RevDate: 2020-01-14

Pettifor BJ, Doonan J, Denman S, et al (2020)

Survival of Brenneria goodwinii and Gibbsiella quercinecans, associated with acute oak decline, in rainwater and forest soil.

Systematic and applied microbiology pii:S0723-2020(19)30347-9 [Epub ahead of print].

Acute oak decline (AOD) affects native UK oak species causing rapid decline and mortality in as little as five years. A major symptom of AOD is black weeping stem lesions associated with bacterial phytopathogens, Brenneria goodwinii and Gibbsiella quercinecans. However, there is limited knowledge on the ecological and environmental reservoirs of these phytopathogens. Rainwater and soils are common reservoirs of plant pathogens in a forest environment; therefore, the aim of this study was to investigate the survival of B. goodwinii and G. quercinecans in vitro when inoculated into rainwater and forest soil using a combination of agar-based colony counts and gyrB gene-targeted quantitative PCR (qPCR). Brenneria goodwinii lost viability on inoculation into soil and rainwater, but was detectable at low abundance in soil for 28 days using qPCR, suggesting a limited ability to persist outside of the host, potentially in a viable but non-culturable (VBNC) state. Conversely, Gibbsiella quercinecans, was re-isolated from rainwater for the entire duration of the experiment (84 days) and was re-isolated from forest soil after 28 days, with qPCR analysis corroborating these trends. These data demonstrate that B. goodwinii is unable to survive in forest soils and rainwater, suggesting that it may be an endosymbiont of oak trees, whereas G. quercinecans remains viable in soil and rainwater biomes, suggesting a broad ecological distribution. These data advance understanding of the potential epidemiology of AOD-associated bacteria and their ecological reservoirs, thus increasing the overall knowledge of the pathology of AOD, which assists the development of future management strategies.

RevDate: 2020-01-10

Goodhead I, Blow F, Brownridge P, et al (2020)

Large-scale and significant expression from pseudogenes in Sodalis glossinidius - a facultative bacterial endosymbiont.

Microbial genomics [Epub ahead of print].

The majority of bacterial genomes have high coding efficiencies, but there are some genomes of intracellular bacteria that have low gene density. The genome of the endosymbiont Sodalis glossinidius contains almost 50 % pseudogenes containing mutations that putatively silence them at the genomic level. We have applied multiple 'omic' strategies, combining Illumina and Pacific Biosciences Single-Molecule Real-Time DNA sequencing and annotation, stranded RNA sequencing and proteome analysis to better understand the transcriptional and translational landscape of Sodalis pseudogenes, and potential mechanisms for their control. Between 53 and 74 % of the Sodalis transcriptome remains active in cell-free culture. The mean sense transcription from coding domain sequences (CDSs) is four times greater than that from pseudogenes. Comparative genomic analysis of six Illumina-sequenced Sodalis isolates from different host Glossina species shows pseudogenes make up ~40 % of the 2729 genes in the core genome, suggesting that they are stable and/or that Sodalis is a recent introduction across the genus Glossina as a facultative symbiont. These data shed further light on the importance of transcriptional and translational control in deciphering host-microbe interactions. The combination of genomics, transcriptomics and proteomics gives a multidimensional perspective for studying prokaryotic genomes with a view to elucidating evolutionary adaptation to novel environmental niches.

RevDate: 2020-01-12

Xiang T, Lehnert E, Jinkerson RE, et al (2020)

Symbiont population control by host-symbiont metabolic interaction in Symbiodiniaceae-cnidarian associations.

Nature communications, 11(1):108.

In cnidarian-Symbiodiniaceae symbioses, algal endosymbiont population control within the host is needed to sustain a symbiotic relationship. However, the molecular mechanisms that underlie such population control are unclear. Here we show that a cnidarian host uses nitrogen limitation as a primary mechanism to control endosymbiont populations. Nitrogen acquisition and assimilation transcripts become elevated in symbiotic Breviolum minutum algae as they reach high-densities within the sea anemone host Exaiptasia pallida. These same transcripts increase in free-living algae deprived of nitrogen. Symbiotic algae also have an elevated carbon-to-nitrogen ratio and shift metabolism towards scavenging nitrogen from purines relative to free-living algae. Exaiptasia glutamine synthetase and glutamate synthase transcripts concomitantly increase with the algal endosymbiont population, suggesting an increased ability of the host to assimilate ammonium. These results suggest algal growth and replication in hospite is controlled by access to nitrogen, which becomes limiting for the algae as their population within the host increases.

RevDate: 2020-01-08

Masson F, Calderon Copete S, Schüpfer F, et al (2020)

Blind killing of both male and female Drosophila embryos by a natural variant of the endosymbiotic bacterium Spiroplasma poulsonii.

Cellular microbiology [Epub ahead of print].

Spiroplasma poulsonii is a vertically transmitted endosymbiont of Drosophila melanogaster that causes male-killing, that is the death of infected male embryos during embryogenesis. Here we report a natural variant of S. poulsonii that is efficiently vertically transmitted yet does not selectively kill males, but kills rather a subset of all embryos regardless of their sex, a phenotype we call "blind-killing". We show that the natural plasmid of S. poulsonii has an altered structure: Spaid, the gene coding for the male-killing toxin, is deleted in the blind-killing strain, confirming its function as a male-killing factor. We then further investigate several hypotheses that could explain the sex-independent toxicity of this new strain on host embryos. As the second non-male-killing variant isolated from a male-killing original population, this new strain raises questions on how male-killing is maintained or lost in fly populations. As a natural knock-out of Spaid, which is unachievable yet by genetic engineering approaches, this variant also represents a valuable tool for further investigations on the male-killing mechanism. This article is protected by copyright. All rights reserved.

RevDate: 2020-01-08

Arab DA, Bourguignon T, Wang Z, et al (2020)

Evolutionary rates are correlated between cockroach symbionts and mitochondrial genomes.

Biology letters, 16(1):20190702.

Bacterial endosymbionts evolve under strong host-driven selection. Factors influencing host evolution might affect symbionts in similar ways, potentially leading to correlations between the molecular evolutionary rates of hosts and symbionts. Although there is evidence of rate correlations between mitochondrial and nuclear genes, similar investigations of hosts and symbionts are lacking. Here, we demonstrate a correlation in molecular rates between the genomes of an endosymbiont (Blattabacterium cuenoti) and the mitochondrial genomes of their hosts (cockroaches). We used partial genome data for multiple strains of B. cuenoti to compare phylogenetic relationships and evolutionary rates for 55 cockroach/symbiont pairs. The phylogenies inferred for B. cuenoti and the mitochondrial genomes of their hosts were largely congruent, as expected from their identical maternal and cytoplasmic mode of inheritance. We found a correlation between evolutionary rates of the two genomes, based on comparisons of root-to-tip distances and on comparisons of the branch lengths of phylogenetically independent species pairs. Our results underscore the profound effects that long-term symbiosis can have on the biology of each symbiotic partner.

RevDate: 2020-01-17

Kaczmarek Ł, Roszkowska M, Poprawa I, et al (2020)

Integrative description of bisexual Paramacrobiotus experimentalis sp. nov. (Macrobiotidae) from republic of Madagascar (Africa) with microbiome analysis.

Molecular phylogenetics and evolution, 145:106730 pii:S1055-7903(19)30499-3 [Epub ahead of print].

In a moss samples collected on Madagascar two populations of Paramacrobiotus experimentalis sp. nov. were found. Paramacrobiotus experimentalis sp. nov. with the presence of a microplacoid and areolatus type of eggs is similar to Pam. danielae, Pam. garynahi, Pam. hapukuensis, Pam. peteri, Pam. rioplatensis and Pam. savai, but it differs from them by some morphological and morphometric characters of the eggs. The p-distance between two COI haplotypes of Pam. experimentalis sp. nov. was 0.17%. In turn, the ranges of uncorrected genetic p-distances of all Paramacrobiotus species available in GenBank was from 18.27% (for Pam. lachowskae) to 25.26% (for Pam. arduus) with an average distance of 20.67%. We also found that Pam. experimentalis sp. nov. is bisexual. This observation was congruent on three levels: (i) morphological - specimen size dimorphism; (ii) structural (primary sexual characteristics) - females have an unpaired ovary while males have an unpaired testis and (iii) molecular - heterozygous and homozygous strains of the ITS-2 marker. Although symbiotic associations of hosts with bacteria (including endosymbiotic bacteria) are common in nature and these interactions exert various effects on the evolution, biology and reproductive ecology of hosts, there is still very little information on the bacterial community associated with tardigrades. To fill this gap and characterise the bacterial community of Pam. experimentalis sp. nov. populations and microbiome of its microhabitat, high throughput sequencing of the V3-V4 hypervariable regions in the bacterial 16S rRNA gene fragment was performed. The obtained 16S rRNA gene sequences ranged from 92,665 to 131163. In total, 135 operational taxonomic units (OTUs) were identified across the rarefied dataset. Overall, both Pam. experimentalis sp. nov. populations were dominated by OTUs ascribed to the phylum Proteobacteria (89-92%) and Firmicutes (6-7%). In the case of samples from tardigrades' laboratory habitat, the most abundant bacterial phylum was Proteobacteria (51-90%) and Bacteroides (9-48%). In all compared microbiome profiles, only 16 of 137 OTUs were shared. We found also significant differences in beta diversity between the partly species-specific microbiome of Pam. experimentalis sp. nov. and its culturing environment. Two OTUs belonging to a putative bacterial endosymbiont were identified - Rickettsiales and Polynucleobacter. We also demonstrated that each bacterial community was rich in genes involved in membrane transport, amino acid metabolism, and carbohydrate metabolism.

RevDate: 2020-01-04

Madhav M, Parry R, Morgan JAT, et al (2020)

Wolbachia endosymbiont of the horn fly Haematobia irritans irritans: a supergroup A strain with multiple horizontally acquired cytoplasmic incompatibility genes.

Applied and environmental microbiology pii:AEM.02589-19 [Epub ahead of print].

The horn fly, Haematobia irritans irritans, is a hematophagous parasite of livestock distributed throughout Europe, Africa, Asia, and the Americas. Welfare losses on livestock due to horn fly infestation are estimated to cost between USD 1-2.5 billion annually in North America and Brazil. The endosymbiotic bacterium Wolbachia pipientis is a maternally inherited manipulator of reproductive biology in arthropods and naturally infects laboratory colonies of horn flies from Kerrville, USA and Alberta, Canada, but has also been identified in wild-caught samples from Canada, USA, Mexico and Hungary. Re-assembly of PacBio long-read and Illumina genomic DNA libraries from the Kerrville H. i. irritans genome project allowed for a complete and circularised 1.3 Mb Wolbachia genome (wIrr). Annotation of wIrr yielded 1249 coding genes, 34 tRNAs, three rRNAs, and five prophage regions. Comparative genomics and whole genome Bayesian evolutionary analysis of wIrr compared to published Wolbachia genomes suggests that wIrr is most closely related to and diverged from Wolbachia supergroup A strains known to infect Drosophila spp. Whole-genome synteny analyses between wIrr and closely related genomes indicates that wIrr has undergone significant genome rearrangements while maintaining high nucleotide identity. Comparative analysis of the cytoplasmic incompatibility (CI) genes of wIrr suggests two phylogenetically distinct CI loci and acquisition of another CifB homolog from phylogenetically distant supergroup A Wolbachia strains suggesting horizontal acquisition of these loci. The wIrr genome provides a resource for future examination of the impact Wolbachia may have in both biocontrol and potential insecticide resistance of horn flies.Importance Horn flies, Haematobia irritans irritans, are obligate hematophagous parasites of cattle having significant effects on production and animal welfare. Control of horn flies mainly relies on the use of insecticides, but issues with resistance have increased interest in development of alternative means of control. Wolbachia pipientis is an endosymbiont bacterium known to have a range of effects on host reproduction such as induction of cytoplasmic incompatibility, feminization, male killing, and also impacts on vector transmission. These characteristics of Wolbachia have been exploited in biological control approaches for a range of insect pests. Here we report the assembly and annotation of the circular genome of the Wolbachia strain of the Kerrville, USA horn fly (wIrr). Annotation of wIrr suggests its unique features including the horizontal acquisition of additional transcriptionally active cytoplasmic incompatibility loci. This study will provide the foundation for future Wolbachia-induced biological effect studies for control of horn flies.

RevDate: 2019-12-27

Aivelo T, Norberg A, B Tschirren (2019)

Bacterial microbiota composition of Ixodes ricinus ticks: the role of environmental variation, tick characteristics and microbial interactions.

PeerJ, 7:e8217.

Ecological factors, host characteristics and/or interactions among microbes may all shape the occurrence of microbes and the structure of microbial communities within organisms. In the past, disentangling these factors and determining their relative importance in shaping within-host microbiota communities has been hampered by analytical limitations to account for (dis)similar environmental preferences ('environmental filtering'). Here we used a joint species distribution modelling (JSDM) approach to characterize the bacterial microbiota of one of the most important disease vectors in Europe, the sheep tick Ixodes ricinus, along ecological gradients in the Swiss Alps. Although our study captured extensive environmental variation along elevational clines, the explanatory power of such large-scale ecological factors was comparably weak, suggesting that tick-specific traits and behaviours, microhabitat and -climate experienced by ticks, and interactions among microbes play an important role in shaping tick microbial communities. Indeed, when accounting for shared environmental preferences, evidence for significant patterns of positive or negative co-occurrence among microbes was found, which is indicative of competition or facilitation processes. Signals of facilitation were observed primarily among human pathogens, leading to co-infection within ticks, whereas signals of competition were observed between the tick endosymbiont Spiroplasma and human pathogens. These findings highlight the important role of small-scale ecological variation and microbe-microbe interactions in shaping tick microbial communities and the dynamics of tick-borne disease.

RevDate: 2020-01-17

Conte CA, Segura DF, Milla FH, et al (2019)

Wolbachia infection in Argentinean populations of Anastrepha fraterculus sp1: preliminary evidence of sex ratio distortion by one of two strains.

BMC microbiology, 19(Suppl 1):289 pii:10.1186/s12866-019-1652-y.

BACKGROUND: Wolbachia, one of the most abundant taxa of intracellular Alphaproteobacteria, is widespread among arthropods and filarial nematodes. The presence of these maternally inherited bacteria is associated with modifications of host fitness, including a variety of reproductive abnormalities, such as cytoplasmic incompatibility, thelytokous parthenogenesis, host feminization and male-killing. Wolbachia has attracted much interest for its role in biological, ecological and evolutionary processes as well as for its potential use in novel and environmentally-friendly strategies for the control of insect pests and disease vectors including a major agricultural pest, the South American fruit fly, Anastrepha fraterculus Wiedemann (Diptera: Tephritidae).

RESULTS: We used wsp, 16S rRNA and a multilocus sequence typing (MLST) scheme including gatB, coxA, hcpA, fbpA, and ftsZ genes to detect and characterize the Wolbachia infection in laboratory strains and wild populations of A. fraterculus from Argentina. Wolbachia was found in all A. fraterculus individuals studied. Nucleotide sequences analysis of wsp gene allowed the identification of two Wolbachia nucleotide variants (named wAfraCast1_A and wAfraCast2_A). After the analysis of 76 individuals, a high prevalence of the wAfraCast2_A variant was found both, in laboratory (82%) and wild populations (95%). MLST analysis identified both Wolbachia genetic variants as sequence type 13. Phylogenetic analysis of concatenated MLST datasets clustered wAfraCast1/2_A in the supergroup A. Paired-crossing experiments among single infected laboratory strains showed a phenotype specifically associated to wAfraCast1_A that includes slight detrimental effects on larval survival, a female-biased sex ratio; suggesting the induction of male-killing phenomena, and a decreased proportion of females producing descendants that appears attributable to the lack of sperm in their spermathecae.

CONCLUSIONS: We detected and characterized at the molecular level two wsp gene sequence variants of Wolbachia both in laboratory and wild populations of A. fraterculus sp.1 from Argentina. Crossing experiments on singly-infected A. fraterculus strains showed evidence of a male killing-like mechanism potentially associated to the wAfraCast1_A - A. fraterculus interactions. Further mating experiments including antibiotic treatments and the analysis of early and late immature stages of descendants will contribute to our understanding of the phenotypes elicited by the Wolbachia variant wAfraCast1_A in A. fraterculus sp.1.

RevDate: 2020-01-08

Sheffer MM, Uhl G, Prost S, et al (2019)

Tissue- and Population-Level Microbiome Analysis of the Wasp Spider Argiope bruennichi Identified a Novel Dominant Bacterial Symbiont.

Microorganisms, 8(1): pii:microorganisms8010008.

Many ecological and evolutionary processes in animals depend upon microbial symbioses. In spiders, the role of the microbiome in these processes remains mostly unknown. We compared the microbiome between populations, individuals, and tissue types of a range-expanding spider, using 16S rRNA gene sequencing. Our study is one of the first to go beyond targeting known endosymbionts in spiders and characterizes the total microbiome across different body compartments (leg, prosoma, hemolymph, book lungs, ovaries, silk glands, midgut, and fecal pellets). Overall, the microbiome differed significantly between populations and individuals, but not between tissue types. The microbiome of the wasp spider Argiope bruennichi features a novel dominant bacterial symbiont, which is abundant in every tissue type in spiders from geographically distinct populations and that is also present in offspring. The novel symbiont is affiliated with the Tenericutes, but has low sequence identity (<85%) to all previously named taxa, suggesting that the novel symbiont represents a new bacterial clade. Its presence in offspring implies that it is vertically transmitted. Our results shed light on the processes that shape microbiome differentiation in this species and raise several questions about the implications of the novel dominant bacterial symbiont on the biology and evolution of its host.

RevDate: 2019-12-20

Dietrich EA, Kingry LC, Kugeler KJ, et al (2019)

Francisella opportunistica sp. nov., isolated from human blood and cerebrospinal fluid.

International journal of systematic and evolutionary microbiology [Epub ahead of print].

Two isolates of a Gram-negative, non-spore-forming coccobacillus cultured from the blood and cerebrospinal fluid of immunocompromised patients in the United States were described previously. Biochemical and phylogenetic analyses revealed that they belong to a novel species within the Francisella genus. Here we describe a third isolate of this species, recovered from blood of a febrile patient with renal failure, and formally name the Francisella species. Whole genome comparisons indicated the three isolates display greater than 99.9 % average nucleotide identity (ANI) to each other and are most closely related to the tick endosymbiont F. persica, with only 88.6-88.8 % ANI to the type strain of F. persica. Based on biochemical, metabolic and genomic comparisons, we propose that these three isolates should be recognized as Francisella opportunistica sp. nov, with the type strain of the species, PA05-1188T, available through the Deutsche Sammlung von Mikroorganismen und Zellkulturen (DSM 107100) and the American Type Culture Collection (ATCC BAA-2974).

RevDate: 2020-01-08

Bigiotti G, Pastorelli R, Guidi R, et al (2019)

Horizontal transfer and finalization of a reliable detection method for the olive fruit fly endosymbiont, Candidatus Erwinia dacicola.

BMC biotechnology, 19(Suppl 2):93.

BACKGROUND: The olive fly, Bactrocera oleae, is the most important insect pest in olive production, causing economic damage to olive crops worldwide. In addition to extensive research on B. oleae control methods, scientists have devoted much effort in the last century to understanding olive fly endosymbiosis with a bacterium eventually identified as Candidatus Erwinia dacicola. This bacterium plays a relevant role in olive fly fitness. It is vertically transmitted, and it benefits both larvae and adults in wild populations; however, the endosymbiont is not present in lab colonies, probably due to the antibiotics and preservatives required for the preparation of artificial diets. Endosymbiont transfer from wild B. oleae populations to laboratory-reared ones allows olive fly mass-rearing, thus producing more competitive flies for future Sterile Insect Technique (SIT) applications.

RESULTS: We tested the hypothesis that Ca. E. dacicola might be transmitted from wild, naturally symbiotic adults to laboratory-reared flies. Several trials have been performed with different contamination sources of Ca. E. dacicola, such as ripe olives and gelled water contaminated by wild flies, wax domes containing eggs laid by wild females, cages dirtied by faeces dropped by wild flies and matings between lab and wild adults. PCR-DGGE, performed with the primer set 63F-GC/518R, demonstrated that the transfer of the endosymbiont from wild flies to lab-reared ones occurred only in the case of cohabitation.

CONCLUSIONS: Cohabitation of symbiotic wild flies and non-symbiotic lab flies allows the transfer of Ca. E. dacicola through adults. Moreover, PCR-DGGE performed with the primer set 63F-GC/518R was shown to be a consistent method for screening Ca. E. dacicola, also showing the potential to distinguish between the two haplotypes (htA and htB). This study represents the first successful attempt at horizontal transfer of Ca. E. dacicola and the first step in acquiring a better understanding of the endosymbiont physiology and its relationship with the olive fly. Our research also represents a starting point for the development of a laboratory symbiotic olive fly colony, improving perspectives for future applications of the Sterile Insect Technique.

RevDate: 2020-01-08

Gegner HM, Rädecker N, Ochsenkühn M, et al (2019)

High levels of floridoside at high salinity link osmoadaptation with bleaching susceptibility in the cnidarian-algal endosymbiosis.

Biology open, 8(12):.

Coral reefs are in global decline mainly due to increasing sea surface temperatures triggering coral bleaching. Recently, high salinity has been linked to increased thermotolerance and decreased bleaching in the sea anemone coral model Aiptasia. However, the underlying processes remain elusive. Using two Aiptasia host--endosymbiont pairings, we induced bleaching at different salinities and show reduced reactive oxygen species (ROS) release at high salinities, suggesting a role of osmoadaptation in increased thermotolerance. A subsequent screening of osmolytes revealed that this effect was only observed in algal endosymbionts that produce 2-O-glycerol-α-D-galactopyranoside (floridoside), an osmolyte capable of scavenging ROS. This result argues for a mechanistic link between osmoadaptation and thermotolerance, mediated by ROS-scavenging osmolytes (e.g., floridoside). This sheds new light on the putative mechanisms underlying the remarkable thermotolerance of corals from water bodies with high salinity such as the Red Sea or Persian/Arabian Gulf and holds implications for coral thermotolerance under climate change.This article has an associated First Person interview with the first author of the paper.

RevDate: 2019-12-16

Xu TT, Chen J, Jiang LY, et al (2019)

Diversity of bacteria associated with Hormaphidinae aphids (Hemiptera: Aphididae).

Insect science [Epub ahead of print].

Bacteria are ubiquitous inhabitants of animals. Hormaphidinae is a particular aphid group exhibiting very diverse life history traits. However, the microbiota in this group is poorly known. In the present study, using high-throughput sequencing of bacterial 16S ribosomal RNA gene amplicons, we surveyed the bacterial flora in hormaphidine aphids and explored whether the aphid tribe, host plant and geographical distribution are associated with the distribution of secondary symbionts. The most dominant bacteria detected in hormaphidine species are heritable symbionts. As expected, the primary endosymbiont Buchnera aphidicola is the most abundant symbiont across all species and has cospeciated with its host aphids. Six secondary symbionts were detected in Hormaphidinae. Arsenophonus is widespread in Hormaphidinae species, suggesting the possibility of ancient acquisition of this symbiont. Ordination analyses and statistical tests show that the symbiont composition does not seem to relate to any of the aphid tribes, host plants or geographical distributions, which indicate that horizontal transfers might occur for these symbionts in Hormaphidinae. Correlation analysis exhibits negative interference between Buchnera and coexisting secondary symbionts, while the interactions between different secondary symbionts are complicated. These findings display a comprehensive picture of the microbiota in Hormaphidinae and may be helpful in understanding the symbiont diversity within a group of aphids. This article is protected by copyright. All rights reserved.

RevDate: 2019-12-18

Schausberger P, Gotoh T, Y Sato (2019)

Spider mite mothers adjust reproduction and sons' alternative reproductive tactics to immigrating alien conspecifics.

Royal Society open science, 6(11):191201.

Maternal effects on environmentally induced alternative reproductive tactics (ARTs) are poorly understood but likely to be selected for if mothers can reliably predict offspring environments. We assessed maternal effects in two populations (Y and G) of herbivorous arrhenotokous spider mites Tetranychus urticae, where males conditionally express fighting and sneaking tactics in male-male combat and pre-copulatory guarding behaviour. We hypothesized that resident mothers should adjust their reproduction and sons' ARTs to immigrating alien conspecifics in dependence of alien conspecifics posing a fitness threat or advantage. To induce maternal effects, females were exposed to own or alien socio-environments and mated to own or alien males. Across maternal and sons' reproductive traits, the maternal socio-environment induced stronger effects than the maternal mate, and G-mothers responded more strongly to Y-influence than vice versa. G-socio-environments and Y-mates enhanced maternal egg production in both populations. Maternal exposure to G-socio-environments demoted, yet maternal Y-mates promoted, guarding occurrence and timing by sons. Sneakers guarded earlier than fighters in Y-environments, whereas the opposite happened in G-environments. The endosymbiont Cardinium, present in G, did not exert any classical effect but may have played a role via the shared plant. Our study highlights interpopulation variation in immediate and anticipatory maternal responses to immigrants.

RevDate: 2020-01-08

Thompson MC, Feng H, Wuchty S, et al (2019)

The green peach aphid gut contains host plant microRNAs identified by comprehensive annotation of Brassica oleracea small RNA data.

Scientific reports, 9(1):18904.

Like all organisms, aphids, plant sap-sucking insects that house a bacterial endosymbiont called Buchnera, are members of a species interaction network. Ecological interactions across such networks can result in phenotypic change in network members mediated by molecular signals, like microRNAs. Here, we interrogated small RNA data from the aphid, Myzus persicae, to determine the source of reads that did not map to the aphid or Buchnera genomes. Our analysis revealed that the pattern was largely explained by reads that mapped to the host plant, Brassica oleracea, and a facultative symbiont, Regiella. To start elucidating the function of plant small RNA in aphid gut, we annotated 213 unique B. oleracea miRNAs; 32/213 were present in aphid gut as mature and star miRNAs. Next, we predicted targets in the B. oleracea and M. persicae genomes for these 32 plant miRNAs. We found that plant targets were enriched for genes associated with transcription, while the distribution of targets in the aphid genome was similar to the functional distribution of all genes in the aphid genome. We discuss the potential of plant miRNAs to regulate aphid gene expression and the mechanisms involved in processing, export and uptake of plant miRNAs by aphids.

RevDate: 2019-12-28

Brumin M, Lebedev G, Kontsedalov S, et al (2019)

Levels of the endosymbiont Rickettsia in the whitefly Bemisia tabaci are influenced by the expression of vitellogenin.

Insect molecular biology [Epub ahead of print].

Bacterial endosymbionts play essential roles in the biology of their arthropod hosts by interacting with internal factors in the host. The whitefly Bemisia tabaci is a worldwide agricultural pest and a supervector for more than 100 plant viruses. Like many other arthropods, Be. tabaci harbours a primary endosymbiont, Porteira aleyrodidarum, and an array of secondary endosymbionts that coexist with Portiera inside bacteriocyte cells. Unlike all of the other secondary symbionts that infect Be. tabaci, Rickettsia has been shown to be an exception by infecting insect organs and not colocalizing with Portiera, and has been shown to significantly impact the insect biology and its interactions with the environment. Little is known about the molecular interactions that underlie insect-symbiont interactions in general, and particularly Be. tabaci-Rickettsia interactions. Here we performed transcriptomic analysis and identified vitellogenin as an important protein that influences the levels of Rickettsia in Be. tabaci. Vitellogenin expression levels were lower in whole insects, but higher in midguts of Rickettsia-infected insects. Immunocapture-PCR assay showed interaction between vitellogenin and Rickettsia, whereas silencing of vitellogenin resulted in nearly complete disappearance of Rickettsia from midguts. Altogether, these results suggest that vitellogenin plays an important role in influencing the levels of Rickettsia in Be. tabaci.

RevDate: 2019-12-18

Benítez-Malvido J, Giménez A, Graciá E, et al (2019)

Impact of habitat loss on the diversity and structure of ecological networks between oxyurid nematodes and spur-thighed tortoises (Testudo graeca L.).

PeerJ, 7:e8076.

Habitat loss and fragmentation are recognized as affecting the nature of biotic interactions, although we still know little about such changes for reptilian herbivores and their hindgut nematodes, in which endosymbiont interactions could range from mutualistic to commensal and parasitic. We investigated the potential cost and benefit of endosymbiont interactions between the spur-thighed tortoise (Testudo graeca L.) and adult oxyurid nematodes (Pharyngodonidae order Oxyurida) in scrublands of southern Spain. For this, we assessed the association between richness and abundance of oxyurid species with tortoises' growth rates and body traits (weight and carapace length) across levels of habitat loss (low, intermediate and high). Furthermore, by using an intrapopulation ecological network approach, we evaluated the structure and diversity of tortoise-oxyurid interactions by focusing on oxyurid species infesting individual tortoises with different body traits and growth rates across habitats. Overall, tortoise body traits were not related to oxyurid infestation across habitats. Oxyurid richness and abundance however, showed contrasting relationships with growth rates across levels of habitat loss. At low habitat loss, oxyurid infestation was positively associated with growth rates (suggesting a mutualistic oxyurid-tortoise relationship), but the association became negative at high habitat loss (suggesting a parasitic relationship). Furthermore, no relationship was observed when habitat loss was intermediate (suggesting a commensal relationship). The network analysis showed that the oxyurid community was not randomly assembled but significantly nested, revealing a structured pattern for all levels of habitat loss. The diversity of interactions was lowest at low habitat loss. The intermediate level, however, showed the greatest specialization, which indicates that individuals were infested by fewer oxyurids in this landscape, whereas at high habitat loss individuals were the most generalized hosts. Related to the latter, connectance was greatest at high habitat loss, reflecting a more uniform spread of interactions among oxyurid species. At an individual level, heavier and larger tortoises tended to show a greater number of oxyurid species interactions. We conclude that there is an association between habitat loss and the tortoise-oxyurid interaction. Although we cannot infer causality in their association, we hypothesize that such oxyurids could have negative, neutral and positive consequences for tortoise growth rates. Ecological network analysis can help in the understanding of the nature of such changes in tortoise-oxyurid interactions by showing how generalized or specialized such interactions are under different environmental conditions and how vulnerable endosymbiont interactions might be to further habitat loss.

RevDate: 2020-01-08

Leybourne DJ, Valentine TA, Bos JIB, et al (2020)

A fitness cost resulting from Hamiltonella defensa infection is associated with altered probing and feeding behaviour in Rhopalosiphum padi.

The Journal of experimental biology, 223(Pt 1): pii:jeb.207936.

Many herbivorous arthropods, including aphids, frequently associate with facultative endosymbiotic bacteria, which influence arthropod physiology and fitness. In aphids, endosymbionts can increase resistance against natural enemies, enhance aphid virulence and alter aphid fitness. Here, we used the electrical penetration graph technique to uncover physiological processes at the insect-plant interface affected by endosymbiont infection. We monitored the feeding and probing behaviour of four independent clonal lines of the cereal-feeding aphid Rhopalosiphum padi derived from the same multilocus genotype containing differential infection (+/-) with a common facultative endosymbiont, Hamiltonella defensa Aphid feeding was examined on a partially resistant wild relative of barley known to impair aphid fitness and a susceptible commercial barley cultivar. Compared with uninfected aphids, endosymbiont-infected aphids on both plant species exhibited a twofold increase in the number of plant cell punctures, a 50% reduction in the duration of each cellular puncture and a twofold higher probability of achieving sustained phloem ingestion. Feeding behaviour was also altered by host plant identity: endosymbiont-infected aphids spent less time probing plant tissue, required twice as many probes to reach the phloem and showed a 44% reduction in phloem ingestion when feeding on the wild barley relative compared with the susceptible commercial cultivar. Reduced feeding success could explain the 22% reduction in growth of H. defensa-infected aphids measured on the wild barley relative. This study provides the first demonstration of mechanisms at the aphid-plant interface contributing to physiological effects of endosymbiont infection on aphid fitness, through altered feeding processes on different quality host plants.

RevDate: 2020-01-08

Sato N (2020)

Complex origins of chloroplast membranes with photosynthetic machineries: multiple transfers of genes from divergent organisms at different times or a single endosymbiotic event?.

Journal of plant research, 133(1):15-33.

The paradigm "cyanobacterial origin of chloroplasts" is currently viewed as an established fact. However, we may have to re-consider the origin of chloroplast membranes, because membranes are not replicated by their own. It is the genes for lipid biosynthetic enzymes that are inherited. In the current understandings, these enzymes became encoded by the nuclear genome as a result of endosymbiotic gene transfer from the endosymbiont. However, we previously showed that many enzymes involved in the synthesis of chloroplast peptidoglycan and glycolipids did not originate from cyanobacteria. Here I present results of comprehensive phylogenetic analysis of chloroplast enzymes involved in fatty acid and lipid biosynthesis, as well as additional chloroplast components related to photosynthesis and gene expression. Four types of phylogenetic relationship between chloroplast enzymes (encoded by the chloroplast and nuclear genomes) and cyanobacterial counterparts were found: type 1, chloroplast enzymes diverged from inside of cyanobacterial clade; type 2, chloroplast and cyanobacterial enzymes are sister groups; type 3, chloroplast enzymes originated from homologs of bacteria other than cyanobacteria; type 4, chloroplast enzymes diverged from eukaryotic homologs. Estimation of evolutionary distances suggested that the acquisition times of chloroplast enzymes were diverse, indicating that multiple gene transfers accounted for the chloroplast enzymes analyzed. Based on the results, I try to relax the tight logic of the endosymbiotic origin of chloroplasts involving a single endosymbiotic event by proposing alternative hypotheses. The hypothesis of host-directed chloroplast formation proposes that glycolipid synthesis ability had been acquired by the eukaryotic host before the acquisition of chloroplast ribosomes. Chloroplast membrane system could have been provided by the host, whereas cyanobacteria contributed to the genes for the genetic and photosynthesis systems, at various times, either before or after the formation of chloroplast membranes. The origin(s) of chloroplasts seems to be more complicated than the single event of primary endosymbiosis.

RevDate: 2019-12-07

Li TP, Zhou CY, Zha SS, et al (2019)

Stable Establishment of Cardinium in the Brown Planthopper Nilaparvata lugens despite Decreased Host Fitness.

Applied and environmental microbiology pii:AEM.02509-19 [Epub ahead of print].

The brown planthopper, Nilaparvata lugens (Hemiptera), is a major pest of rice crops in Asia. Artificial transinfections of Wolbachia have recently been used for reducing host impacts, but transinfections have not yet been undertaken with another important endosymbiont, Cardinium This endosymbiont can manipulate the reproduction of hosts through phenotypes such as cytoplasmic incompatibility (CI), which is strong in the related white-backed planthopper, Sogatella furcifera (Hemiptera). Here, we stably infected N. lugens with Cardinium from S. furcifera and showed that it exhibits perfect maternal transmission in N. lugens The density of Cardinium varied across developmental stages and tissues of its transinfected host. Cardinium did not induce strong CI in N. lugens, likely due to its low density in testicles. The infection did decrease fecundity and hatching rate in the transinfected host, but a decrease in fecundity was not apparent when transinfected females mated with Wolbachia infected males. The experiments show the feasibility of transferring Cardinium endosymbionts across hosts, but the deleterious effects of Cardinium on N. lugens limit its potential to spread in wild populations of N. lugens in the absence of strong CI.IMPORTANCE In this study, we established a Cardinium-infected N. lugens line that possessed complete maternal transmission. Cardinium had a widespread distribution in tissues of N. lugens, and this infection can decrease the fecundity and hatching rate of the host. Our findings emphasize the feasibility of transinfection of Cardinium in insects, and this expands the range of endosymbionts that could be manipulated for pest control.

RevDate: 2019-12-18

Bratovanov EV, Ishida K, Heinze B, et al (2019)

Genome Mining and Heterologous Expression Reveal Two Distinct Families of Lasso Peptides Highly Conserved in Endofungal Bacteria.

ACS chemical biology [Epub ahead of print].

Genome mining identified the fungal-bacterial endosymbiosis Rhizopus microsporus-Mycetohabitans (previously Burkholderia) rhizoxinica as a rich source of novel natural products. However, most of the predicted compounds have remained cryptic. In this study, we employed heterologous expression to isolate and characterize three ribosomally synthesized and post-translationally modified peptides with lariat topology (lasso peptides) from the endosymbiont M. rhizoxinica: burhizin-23, mycetohabin-16, and mycetohabin-15. Through coexpression experiments, it was shown that an orphan gene product results in mature mycetohabin-15, albeit encoded remotely from the core biosynthetic gene cluster. Comparative genomics revealed that mycetohabins are highly conserved among M. rhizoxinica and related endosymbiotic bacteria. Gene knockout and reinfection experiments indicated that the lasso peptides are not crucial for establishing symbiosis; instead, the peptides are exported into the environment during endosymbiosis. This is the first report on lasso peptides from endosymbiotic bacteria.

RevDate: 2020-01-08

Chung M, Teigen LE, Libro S, et al (2019)

Drug Repurposing of Bromodomain Inhibitors as Potential Novel Therapeutic Leads for Lymphatic Filariasis Guided by Multispecies Transcriptomics.

mSystems, 4(6):.

To better understand the transcriptomic interplay of organisms associated with lymphatic filariasis, we conducted multispecies transcriptome sequencing (RNA-Seq) on the filarial nematode Brugia malayi, its Wolbachia endosymbiont wBm, and its laboratory vector Aedes aegypti across the entire B. malayi life cycle. In wBm, transcription of the noncoding 6S RNA suggests that it may be a regulator of bacterial cell growth, as its transcript levels correlate with bacterial replication rates. For A. aegypti, the transcriptional response reflects the stress that B. malayi infection exerts on the mosquito with indicators of increased energy demand. In B. malayi, expression modules associated with adult female samples consistently contained an overrepresentation of genes involved in chromatin remodeling, such as the bromodomain-containing proteins. All bromodomain-containing proteins encoded by B. malayi were observed to be upregulated in the adult female, embryo, and microfilaria life stages, including 2 members of the bromodomain and extraterminal (BET) protein family. The BET inhibitor JQ1(+), originally developed as a cancer therapeutic, caused lethality of adult worms in vitro, suggesting that it may be a potential therapeutic that can be repurposed for treating lymphatic filariasis.IMPORTANCE The current treatment regimen for lymphatic filariasis is mostly microfilaricidal. In an effort to identify new drug candidates for lymphatic filariasis, we conducted a three-way transcriptomics/systems biology study of one of the causative agents of lymphatic filariasis, Brugia malayi, its Wolbachia endosymbiont wBm, and its vector host Aedes aegypti at 16 distinct B. malayi life stages. B. malayi upregulates the expression of bromodomain-containing proteins in the adult female, embryo, and microfilaria stages. In vitro, we find that the existing cancer therapeutic JQ1(+), which is a bromodomain and extraterminal protein inhibitor, has adulticidal activity in B. malayi.

RevDate: 2020-01-17

Hotterbeekx A, Raimon S, Abd-Elfarag G, et al (2019)

Onchocerca volvulus is not detected in the cerebrospinal fluid of persons with onchocerciasis-associated epilepsy.

International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases, 91:119-123 pii:S1201-9712(19)30469-2 [Epub ahead of print].

OBJECTIVES: Epidemiological evidence links onchocerciasis with the development of epilepsy. The aim of this study was to detect Onchocerca volvulus microfilariae or its bacterial endosymbiont, Wolbachia, in the cerebrospinal fluid (CSF) of persons with onchocerciasis-associated epilepsy (OAE).

METHODS: Thirteen persons with OAE and O. volvulus skin snip densities of >80 microfilariae were recruited in Maridi County (South Sudan) and their CSF obtained. Cytospin centrifuged preparations of CSF were examined by light microscopy for the presence of O. volvulus microfilariae. DNA was extracted from CSF to detect O. volvulus (O-150 repeat) by quantitative real-time PCR, and Wolbachia (FtsZ gene) by standard PCR. To further investigate whether CSF from onchocerciasis-infected participants could induce seizures, 3- and 7-day old zebrafish larvae were injected with the CSF intracardially and intraperitoneally, respectively. For other zebrafish larvae, CSF was added directly to the larval medium.

RESULTS: No microfilariae, parasite DNA, or Wolbachia DNA were detected in any of the CSF samples by light microscopy or PCR. All zebrafish survived the procedures and none developed seizures.

CONCLUSIONS: The absence of O. volvulus in the CSF suggests that OAE is likely not caused by direct parasite invasion into the central nervous system, but by another phenomenon triggered by O. volvulus infection.

RevDate: 2020-01-08

Vivero RJ, Villegas-Plazas M, Cadavid-Restrepo GE, et al (2019)

Wild specimens of sand fly phlebotomine Lutzomyia evansi, vector of leishmaniasis, show high abundance of Methylobacterium and natural carriage of Wolbachia and Cardinium types in the midgut microbiome.

Scientific reports, 9(1):17746.

Phlebotomine sand flies are remarkable vectors of several etiologic agents (virus, bacterial, trypanosomatid Leishmania), posing a heavy health burden for human populations mainly located at developing countries. Their intestinal microbiota is involved in a wide range of biological and physiological processes, and could exclude or facilitate such transmission of pathogens. In this study, we investigated the Eubacterial microbiome from digestive tracts of Lu. evansi adults structure using 16S rRNA gene sequence amplicon high throughput sequencing (Illumina MiSeq) obtained from digestive tracts of Lu. evansi adults. The samples were collected at two locations with high incidence of the disease in humans: peri-urban and forest ecosystems from the department of Sucre, Colombia. 289,068 quality-filtered reads of V4 region of 16S rRNA gene were obtained and clustered into 1,762 operational taxonomic units (OTUs) with 97% similarity. Regarding eubacterial diversity, 14 bacterial phyla and 2 new candidate phyla were found to be consistently associated with the gut microbiome content. Proteobacteria, Firmicutes, and Bacteroidetes were the most abundant phyla in all the samples and the core microbiome was particularly dominated by Methylobacterium genus. Methylobacterium species, are known to have mutualistic relationships with some plants and are involved in shaping the microbial community in the phyllosphere. As a remarkable feature, OTUs classified as Wolbachia spp. were found abundant on peri-urban ecosystem samples, in adult male (OTUs n = 776) and unfed female (OTUs n = 324). Furthermore, our results provide evidence of OTUs classified as Cardinium endosymbiont in relative abundance, notably higher with respect to Wolbachia. The variation in insect gut microbiota may be determined by the environment as also for the type of feeding. Our findings increase the richness of the microbiota associated with Lu. evansi. In this study, OTUs of Methylobacterium found in Lu. evansi was higher in engorged females, suggesting that there are interactions between microbes from plant sources, blood nutrients and the parasites they transmit during the blood intake.

RevDate: 2020-01-08

Stouthamer CM, Kelly SE, Mann E, et al (2019)

Development of a multi-locus sequence typing system helps reveal the evolution of Cardinium hertigii, a reproductive manipulator symbiont of insects.

BMC microbiology, 19(1):266.

BACKGROUND: Cardinium is an intracellular bacterial symbiont in the phylum Bacteroidetes that is found in many different species of arthropods and some nematodes. This symbiont is known to be able to induce three reproductive manipulation phenotypes, including cytoplasmic incompatibility. Placing individual strains of Cardinium within a larger evolutionary context has been challenging because only two, relatively slowly evolving genes, 16S rRNA gene and Gyrase B, have been used to generate phylogenetic trees, and consequently, the relationship of different strains has been elucidated in only its roughest form.

RESULTS: We developed a Multi Locus Sequence Typing (MLST) system that provides researchers with three new genes in addition to Gyrase B for inferring phylogenies and delineating Cardinium strains. From our Cardinium phylogeny, we confirmed the presence of a new group D, a Cardinium clade that resides in the arachnid order harvestmen (Opiliones). Many Cardinium clades appear to display a high degree of host affinity, while some show evidence of host shifts to phylogenetically distant hosts, likely associated with ecological opportunity. Like the unrelated reproductive manipulator Wolbachia, the Cardinium phylogeny also shows no clear phylogenetic signal associated with particular reproductive manipulations.

CONCLUSIONS: The Cardinium phylogeny shows evidence of diversification within particular host lineages, and also of host shifts among trophic levels within parasitoid-host communities. Like Wolbachia, the relatedness of Cardinium strains does not necessarily predict their reproductive phenotypes. Lastly, the genetic tools proposed in this study may help future authors to characterize new strains and add to our understanding of Cardinium evolution.

RevDate: 2020-01-08

Kamm K, Osigus HJ, Stadler PF, et al (2019)

Genome analyses of a placozoan rickettsial endosymbiont show a combination of mutualistic and parasitic traits.

Scientific reports, 9(1):17561.

Symbiotic relationships between eukaryotic hosts and bacteria range from parasitism to mutualism and may deeply influence both partners' fitness. The presence of intracellular bacteria in the metazoan phylum Placozoa has been reported several times, but without any knowledge about the nature of this relationship and possible implications for the placozoan holobiont. This information may be of crucial significance since little is known about placozoan ecology and how different species adapt to different environmental conditions, despite being almost invariable at the morphological level. We here report on the novel genome of the rickettsial endosymbiont of Trichoplax sp. H2 (strain "Panama"). The combination of eliminated and retained metabolic pathways of the bacterium indicates a potential for a mutualistic as well as for a parasitic relationship, whose outcome could depend on the environmental context. In particular we show that the endosymbiont is dependent on the host for growth and reproduction and that the latter could benefit from a supply with essential amino acids and important cofactors. These findings call for further studies to clarify the actual benefit for the placozoan host and to investigate a possible role of the endosymbiont for ecological separation between placozoan species.

RevDate: 2020-01-03

Lucchetti C, Genchi M, Venco L, et al (2019)

Optimized protocol for DNA/RNA co-extraction from adults of Dirofilaria immitis.

MethodsX, 6:2601-2605.

Dirofilaria immitis, the etiologic agent of canine heartworm disease, like several other filarial nematodes, harbors the bacterial endosymbiont Wolbachia. To investigate metabolic and functional pathways of D. immitis and Wolbachia individually, along with their interactions, the use of both transcriptomic and genome analysis has becoming increasingly popular. Although several commercial kits are available for the single extraction of either DNA or RNA, no specific protocol has been described for simultaneous extraction of DNA and RNA from such a large organism like an adult D. immitis, where female worms generally reach ∼25 cm in length. More importantly, adult worms of D. immitis can only be obtained either through necropsy of experimentally infected dogs or by minimally-invasive surgical heartworm removal of naturally infected dogs. This makes each individual worm sample extremely important. Thus, in the context of a project aimed at the evaluation of both gene expression analysis and Wolbachia population assessment following different treatments, an optimized protocol for co-extraction of DNA and RNA from a single sample of adult D. immitis has been developed. •An optimized method for DNA/RNA co-extraction from large size nematodes using TRIzol® reagent.•Allows maximum exploitation of unique samples as adults of D. immitis.

RevDate: 2019-12-10

Brunoro GVF, Menna-Barreto RFS, Garcia-Gomes AS, et al (2019)

Quantitative Proteomic Map of the Trypanosomatid Strigomonas culicis: The Biological Contribution of its Endosymbiotic Bacterium.

Protist, 170(6):125698.

Strigomonas culicis is a kinetoplastid parasite of insects that maintains a mutualistic association with an intracellular symbiotic bacterium, which is highly integrated into the protist metabolism: it furnishes essential compounds and divides in synchrony with the eukaryotic nucleus. The protist, conversely, can be cured of the endosymbiont, producing an aposymbiotic cell line, which presents a diminished ability to colonize the insect host. This obligatory association can represent an intermediate step of the evolution towards the formation of an organelle, therefore representing an interesting model to understand the symbiogenesis theory. Here, we used shotgun proteomics to compare the S. culicis endosymbiont-containing and aposymbiotic strains, revealing a total of 11,305 peptides, and up to 2,213 proteins (2,029 and 1,452 for wild type and aposymbiotic, respectively). Gene ontology associated to comparative analysis between both strains revealed that the biological processes most affected by the elimination of the symbiont were the amino acid synthesis, as well as protein synthesis and folding. This large-scale comparison of the protein expression in S. culicis marks a step forward in the comprehension of the role of endosymbiotic bacteria in monoxenous trypanosomatid biology, particularly because trypanosomatids expression is mostly post-transcriptionally regulated.

RevDate: 2020-01-03

Bombaça ACS, Brunoro GVF, Dias-Lopes G, et al (2020)

Glycolytic profile shift and antioxidant triggering in symbiont-free and H2O2-resistant Strigomonas culicis.

Free radical biology & medicine, 146:392-401.

During their life cycle, trypanosomatids are exposed to stress conditions and adapt their energy and antioxidant metabolism to colonize their hosts. Strigomonas culicis is a monoxenous protist found in invertebrates with an endosymbiotic bacterium that completes essential biosynthetic pathways for the trypanosomatid. Our research group previously generated a wild-type H2O2-resistant (WTR) strain that showed improved mitochondrial metabolism and antioxidant defenses, which led to higher rates of Aedes aegypti infection. Here, we assess the biological contribution of the S. culicis endosymbiont and reactive oxygen species (ROS) resistance to oxidative and energy metabolism processes. Using high-throughput proteomics, several proteins involved in glycolysis and gluconeogenesis, the pentose phosphate pathway and glutathione metabolism were identified. The results suggest that ROS resistance decreases glucose consumption and indicate that the metabolic products from gluconeogenesis are key to supplying the protist with high-energy and reducing intermediates. Our hypothesis was confirmed by biochemical assays showing opposite profiles for glucose uptake and hexokinase and pyruvate kinase activity levels in the WTR and aposymbiotic strains, while the enzyme glucose-6P 1-dehydrogenase was more active in both strains. Regarding the antioxidant system, ascorbate peroxidase has an important role in H2O2 resistance and may be responsible for the high infection rates previously described for A. aegypti. In conclusion, our data indicate that the energy-related and antioxidant metabolic processes of S. culicis are modulated in response to oxidative stress conditions, providing new perspectives on the biology of the trypanosomatid-insect interaction as well as on the possible impact of resistant parasites in accidental human infection.

RevDate: 2019-11-21

López-Madrigal S, EH Duarte (2019)

Titer regulation in arthropod-Wolbachia symbioses.

FEMS microbiology letters pii:5637388 [Epub ahead of print].

Symbiosis between intracellular bacteria (endosymbionts) and animals are widespread. The alphaproteobacterium Wolbachia pipientis is known to maintain a variety of symbiotic associations, ranging from mutualism to parasitism, with a wide range of invertebrates. Wolbachia infection might deeply affect host fitness (e.g. reproductive manipulation, antiviral protection), which is thought to explain its high prevalence in nature. Bacterial loads significantly influence both the infection dynamics and the extent of bacteria-induced host phenotypes. Hence, fine regulation of bacterial titers is considered as a milestone in host-endosymbiont interplay. Here we review both environmental and biological factors modulating Wolbachia titers in arthropods.

RevDate: 2019-12-07

Shan HW, Luan JB, Liu YQ, et al (2019)

The inherited bacterial symbiont Hamiltonella influences the sex ratio of an insect host.

Proceedings. Biological sciences, 286(1915):20191677.

In many intracellular symbioses, the microbial symbionts provide nutrients advantageous to the host. However, the function of Hamiltonella defensa, a symbiotic bacterium localized in specialized host cells (bacteriocytes) of a whitefly Bemisia tabaci, is uncertain. We eliminate this bacterium from its whitefly host by two alternative methods: heat treatment and antibiotics. The sex ratio of the host progeny and subsequent generations of Hamiltonella-free females was skewed from 1 : 1 (male : female) to an excess of males, often exceeding a ratio of 20 : 1. B. tabaci is haplodiploid, with diploid females derived from fertilized eggs and haploid males from unfertilized eggs. The Hamiltonella status of the insect did not affect copulation frequency or sperm reserve in the spermathecae, indicating that the male-biased sex ratio is unlikely due to the limitation of sperm but likely to be associated with events subsequent to sperm transfer to the female insects, such as failure in fertilization. The host reproductive response to Hamiltonella elimination is consistent with two alternative processes: adaptive shift in sex allocation by females and a constitutive compensatory response of the insect to Hamiltonella-mediated manipulation. Our findings suggest that a bacteriocyte symbiont influences the reproductive output of female progeny in a haplodiploid insect.

RevDate: 2020-01-08

Li Y, Tassia MG, Waits DS, et al (2019)

Genomic adaptations to chemosymbiosis in the deep-sea seep-dwelling tubeworm Lamellibrachia luymesi.

BMC biology, 17(1):91.

BACKGROUND: Symbiotic relationships between microbes and their hosts are widespread and diverse, often providing protection or nutrients, and may be either obligate or facultative. However, the genetic mechanisms allowing organisms to maintain host-symbiont associations at the molecular level are still mostly unknown, and in the case of bacterial-animal associations, most genetic studies have focused on adaptations and mechanisms of the bacterial partner. The gutless tubeworms (Siboglinidae, Annelida) are obligate hosts of chemoautotrophic endosymbionts (except for Osedax which houses heterotrophic Oceanospirillales), which rely on the sulfide-oxidizing symbionts for nutrition and growth. Whereas several siboglinid endosymbiont genomes have been characterized, genomes of hosts and their adaptations to this symbiosis remain unexplored.

RESULTS: Here, we present and characterize adaptations of the cold seep-dwelling tubeworm Lamellibrachia luymesi, one of the longest-lived solitary invertebrates. We sequenced the worm's ~ 688-Mb haploid genome with an overall completeness of ~ 95% and discovered that L. luymesi lacks many genes essential in amino acid biosynthesis, obligating them to products provided by symbionts. Interestingly, the host is known to carry hydrogen sulfide to thiotrophic endosymbionts using hemoglobin. We also found an expansion of hemoglobin B1 genes, many of which possess a free cysteine residue which is hypothesized to function in sulfide binding. Contrary to previous analyses, the sulfide binding mediated by zinc ions is not conserved across tubeworms. Thus, the sulfide-binding mechanisms in sibgolinids need to be further explored, and B1 globins might play a more important role than previously thought. Our comparative analyses also suggest the Toll-like receptor pathway may be essential for tolerance/sensitivity to symbionts and pathogens. Several genes related to the worm's unique life history which are known to play important roles in apoptosis, cell proliferation, and aging were also identified. Last, molecular clock analyses based on phylogenomic data suggest modern siboglinid diversity originated in 267 mya (± 70 my) support previous hypotheses indicating a Late Mesozoic or Cenozoic origins of approximately 50-126 mya for vestimentiferans.

CONCLUSIONS: Here, we elucidate several specific adaptations along various molecular pathways that link phenome to genome to improve understanding of holobiont evolution. Our findings of adaptation in genomic mechanisms to reducing environments likely extend to other chemosynthetic symbiotic systems.

RevDate: 2019-11-18

Foo E, Plett JM, Lopez-Raez JA, et al (2019)

Editorial: The Role of Plant Hormones in Plant-Microbe Symbioses.

Frontiers in plant science, 10:1391.

RevDate: 2019-11-15

Richardson LGL, DJ Schnell (2019)

Origins, function and regulation of the TOC-TIC general protein import machinery of plastids.

Journal of experimental botany pii:5626434 [Epub ahead of print].

The evolution of chloroplasts from the original endosymbiont involved the transfer of thousands of genes from the ancestral bacterial genome to the host nucleus, thereby combining the two genetic systems to facilitate coordination of gene expression and achieve integration of host and organelle functions. A key element of successful endosymbiosis was the evolution of a unique protein import system to selectively and efficiently target nuclear-encoded proteins to their site of function within the chloroplast after synthesis in the cytoplasm. The chloroplast TOC-TIC general protein import system is conserved across the plant kingdom, and is a system of hybrid origin, with core membrane transport components adapted from bacterial protein targeting systems, and additional components adapted from host genes to confer the specificity and directionality of import. In vascular plants, the TOC-TIC system has diversified to mediate the import of specific, functionally related classes of plastid proteins. This functional diversification occurred as the plastid family expanded to fulfill cell- and tissue-specific functions in terrestrial plants. In addition, there is growing evidence that direct regulation of TOC-TIC activities plays an essential role in the dynamic remodeling of the organelle proteome that is required to coordinate plastid biogenesis with developmental and physiological events.

RevDate: 2019-11-13

Wang D, C Wei (2019)

Bacterial communities in digestive and excretory organs of cicadas.

Archives of microbiology pii:10.1007/s00203-019-01763-4 [Epub ahead of print].

Bacteriocyte-associated symbionts are essential for the health of many sap-sucking insects, such as cicadas, leafhoppers and treehoppers, etc., but little is known about the bacterial community in the gut and other related organs in these insects. We characterized the bacterial communities in the salivary glands, alimentary canal and the Malpighian tubules of two populations of the cicada Subpsaltria yangi occurring in different habitats and feeding on different hosts. A high degree of similarity of core microbiota was revealed between the two populations, both with the top three bacteria belonging to Meiothermus, Candidatus Sulcia and Halomonas. The bacterial communities in various organs clustered moderately by populations possibly reflect adaptive changes in the microbiota of related S. yangi populations, which provide a better understanding of the speciation and adaptive mechanism of this species to different diets and habitats. When compared with two phylogenetically distant cicada species, Hyalessa maculaticollis and Meimuna mongolica, the core microbiota in S. yangi was significantly different to that of these species. In addition, our results confirm that Ca. Sulcia distributes in the digestive and excretory organs besides the bacteriomes and gonads, which provide potential important information onto the trophic functions of this obligate endosymbiont to the host insects.

RevDate: 2020-01-08
CmpDate: 2019-11-29

Normark BB, Okusu A, Morse GE, et al (2019)

Phylogeny and classification of armored scale insects (Hemiptera: Coccomorpha: Diaspididae).

Zootaxa, 4616(1):zootaxa.4616.1.1 pii:zootaxa.4616.1.1.

Armored scale insects (Hemiptera: Coccomorpha: Diaspididae) are major economic pests and are among the world's most invasive species. Here we describe a system of specimen and identification management that establishes a basis for well-vouchered molecular identification. We also present an expanded Bayesian phylogenetic analysis based on concatenated fragments of 4 genetic loci: the large ribosomal subunit (28S), elongation factor-1 alpha (EF-1α), cytochrome oxidase I and II (COI‒II), and the small ribosomal subunit (16S) of the primary endosymbiont, Uzinura diaspidicola (Bacteroidetes: Flavobacteriales). Our sample includes 1,389 individuals, representing 11 outgroup species and at least 311 described and 61 undescribed diaspidid species. The results broadly support Takagi's 2002 classification but indicate that some revisions are needed. We propose a revised classification recognizing 4 subfamilies: Ancepaspidinae Borchsenius, new rank, Furcaspidinae Balachowsky, new rank, Diaspidinae Targioni Tozzetti, and Aspidiotinae Westwood. Within Aspidiotinae, in addition to the existing tribes Aspidiotini Westwood, Parlatoriini Leonardi, Odonaspidini Ferris, Leucaspidini Atkinson, and Smilacicolini Takagi, we recognize as tribes Gymnaspidini Balachowsky, new rank, and Aonidiini Balachowsky, new rank. Within Diaspidinae we recognize the 2 tribes Lepidosaphidini Shimer and Diaspidini Targioni Tozzetti, and within Diaspidini we recognize three subtribes: Diaspidina Targioni Tozzetti, Fioriniina Leonardi, and Chionaspidina Brues Melander. We regard Kuwanaspidina Borchsenius as a junior synonym of Fioriniina, Thysanaspidini Takagi as a junior synonym of Leucaspidini, and Protodiaspidina Takagi and Ulucoccinae Takagi as junior synonyms of Chionaspidina. To clarify the composition of the higher taxa we describe 2 new genera for Australian species heretofore misplaced in the genus Ancepaspis Ferris: Brimblecombia Normark (Aonidiini) and Hendersonaspis Normark (Leucaspidini). We also propose many additional minor modifications to the taxonomy of Diaspididae, including the following new combinations, revived combinations, and replacement names: Aonidia edgerleyi (Mamet), new combination (from Bigymnaspis Balachowsky); Aonidomytilus espinosai Porter, revived combination (from Porterinaspis González); Aspidiotus badius (Brain), new combination (this and the next 5 Aspidiotus species all from Aonidia Targioni Tozzetti); Aspidiotus biafrae (Lindinger), new combination; Aspidiotus chaetachmeae (Brain), new combination; Aspidiotus laticornis (Balachowsky), new combination; Aspidiotus rhusae (Brain), new combination; Aspidiotus sclerosus (Munting), new combination; Brimblecombia asperata (Brimblecombe), new combination (this and the next 5 Brimblecombia species all from Ancepaspis); Brimblecombia longicauda (Brimblecombe), new combination; Brimblecombia magnicauda (Brimblecombe), new combination; Brimblecombia reticulata (Brimblecombe), new combination; Brimblecombia rotundicauda (Brimblecombe), new combination; Brimblecombia striata (Brimblecombe), new combination; Cooleyaspis pseudomorpha (Leonardi), new combination (from Dinaspis Leonardi); Cupidaspis wilkeyi (Howell Tippins), new combination (from Paracupidaspis Howell Tippins); Cupressaspis isfarensis Borchsenius, revived combination (this species, the next 2 species in Cupressaspis Borchsenius, revived genus, and the next 9 species in Diaspidiotus Cockerell all from Aonidia); Cupressaspis mediterranea (Lindinger), revived combination; Cupressaspis relicta (Balachowsky), new combination; Diaspidiotus atlanticus (Ferris), new combination; Diaspidiotus marginalis (Brain), new combination; Diaspidiotus maroccanus (Balachowsky), new combination; Diaspidiotus mesembryanthemae (Brain), new combination; Diaspidiotus opertus (De Lotto), new combination; Diaspidiotus shastae (Coleman), new combination; Diaspidiotus simplex (Leonardi), new combination; Diaspidiotus visci (Hall), new combination; Diaspidiotus yomae (Munting), new combination; Diaspis arundinariae (Tippins Howell), new combination (from Geodiaspis Tippins Howell); Duplachionaspis arecibo (Howell), new combination (this and the next 10 Duplachionaspis MacGillivray species all from Haliaspis Takagi); Duplachionaspis asymmetrica Ferris, revived combination; Duplachionaspis distichlii (Ferris), revived combination; Duplachionaspis litoralis Ferris, revived combination; Duplachionaspis mackenziei McDaniel, revived combination; Duplachionaspis milleri (Howell), new combination; Duplachionaspis nakaharai (Howell), new combination; Duplachionaspis peninsularis (Howell), new combination; Duplachionaspis spartinae (Comstock), revived combination; Duplachionaspis texana (Liu Howell) new combination; Duplachionaspis uniolae (Takagi), new combination; Duplachionaspis mutica (Williams) (from Aloaspis Williams), new combination; Epidiaspis doumtsopi (Schneider), new combination (from Diaspis Costa); Fiorinia ficicola (Takahashi), new combination (from Ichthyaspis Takagi); Fiorinia macroprocta (Leonardi), revived combination (this and the next 2 species of Fiorinia Targioni Tozzetti all from Trullifiorinia Leonardi); Fiorinia rubrolineata Leonardi, revived combination; Fiorinia scrobicularum Green, revived combination; Genaparlatoria pseudaspidiotus (Lindinger), revived combination (from Parlatoria); Greeniella acaciae (Froggatt), new combination (this and the next 4 Greeniella Cockerell species all from Gymnaspis Newstead); Greeniella cassida (Hall Williams), new combination; Greeniella grandis (Green), new combination; Greeniella perpusilla (Maskell), new combination; Greeniella serrata (Froggatt), new combination; Hendersonaspis anomala (Green), new combination (from Ancepaspis); Hulaspis bulba (Munting), new combination (this and the next Hulaspis Hall species both from Andaspis MacGillivray); Hulaspis formicarum (Ben-Dov), new combination; Lepidosaphes antidesmae (Rao in Rao Ferris), new combination (this and the next 19 species all from Andaspis); Lepidosaphes arcana (Matile-Ferrero), new combination; Lepidosaphes betulae (Borchsenius), new combination; Lepidosaphes citricola (Young Hu), new combination; Lepidosaphes conocarpi (Takagi), new combination; Lepidosaphes crawi (Cockerell), revived combination; Lepidosaphes erythrinae Rutherford, revived combination; Lepidosaphes incisor Green, revived combination; Lepidosaphes indica (Borchsenius), new combination; Lepidosaphes kashicola Takahashi, revived combination; Lepidosaphes kazimiae (Williams), new combination; Lepidosaphes laurentina (Almeida), new combination; Lepidosaphes maai (Williams Watson), new combination; Lepidosaphes mackieana McKenzie, revived combination; Lepidosaphes micropori (Borchsenius), new combination; Lepidosaphes punicae Laing, revived combination; Lepidosaphes quercicola (Borchsenius), new combination; Lepidosaphes recurrens (Takagi Kawai), new combination; Lepidosaphes viticis (Takagi), new combination; Lepidosaphes xishuanbannae (Young Hu), new combination; Lepidosaphes giffardi (Adachi Fullaway), new combination (from Carulaspis MacGillivray); Lepidosaphes garciniae (Young Hu), new combination (this and the next 2 species all from Ductofrontaspis Young Hu); Lepidosaphes huangyangensis (Young Hu), new combination; Lepidosaphes jingdongensis (Young Hu), new combination; Lepidosaphes recurvata (Froggatt), revived combination (from Metandaspis Williams); Lepidosaphes ficicola Takahashi, revived combination (this and the next 2 species all from Ungulaspis MacGillivray); Lepidosaphes pinicolous Chen, revived combination; Lepidosaphes ungulata Green, revived combination; Lepidosaphes serrulata (Ganguli), new combination (from Velataspis Ferris); Lepidosaphes huyoung Normark, replacement name for Andaspis ficicola Young Hu; Lepidosaphes tangi Normark, replacement name for Andaspis schimae Tang; Lepidosaphes yuanfeng Normark, replacement name for Andaspis keteleeriae Yuan Feng; Leucaspis ilicitana (Gómez-Menor), new combination (from Aonidia); Lopholeucaspis spinomarginata (Green), new combination (from Gymnaspis); Melanaspis campylanthi (Lindinger), new combination (from Aonidia); Mohelnaspis bidens (Green), new combination (from Fiorinia); Parlatoria affinis (Ramakrishna Ayyar), new combination (this and the next 4 Parlatoria species all from Gymnaspis); Parlatoria ficus (Ramakrishna Ayyar), new combination; Parlatoria mangiferae (Ramakrishna Ayyar), new combination; Parlatoria ramakrishnai (Green), new combination; Parlatoria sclerosa (Munting), new combination; Parlatoria bullata (Green), new combination (from Bigymnaspis); Parlatoria leucaspis (Lindinger), new combination (this and the next species both from Cryptoparlatorea Lindinger); Parlatoria pini (Takahashi), new combination; Parlatoria tangi Normark, replacement name for Parlatoria pini Tang; Pseudoparlatoria bennetti (Williams), new combination (from Parlagena McKenzie); Pseudoparlatoria chinchonae (McKenzie), new combination (from Protodiaspis Cockerell); Pseudoparlatoria larreae (Leonardi), revived combination (from Protargionia Leonardi); Quernaspis lepineyi (Balachowsky), new combination (from Chionaspis); Rhizaspidiotus nullispinus (Munting), new combination (from Aonidia); Rolaspis marginalis (Leonardi), new combination (from Lepidosaphes); Salicicola lepelleyi (De Lotto), new combination (from Anotaspis Ferris); Tecaspis giffardi (Leonardi), new combination (from Dinaspis); Trullifiorinia geijeriae (Froggatt), new combination (from Fiorinia); Trullifiorinia nigra (Lindinger), new combination (from Crypthemichionaspis Lindinger); and Voraspis olivina (Leonardi), new combination (from Lepidosaphes).

RevDate: 2020-01-08

Clanner-Engelshofen BM, French LE, M Reinholz (2019)

Corynebacterium kroppenstedtii subsp. demodicis is the endobacterium of Demodex folliculorum.

Journal of the European Academy of Dermatology and Venereology : JEADV [Epub ahead of print].

BACKGROUND: Demodex spp. mites are the most complex member of the human skin microbiome. Mostly they are commensals, although their pathophysiological role in inflammatory dermatoses is recognized. Demodex mites cannot be cultivated in vitro, so only little is known about their life cycle, biology and physiology. Different bacterial species have been suggested to be the endobacterium of Demodex mites, including Bacillus oleronius, B. simplex, B. cereus and B. pumilus.

OBJECTIVES: Our aim was to find the true endobacterium of human Demodex mites.

METHODS: The distinct genetic and phenotypic differences and similarities between the type strain and native isolates are described by DNA sequencing, PCR, MALDI-TOF, DNA-DNA hybridization, fatty and mycolic acid analyses, and antibiotic resistance testing.

RESULTS: We report the true endobacterium of Demodex folliculorum, independent of the sampling source of mites or life stage: Corynebacterium kroppenstedtii subsp. demodicis.

CONCLUSIONS: We anticipate our finding to be a starting point for more in-depth understanding of the tripartite microbe-host interaction between Demodex mites, its bacterial endosymbiont and the human host.

RevDate: 2020-01-08

Igloi GL (2019)

Molecular evidence for the evolution of the eukaryotic mitochondrial arginyl-tRNA synthetase from the prokaryotic suborder Cystobacterineae.

FEBS letters [Epub ahead of print].

The evolutionary origin of the family of eukaryotic aminoacyl-tRNA synthetases that are essential to all living organisms is a matter of debate. In order to shed molecular light on the ancient source of arginyl-tRNA synthetase, a total of 1347 eukaryotic arginyl-tRNA synthetase sequences were mined from databases and analyzed. Their multiple sequence alignment reveals a signature sequence that is characteristic of the nuclear-encoded enzyme, which is imported into mitochondria. Using this molecular beacon, the origins of this gene can be traced to modern prokaryotes. In this way, a previous phylogenetic analysis linking Myxococcus to the emergence of the eukaryotic mitochondrial arginyl-tRNA synthetase is supported by the unique existence of the molecular signature within the suborder Cystobacterineae that includes Myxococcus.

RevDate: 2019-11-22

Hodo CL, Forgacs D, Auckland LD, et al (2020)

Presence of diverse Rickettsia spp. and absence of Borrelia burgdorferi sensu lato in ticks in an East Texas forest with reduced tick density associated with controlled burns.

Ticks and tick-borne diseases, 11(1):101310.

As tick-borne diseases continue to emerge across the United States, there is need for a better understanding of the tick and pathogen communities in the southern states and of habitat features that influence transmission risk. We surveyed questing and on-host ticks in pine-dominated forests with various fire management regimes in the Sam Houston National Forest, a popular recreation area near Houston, Texas. Four linear transects were established- two with a history of controlled burns, and two unburned. Systematic drag sampling yielded 112 ticks from two species, Ixodes scapularis (n=73) and Amblyomma americanum (n=39), with an additional 106 questing ticks collected opportunistically from drag cloth operators. There was a significant difference in systematically-collected questing tick density between unburned (15 and 18 ticks/1000 m2) and burned (2 and 4 ticks/1000 m2) transects. We captured 106 rodents and found 74 ticks on the rodents, predominantly Dermacentor variabilis. One unburned transect had significantly more ticks per mammal than any of the other three transects. DNA of Rickettsia species was detected in 146/292 on and off-host ticks, including the 'Rickettsial endosymbiont of I. scapularis' and Rickettsia amblyommatis, which are of uncertain pathogenicity to humans. Borrelia lonestari was detected in one A. americanum, while Borrelia burgdorferi sensu stricto, the agent of Lyme disease, was not detected in any tick samples. Neither Borrelia nor Rickettsia spp. were detected in any of the mammal ear biopsies (n=64) or blood samples (n=100) tested via PCR. This study documents a high prevalence in ticks of Rickettsia spp. thought to be endosymbionts, a low prevalence of relapsing fever group Borrelia in ticks, and a lack of detection of Lyme disease-group Borrelia in both ticks and mammals in an east Texas forested recreation area. Additionally, we observed low questing tick density in areas with a history of controlled burns. These results expand knowledge of tick-borne disease ecology in east Texas which can aid in directing future investigative, modeling, and management efforts.

RevDate: 2020-01-08

Basting PJ, CM Bergman (2019)

Complete Genome Assemblies for Three Variants of the Wolbachia Endosymbiont of Drosophila melanogaster.

Microbiology resource announcements, 8(45):.

Here, we report genome assemblies for three strains of Wolbachia pipientis, assembled from unenriched, unfiltered long-read shotgun sequencing data of geographically distinct strains of Drosophila melanogaster Our simple methodology can be applied to long-read data sets of other Wolbachia-infected species with limited Wolbachia-host lateral gene transfers to produce complete assemblies for this important model symbiont.

RevDate: 2020-01-08

Yuen B, Polzin J, JM Petersen (2019)

Organ transcriptomes of the lucinid clam Loripes orbiculatus (Poli, 1791) provide insights into their specialised roles in the biology of a chemosymbiotic bivalve.

BMC genomics, 20(1):820.

BACKGROUND: The lucinid clam Loripes orbiculatus lives in a nutritional symbiosis with sulphur-oxidizing bacteria housed in its gills. Although our understanding of the lucinid endosymbiont physiology and metabolism has made significant progress, relatively little is known about how the host regulates the symbiosis at the genetic and molecular levels. We generated transcriptomes from four L. orbiculatus organs (gills, foot, visceral mass, and mantle) for differential expression analyses, to better understand this clam's physiological adaptations to a chemosymbiotic lifestyle, and how it regulates nutritional and immune interactions with its symbionts.

RESULTS: The transcriptome profile of the symbiont-housing gill suggests the regulation of apoptosis and innate immunity are important processes in this organ. We also identified many transcripts encoding ion transporters from the solute carrier family that possibly allow metabolite exchange between host and symbiont. Despite the clam holobiont's clear reliance on chemosynthesis, the clam's visceral mass, which contains the digestive tract, is characterised by enzymes involved in digestion, carbohydrate recognition and metabolism, suggesting that L. orbiculatus has a mixotrophic diet. The foot transcriptome is dominated by the biosynthesis of glycoproteins for the construction of mucus tubes, and receptors that mediate the detection of chemical cues in the environment.

CONCLUSIONS: The transcriptome profiles of gills, mantle, foot and visceral mass provide insights into the molecular basis underlying the functional specialisation of bivalve organs adapted to a chemosymbiotic lifestyle.

RevDate: 2020-01-13

Karut K, Castle SJ, Karut ŞT, et al (2019)

Secondary endosymbiont diversity of Bemisia tabaci and its parasitoids.

Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases, 78:104104 pii:S1567-1348(19)30330-2 [Epub ahead of print].

Cotton whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is one of the most important insect pests worldwide. It is known as a species complex consisting of at least 40 cryptic species. Although there are substantial data regarding species composition, parasitoids and endosymbionts of B. tabaci, data on relationship between the pest, parasitoids and endosymbionts are very restricted. Therefore, in this study, secondary endosymbionts in populations of B. tabaci and their parasitoids collected from Turkey and the USA were determined by PCR-based DNA analysis. Whitefly populations in Turkey represented both Mediterranean (MED) and Middle East-Asia Minor1 (MEAM1) genotypes from single or mixed populations of both genotypes. Arsenophonus, Rickettsia and Wolbachia were found in MED, while Hamiltonella and Rickettsia in MEAM1. Whitefly populations collected from Arizona were all MEAM1 and dually infected with Hamiltonella and Rickettsia. The aphelinid parasitoids Encarsia lutea and Eretmocerus mundus predominated in all Turkish populations. While almost all En. lutea populations were infected with Wolbachia, no endosymbionts were detected in any Er. mundus. Parasitoid species and the pattern of secondary endosymbiont infection in Arizona populations were different with Rickettsia detected only from Encarsia sophia while both Rickettsia and Wolbachia were found in Eretmocerus species. As a result, four secondary endosymbionts, namely, Rickettsia, Hamiltonella, Arsenophonus and Wolbachia, were detected from B.tabaci and its parasitoids. Among them only Wolbachia and Rickettsia were found in both the pest and parasitoids. It is conclude that further studies should be pursued to determine effect of these endosymbionts on biology of the parasitoids and success in biological control of B. tabaci.

RevDate: 2019-12-17

Bellantuono AJ, Dougan KE, Granados-Cifuentes C, et al (2019)

Free-living and symbiotic lifestyles of a thermotolerant coral endosymbiont display profoundly distinct transcriptomes under both stable and heat stress conditions.

Molecular ecology, 28(24):5265-5281.

Reef-building corals depend upon a nutritional endosymbiosis with photosynthetic dinoflagellates of the family Symbiodiniaceae for the majority of their energetic needs. While this mutualistic relationship is impacted by numerous stressors, warming oceans are a predominant threat to coral reefs, placing the future of the world's reefs in peril. Some Symbiodiniaceae species exhibit tolerance to thermal stress, but the in hospite symbiont response to thermal stress is underexplored. To describe the underpinnings of symbiosis and heat stress response, we compared in hospite and free-living transcriptomes of Durusdinium trenchii, a pan-tropical heat-tolerant Symbiodiniaceae species, under stable temperature conditions and acute hyperthermal stress. We discovered that symbiotic state was a larger driver of the transcriptional landscape than heat stress. The majority of differentially expressed transcripts between in hospite and free-living cells were downregulated, suggesting the in hospite condition is associated with the shutdown of numerous processes uniquely required for a free-living lifestyle. In the free-living state, we identified enrichment for numerous cell signalling pathways and other functions related to detecting and responding to a changing environment, as well as transcripts relating to mitosis, meiosis, and motility. In contrast, in hospite cells exhibited enhanced transcriptional activity for photosynthesis and carbohydrate transport as well as chromatin modifications and a disrupted circadian clock. Hyperthermal stress induced drastic alteration of transcriptional activity in hospite, suggesting symbiotic engagement with the host elicited an exacerbated stress response when compared to free-living D. trenchii. Altogether, the dramatic differences in gene expression between in hospite and free-living D. trenchii indicate the importance of considering symbiotic state in investigations of symbiosis and hyperthermal stress in Symbiodiniaceae.

RevDate: 2019-12-17
CmpDate: 2019-12-16

Durden L, Wang D, Panaccione D, et al (2019)

Decreased Root-Knot Nematode Gall Formation in Roots of the Morning Glory Ipomoea tricolor Symbiotic with Ergot Alkaloid-Producing Fungal Periglandula Sp.

Journal of chemical ecology, 45(10):879-887.

Many species of morning glories (Convolvulaceae) form symbioses with seed-transmitted Periglandula fungal endosymbionts, which produce ergot alkaloids and may contribute to defensive mutualism. Allocation of seed-borne ergot alkaloids to various tissues of several Ipomoea species has been demonstrated, including roots of I. tricolor. The goal of this study was to determine if infection of I. tricolor by the Periglandula sp. endosymbiont affects Southern root-knot nematode (Meloidogyne incognita) gall formation and host plant biomass. We hypothesized that I. tricolor plants infected by Periglandula (E+) would develop fewer nematode-induced galls compared to non-symbiotic plants (E-). E+ or E- status of plant lines was confirmed by testing methanol extracts from individual seeds for endosymbiont-produced ergot alkaloids. To test the effects of Periglandula on nematode colonization, E+ and E- I. tricolor seedlings were grown in soil infested with high densities of M. incognita nematodes (N+) or no nematodes (N-) for four weeks in the greenhouse before harvesting. After harvest, nematode colonization of roots was visualized microscopically, and total gall number and plant biomass were quantified. Four ergot alkaloids were detected in roots of E+ plants, but no alkaloids were found in E- plants. Gall formation was reduced by 50% in E+ plants compared to E- plants, independent of root biomass. Both N+ plants and E+ plants had significantly reduced biomass compared to N- and E- plants, respectively. These results demonstrate Periglandula's defensive role against biotic enemies, albeit with a potential trade-off with host plant growth.

RevDate: 2019-12-23

Murik O, Chandran SA, Nevo-Dinur K, et al (2019)

Topologies of N6 -adenosine methylation (m6 A) in land plant mitochondria and their putative effects on organellar gene expression.

The Plant journal : for cell and molecular biology [Epub ahead of print].

Mitochondria serve as major sites of ATP production and play key roles in many other metabolic processes that are critical to the cell. As relicts of an ancient bacterial endosymbiont, mitochondria contain their own hereditary material (i.e. mtDNA, or mitogenome) and a machinery for protein biosynthesis. The expression of the mtDNA in plants is complex, particularly at the post-transcriptional level. Following transcription, the polycistronic pre-RNAs undergo extensive modifications, including trimming, splicing and editing, before being translated by organellar ribosomes. Our study focuses on N6 -methylation of adenosine ribonucleotides (m6 A-RNA) in plant mitochondria. m6 A is a prevalent modification in nuclear-encoded mRNAs. The biological significance of this dynamic modification is under investigation, but it is widely accepted that m6 A mediates structural switches that affect RNA stability and/or activity. Using m6 A-pulldown/RNA-seq (m6 A-RIP-seq) assays of Arabidopsis and cauliflower mitochondria, we provide information on the m6 A-RNA landscapes in Arabidopsis thaliana and Brassica oleracea mitochondria. The results show that m6 A targets different types of mitochondrial transcripts, including known genes, mtORFs, as well as non-coding (transcribed intergenic) RNA species. While ncRNAs undergo multiple m6 A modifications, N6 -methylation of adenosine residues with mRNAs seem preferably positioned near start codons and may modulate their translatability.

RevDate: 2019-10-28

Chigurupati S, Vijayabalan S, Selvarajan KK, et al (2019)

Antimicrobial Exploration Between Counterpart Endosymbiont and Host Plant (Tamarindus indica Linn.).

Current pharmaceutical biotechnology pii:CPB-EPUB-101945 [Epub ahead of print].

BACKGROUND: Endophytes, notably receiving attention, have been observed to be potential sources of bioactive metabolites.

OBJECTIVES: In the present study, endophyte was isolated from the leaves of Tamarindus indica and screened for antimicrobial potential.

METHODS: The selected endophyte was identified by 16s rRNA partial genome sequencing and investigated for their antimicrobial potency. The preliminary phytochemical test was conducted for the affirmation of phytoconstituents in the endophytic crude ethyl acetate extract of T. indica (TIM). The antimicrobial potential of TIM was evaluated against human pathogenic ATCC strains.

RESULTS: TIM exhibited the Minimum Inhibitory Concentration (MIC) at 250 μg/mL and Minimum Bactericidal Concentration at 500 μg/mL among the selected human pathogenic ATCC strains of gram positive and gram negative bacteria. At MIC of 500 μg/mL, TIM displayed significant zone of inhibition against P. aeruginosa and N. gonorrhoeae.

CONCLUSION: TIM was proved to be a phytoremedy with potential antimicrobial property.

RevDate: 2020-01-08

Gasser MT, Chung M, Bromley RE, et al (2019)

Complete Genome Sequence of wAna, the Wolbachia Endosymbiont of Drosophila ananassae.

Microbiology resource announcements, 8(43):.

Here, we present the complete genome sequence of the Wolbachia endosymbiont wAna, isolated from Drosophila ananassae and derived from Oxford Nanopore and Illumina sequencing. We anticipate that this will aid in Wolbachia comparative genomics and the assembly of D. ananassae specifically in regions containing extensive lateral gene transfer events.

RevDate: 2020-01-08

Chicana B, Couper LI, Kwan JY, et al (2019)

Comparative Microbiome Profiles of Sympatric Tick Species from the Far-Western United States.

Insects, 10(10):.

Insight into the composition and function of the tick microbiome has expanded considerably in recent years. Thus far, tick microbiome studies have focused on species and life stages that are responsible for transmitting disease. In this study we conducted extensive field sampling of six tick species in the far-western United States to comparatively examine the microbial composition of sympatric tick species: Ixodes pacificus, Ixodesangustus, Dermacentor variabilis, Dermacentor occidentalis, Dermacentor albipictus, and Haemaphysalis leporispalustris. These species represent both common vectors of disease and species that rarely encounter humans, exhibiting a range of host preferences and natural history. We found significant differences in microbial species diversity and composition by tick species and life stage. The microbiome of most species examined were dominated by a few primary endosymbionts. Across all species, the relative abundance of these endosymbionts increased with life stage while species richness and diversity decreased with development. Only one species, I. angustus, did not show the presence of a single dominant microbial species indicating the unique physiology of this species or its interaction with the surrounding environment. Tick species that specialize in a small number of host species or habitat ranges exhibited lower microbiome diversity, suggesting that exposure to environmental conditions or host blood meal diversity can affect the tick microbiome which in turn may affect pathogen transmission. These findings reveal important associations between ticks and their microbial community and improve our understanding of the function of non-pathogenic microbiomes in tick physiology and pathogen transmission.

RevDate: 2019-12-21

Liu C, Cheng SH, S Lin (2020)

Illuminating the dark depths inside coral.

Cellular microbiology, 22(1):e13122.

The ability to observe in situ 3D distribution and dynamics of endosymbionts in corals is crucial for gaining a mechanistic understanding of coral bleaching and reef degradation. Here, we report the development of a tissue clearing (TC) coupled with light sheet fluorescence microscopy (LSFM) method for 3D imaging of the coral holobiont at single-cell resolution. The initial applications have demonstrated the ability of this technique to provide high spatial resolution quantitative information of endosymbiont abundance and distribution within corals. With specific fluorescent probes or assays, TC-LSFM also revealed spatial distribution and dynamics of physiological conditions (such as cell proliferation, apoptosis, and hypoxia response) in both corals and their endosymbionts. This tool is highly promising for in situ and in-depth data acquisition to illuminate coral symbiosis and health conditions in the changing marine environment, providing fundamental information for coral reef conservation and restoration.

RevDate: 2020-01-08

Bi J, YF Wang (2019)

The effect of the endosymbiont Wolbachia on the behavior of insect hosts.

Insect science [Epub ahead of print].

As one of the most successful intracellular symbiotic bacteria, Wolbachia can infect many arthropods and nematodes. Wolbachia infection usually affects the reproduction of their hosts to promote their own proliferation and transmission. Currently, most of the studies focus on the mechanisms of Wolbachia interactions with host reproduction. However, in addition to distribution in the reproductive tissues, Wolbachia also infect various somatic tissues of their hosts, including the brain. This raises the potential that Wolbachia may influence some somatic processes, such as behaviors in their hosts. So far, information about the effects of Wolbachia infection on host behavior is still very limited. The present review presents the current literature on different aspects of the influence of Wolbachia on various behaviors, including sleep, learning and memory, mating, feeding and aggression in their insect hosts. We then highlight ongoing scientific efforts in the field that need addressing to advance this field, which can have significant implications for further developing Wolbachia as environmentally friendly biocontrol agents to control insect-borne diseases and agricultural pests.

RevDate: 2020-01-08

Radkov AD, S Chou (2019)

An Affair to Remember: How an Endosymbiont Partners with Its Host to Build a Cell Envelope.

Cell, 179(3):584-586.

Studying endosymbionts gives us insight into early cellular mechanisms that led to the emergence of eukaryotic organelles. In this issue of Cell, Bublitz et al. (2019) report on how a nested bacterial endosymbiont of mealybugs builds its cell wall peptidoglycan through a biosynthetic pathway that is dependent on transported host enzymes.

RevDate: 2020-01-16

Manzano-Marı N A, Coeur d'acier A, Clamens AL, et al (2020)

Serial horizontal transfer of vitamin-biosynthetic genes enables the establishment of new nutritional symbionts in aphids' di-symbiotic systems.

The ISME journal, 14(1):259-273.

Many insects depend on obligate mutualistic bacteria to provide essential nutrients lacking from their diet. Most aphids, whose diet consists of phloem, rely on the bacterial endosymbiont Buchnera aphidicola to supply essential amino acids and B vitamins. However, in some aphid species, provision of these nutrients is partitioned between Buchnera and a younger bacterial partner, whose identity varies across aphid lineages. Little is known about the origin and the evolutionary stability of these di-symbiotic systems. It is also unclear whether the novel symbionts merely compensate for losses in Buchnera or carry new nutritional functions. Using whole-genome endosymbiont sequences of nine Cinara aphids that harbour an Erwinia-related symbiont to complement Buchnera, we show that the Erwinia association arose from a single event of symbiont lifestyle shift, from a free-living to an obligate intracellular one. This event resulted in drastic genome reduction, long-term genome stasis, and co-divergence with aphids. Fluorescence in situ hybridisation reveals that Erwinia inhabits its own bacteriocytes near Buchnera's. Altogether these results depict a scenario for the establishment of Erwinia as an obligate symbiont that mirrors Buchnera's. Additionally, we found that the Erwinia vitamin-biosynthetic genes not only compensate for Buchnera's deficiencies, but also provide a new nutritional function; whose genes have been horizontally acquired from a Sodalis-related bacterium. A subset of these genes have been subsequently transferred to a new Hamiltonella co-obligate symbiont in one specific Cinara lineage. These results show that the establishment and dynamics of multi-partner endosymbioses can be mediated by lateral gene transfers between co-ocurring symbionts.

RevDate: 2020-01-16

Galis F, JJM van Alphen (2020)

Parthenogenesis and developmental constraints.

Evolution & development, 22(1-2):205-217.

The absence of a paternal contribution in an unfertilized ovum presents two developmental constraints against the evolution of parthenogenesis. We discuss the constraint caused by the absence of a centrosome and the one caused by the missing set of chromosomes and how they have been broken in specific taxa. They are examples of only a few well-underpinned examples of developmental constraints acting at macro-evolutionary scales in animals. Breaking of the constraint of the missing chromosomes is the best understood and generally involves rare occasions of drastic changes of meiosis. These drastic changes can be best explained by having been induced, or at least facilitated, by sudden cytological events (e.g., repeated rounds of hybridization, endosymbiont infections, and contagious infections). Once the genetic and developmental machinery is in place for regular or obligate parthenogenesis, shifts to other types of parthenogenesis can apparently rather easily evolve, for example, from facultative to obligate parthenogenesis, or from pseudoarrhenotoky to haplodiploidy. We argue that the combination of the two developmental constraints forms a near-absolute barrier against the gradual evolution from sporadic to obligate or regular facultative parthenogenesis, which can probably explain why the occurrence of the highly advantageous mode of regular facultative parthenogenesis is so rare and entirely absent in vertebrates.

RevDate: 2019-11-19

Aoyagi S, Kodama Y, Passarelli MK, et al (2019)

OrbiSIMS Imaging Identifies Molecular Constituents of the Perialgal Vacuole Membrane of Paramecium bursaria with Symbiotic Chlorella variabilis.

Analytical chemistry, 91(22):14545-14551.

The protist (mostly single-celled organisms), Paramecium bursaria, forms an intracellular symbiotic relationship with the single-celled algae, Chlorella variabilis, where P. bursaria provides nutrients (i.e., Ca2+, Mg2+, and K+), carbon dioxide for photosynthesis and protection from viruses, while C. variabilis provides oxygen, carbon fixation, and nutrients. Key to this successful relationship is the perialgal vacuole (PV) membrane, which surrounds C. variabilis and protects it from digestion by P. bursaria. The membrane is fragile and difficult to analyze using conventional methods therefore very little is known about the molecular composition. We used the OrbiSIMS, a new high-resolution mass spectrometer with subcellular resolution imaging, to study the compartmentalization of endosymbionts and elucidate biomolecular interactions between the host and endosymbiont. Ions from the region of interest, close to C. variabilis, and specific to the target samples containing PVs were found based on the chemical mapping and masses of the ions. We show chemical localizations of oligosaccharides in close proximity of C. variabilis endosymbionts in P. bursaria. These oligosaccharides are detected in host-endosymbiont samples containing PV membrane-bound algae and absent in free-living algae and digestive vacuole (DV) membrane-bound algae in P. bursaria.

RevDate: 2020-01-08

Liang Z, Liu F, Wang W, et al (2019)

High-throughput sequencing revealed differences of microbial community structure and diversity between healthy and diseased Caulerpa lentillifera.

BMC microbiology, 19(1):225.

BACKGROUND: Caulerpa lentillifera is one of the most important economic green macroalgae in the world. Increasing demand for consumption has led to the commercial cultivation of C. lentillifera in Japan and Vietnam in recent decades. Concomitant with the increase of C. lentillifera cultivation is a rise in disease. We hypothesise that epiphytes or other microorganisms outbreak at the C. lentillifera farm may be an important factor contributing to disease in C. lentillifera. The main aims are obtaining differences in the microbial community structure and diversity between healthy and diseased C. lentillifera and key epiphytes and other microorganisms affecting the differences through the results of high-throughput sequencing and bioinformatics analysis in the present study.

RESULTS: A total of 14,050, 2479, and 941 operational taxonomic units (OTUs) were obtained from all samples using 16S rDNA, 18S rDNA, and internal transcribed spacer (ITS) high-throughput sequencing, respectively. 16S rDNA sequencing and 18S rDNA sequencing showed that microbial community diversity was higher in diseased C. lentillifera than in healthy C. lentillifera. Both PCoA results and UPGMA results indicated that the healthy and diseased algae samples have characteristically different microbial communities. The predominant prokaryotic phyla were Proteobacteria, Planctomycetes, Bacteroidetes, Cyanobacteria, Acidobacteria, Acidobacteria and Parcubacteria in all sequences. Chlorophyta was the most abundant eukaryotic phylum followed by Bacillariophyta based on 18S rDNA sequencing. Ascomycota was the dominant fungal phylum detected in healthy C. lentillifera based on ITS sequencing, whereas fungi was rare in diseased C. lentillifera, suggesting that Ascomycota was probably fungal endosymbiont in healthy C. lentillifera. There was a significantly higher abundance of Bacteroidetes, Cyanobacteria, Bacillariophyta, Ulvales and Tetraselmis in diseased C. lentillifera than in healthy C. lentillifera. Disease outbreaks significantly change carbohydrate metabolism, environmental information processing and genetic information processing of prokaryotic communities in C. lentillifera through predicted functional analyses using the Tax4Fun tool.

CONCLUSIONS: Bacteroidetes, Cyanobacteria, Bacillariophyta, Ulvales and Tetraselmis outbreak at the C. lentillifera farm sites was an important factor contributing to disease in C. lentillifera.

RevDate: 2019-10-23

Chiodi A, Comandatore F, Sassera D, et al (2019)

SeqDeχ: A Sequence Deconvolution Tool for Genome Separation of Endosymbionts From Mixed Sequencing Samples.

Frontiers in genetics, 10:853.

In recent years, the advent of NGS technology has made genome sequencing much cheaper than in the past; the high parallelization capability and the possibility to sequence more than one organism at once have opened the door to processing whole symbiotic consortia. However, this approach needs the development of specific bioinformatics tools able to analyze these data. In this work, we describe SeqDex, a tool that starts from a preliminary assembly obtained from sequencing a mixture of DNA from different organisms, to identify the contigs coming from one organism of interest. SeqDex is a fully automated machine learning-based tool exploiting partial taxonomic affiliations and compositional analysis to predict the taxonomic affiliations of contigs in an assembly. In literature, there are few methods able to deconvolve host-symbiont datasets, and most of them heavily rely on user curation and are therefore time consuming. The problem has strong similarities with metagenomic studies, where mixed samples are sequenced and the bioinformatics challenge is trying to separate contigs on the basis of their source organism; however, in symbiotic systems, additional information can be exploited to improve the output. To assess the ability of SeqDex to deconvolve host-symbiont datasets, we compared it to state-of-the-art methods for metagenomic binning and for host-symbiont deconvolution on three study cases. The results point out the good performances of the presented tool that, in addition to the ease of use and customization potential, make SeqDex a useful tool for rapid identification of endosymbiont sequences.

RevDate: 2019-10-23

Gifford I, Vance S, Nguyen G, et al (2019)

A Stable Genetic Transformation System and Implications of the Type IV Restriction System in the Nitrogen-Fixing Plant Endosymbiont Frankia alni ACN14a.

Frontiers in microbiology, 10:2230.

Genus Frankia is comprised primarily of nitrogen-fixing actinobacteria that form root nodule symbioses with a group of hosts known as the actinorhizal plants. These plants are evolutionarily closely related to the legumes that are nodulated by the rhizobia. Both host groups utilize homologs of nodulation genes for root-nodule symbiosis, derived from common plant ancestors. The corresponding endosymbionts, Frankia and the rhizobia, however, are distantly related groups of bacteria, leading to questions about their symbiotic mechanisms and evolutionary history. To date, a stable system of electrotransformation has been lacking in Frankia despite numerous attempts by research groups worldwide. We have identified type IV methyl-directed restriction systems, highly-expressed in a range of actinobacteria, as a likely barrier to Frankia transformation. Here we report the successful electrotransformation of the model strain F. alni ACN14a with an unmethylated, broad host-range replicating plasmid, expressing chloramphenicol-resistance for selection and GFP as a marker of gene expression. This system circumvented the type IV restriction barrier and allowed the stable maintenance of the plasmid. During nitrogen limitation, Frankia differentiates into two cell types: the vegetative hyphae and nitrogen-fixing vesicles. When the expression of egfp under the control of the nif gene cluster promoter was localized using fluorescence imaging, the expression of nitrogen fixation in nitrogen-limited culture was localized in Frankia vesicles but not in hyphae. The ability to separate gene expression patterns between Frankia hyphae and vesicles will enable deeper comparisons of molecular signaling and metabolic exchange between Frankia-actinorhizal and rhizobia-legume symbioses to be made, and may broaden potential applications in agriculture. Further downstream applications are possible, including gene knock-outs and complementation, to open up a range of experiments in Frankia and its symbioses. Additionally, in the transcriptome of F. alni ACN14a, type IV restriction enzymes were highly expressed in nitrogen-replete culture but their expression strongly decreased during symbiosis. The down-regulation of type IV restriction enzymes in symbiosis suggests that horizontal gene transfer may occur more frequently inside the nodule, with possible new implications for the evolution of Frankia.

RevDate: 2020-01-08

Caputo B, Moretti R, Manica M, et al (2019)

A bacterium against the tiger: preliminary evidence of fertility reduction after release of Aedes albopictus males with manipulated Wolbachia infection in an Italian urban area.

Pest management science [Epub ahead of print].

BACKGROUND: Novel tools are needed to reduce the nuisance and risk of exotic arbovirus transmission associated with the colonization of temperate regions by Aedes albopictus. The incompatible insect technique (IIT) is a population suppression approach based on cytoplasmic incompatibility between males with manipulated endosymbionts and wild females. Here, we present the results of the first field experiment in Europe to assess the capacity of an Ae. albopictus line (ARwP) deprived of its natural endosymbiont Wolbachia and transinfected with a Wolbachia strain from the mosquito Culex pipiens, to sterilize wild females.

RESULTS: We released ∼ 4500 ARwP males weekly for 6 weeks in a green area within urban Rome (Italy) and carried out egg (N = 13 442), female (N = 128) and male (N = 352) collections. Egg (N = 13 783) and female (N = 48) collections were also carried out at two untreated control sites. The percentage of viable eggs during release was, on average, significantly lower in treated sites than in control sites, with the greatest difference (16%) seen after the fourth release. The ARwP to wild male ratio in the release spots between day 3 after the first ARwP male release and day 7 after the last release was, on average, 7:10. Released males survived up to 2 weeks. Approximately 30% of females collected in the release spots showed 100% sterility and 20% showed strongly reduced fertility compared with control sites.

CONCLUSIONS: Results support the potential of IIT as a tool contributing to Ae. albopictus control in the urban context, and stress the need for larger field trials to evaluate the cost-efficacy of the approach in suppressing wild populations. © 2019 Society of Chemical Industry.

RevDate: 2020-01-08

Obert T, P Vďačný (2019)

Evolutionary Origin and Host Range of Plagiotoma lumbrici (Ciliophora, Hypotrichia), an Obligate Gut Symbiont of Lumbricid Earthworms.

The Journal of eukaryotic microbiology [Epub ahead of print].

Four common earthworm species, the anecic Lumbricus terrestris, the endogeic Octolasion tyrteum as well as the epigeic Eisenia fetida and Dendrobaena veneta, were examined for the presence of the microbial gut symbiont Plagiotoma lumbrici. The evolutionary origin of this endobiotic microbe was reconstructed, using the 18S rRNA gene, the ITS1-5.8S-ITS2 region, and the first two domains of the 28S rRNA gene. Plagiotoma lumbrici was exclusively detected in the anecic Lumbricus terrestris. Multigene analyses and the ITS2 secondary structure robustly determined the phylogenetic home of Plagiotoma lumbrici populations within the oxytrichid Dorsomarginalia (Spirotrichea: Hypotrichia) as a sister taxon of the free-living Hemiurosomoida longa. This indicates that earthworms obtained their gut endosymbiont by ingesting soil/leaf litter containing oxytrichine ciliates that became adapted to the intestinal tract of earthworms. Interestingly, according to the literature data, Plagiotoma lumbrici was detected in multiple anecic and some epigeic but never in endogeic earthworms. These observations suggest that Plagiotoma lumbrici might be adapted to certain gut conditions and the lifestyle of anecic Lumbricidae, such as Lumbricus, Aporrectodea, and Scherotheca, as well as of some co-occurring epigeic Lumbricus species.

RevDate: 2020-01-08

Bondarenko N, Volkova E, Masharsky A, et al (2019)

A Comparative Characterization of the Mitochondrial Genomes of Paramoeba aparasomata and Neoparamoeba pemaquidensis (Amoebozoa, Paramoebidae).

The Journal of eukaryotic microbiology [Epub ahead of print].

Marine amebae of the genus Paramoeba (Amoebozoa, Dactylopodida) normally contain a eukaryotic endosymbiont known as Perkinsela-like organism (PLO). This is one of the characters to distinguish the genera Neoparamoeba and Paramoeba from other Dactylopodida. It is known that the PLO may be lost, but PLO-free strains of paramoebians were never available for molecular studies. Recently, we have described the first species of the genus Paramoeba which has no parasome-Paramoeba aparasomata. In this study, we present a mitochondrial genome of this species, compare it with that of Neoparamoeba pemaquidensis, and analyze the evolutionary dynamics of gene sequences and gene order rearrangements between these species. The mitochondrial genome of P. aparasomata is 46,254 bp long and contains a set of 31 protein-coding genes, 19 tRNAs, two rRNA genes, and 7 open reading frames. Our results suggest that these two mitochondrial genomes within the genus Paramoeba have rather similar organization and gene order, base composition, codon usage, the composition and structure of noncoding, and overlapping regions.

RevDate: 2020-01-08

Bing XL, Lu YJ, Xia CB, et al (2019)

Transcriptome of Tetranychus urticae embryos reveals insights into Wolbachia-induced cytoplasmic incompatibility.

Insect molecular biology [Epub ahead of print].

The endosymbiont Wolbachia is known for manipulating host reproduction in selfish ways. However, the molecular mechanisms have not yet been investigated in embryos. Here, we found that Wolbachia had no effect on the number of deposited eggs in Tetranychus urticae Koch (Acari: Tetranychidae) but caused two types of reproductive manipulation: killing uninfected female embryos via cytoplasmic incompatibility (CI) and increasing the hatching ratio of infected female embryos. RNA sequencing analyses showed that 145 genes were differentially expressed between Wolbachia-infected (WI) and Wolbachia-uninfected (WU) embryos. Wolbachia infection down-regulated messenger RNA (mRNA) expression of glutathione S-transferase that could buffer oxidative stress. In addition, 1613 and 294 genes were identified as CI-specific up-/down-regulated genes. Compared to WU and WI embryos, embryos of CI cross strongly expressed genes involved in transcription, translation, tissue morphogenesis, DNA damage and mRNA surveillance. In contrast, most of the genes associated with energy production and metabolism were down-regulated in the CI embryos compared to the WU and WI embryos, which provides some clues as to the cause of death of CI embryos. These results identify several genes that could be candidates for explaining Wolbachia-induced CI. Our data form a basis to help elucidate the molecular consequences of CI in embryos.

RevDate: 2019-11-14

Bublitz DC, Chadwick GL, Magyar JS, et al (2019)

Peptidoglycan Production by an Insect-Bacterial Mosaic.

Cell, 179(3):703-712.e7.

Peptidoglycan (PG) is a defining feature of bacteria, involved in cell division, shape, and integrity. We previously reported that several genes related to PG biosynthesis were horizontally transferred from bacteria to the nuclear genome of mealybugs. Mealybugs are notable for containing a nested bacteria-within-bacterium endosymbiotic structure in specialized insect cells, where one bacterium, Moranella, lives in the cytoplasm of another bacterium, Tremblaya. Here we show that horizontally transferred genes on the mealybug genome work together with genes retained on the Moranella genome to produce a PG layer exclusively at the Moranella cell periphery. Furthermore, we show that an insect protein encoded by a horizontally transferred gene of bacterial origin is transported into the Moranella cytoplasm. These results provide a striking parallel to the genetic and biochemical mosaicism found in organelles, and prove that multiple horizontally transferred genes can become integrated into a functional pathway distributed between animal and bacterial endosymbiont genomes.

RevDate: 2019-10-23

Tyml T, Date SV, T Woyke (2019)

A single-cell genome perspective on studying intracellular associations in unicellular eukaryotes.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 374(1786):20190082.

Single-cell genomics (SCG) methods provide a unique opportunity to analyse whole genome information at the resolution of an individual cell. While SCG has been extensively used to investigate bacterial and archaeal genomes, the technique has been rarely used to access the genetic makeup of uncultivated microbial eukaryotes. In this regard, the use of SCG can provide a wealth of information; not only do the methods allow exploration of the genome, they can also help elucidate the relationship between the cell and intracellular entities extant in nearly all eukaryotes. SCG enables the study of total eukaryotic cellular DNA, which in turn allows us to better understand the evolutionary history and diversity of life, and the physiological interactions that define complex organisms. This article is part of a discussion meeting issue 'Single cell ecology'.

RevDate: 2019-12-18

Takeshita K, Yamada T, Kawahara Y, et al (2019)

Tripartite Symbiosis of an Anaerobic Scuticociliate with Two Hydrogenosome-Associated Endosymbionts, a Holospora-Related Alphaproteobacterium and a Methanogenic Archaeon.

Applied and environmental microbiology, 85(24):.

A number of anaerobic ciliates, unicellular eukaryotes, intracellularly possess methanogenic archaea and bacteria as symbiotic partners. Although this tripartite relationship is of interest in terms of the fact that each participant is from a different domain, the difficulty in culture and maintenance of those host species with symbiotic partners has disturbed both ecological and functional studies so far. In this study, we obtained a stable culture of a small anaerobic scuticociliate, strain GW7. By transmission electron microscopic observation and fluorescent in situ hybridization with domain-specific probes, we demonstrate that GW7 possesses both archaeal and bacterial endosymbionts in its cytoplasm. These endosymbionts are in dependently associated with hydrogenosomes, which are organelle producing hydrogen and ATP under anaerobic conditions. Clone library analyses targeting prokaryotic 16S rRNA genes, fluorescent in situ hybridization with endosymbiont-specific probes, and molecular phylogenetic analyses revealed the phylogenetic affiliations and intracellular localizations of these endosymbionts. The endosymbiotic archaeon is a methanogen belonging to the genus Methanoregula (order Methanomicrobiales); a member of this genus has previously been described as the endosymbiont of an anaerobic ciliate from the genus Metopus (class Armophorea), which is only distantly related to strain GW7 (class Oligohymenophorea). The endosymbiotic bacterium belongs to the family Holosporaceae of the class Alphaproteobacteria, which also comprises several endosymbionts of various aerobic ciliates. For this endosymbiotic bacterium, we propose a novel candidate genus and species, "Candidatus Hydrogenosomobacter endosymbioticus."IMPORTANCE Tripartite symbioses between anaerobic ciliated protists and their intracellular archaeal and bacterial symbionts are not uncommon, but most reports have been based mainly on microscopic observations. Deeper insights into the function, ecology, and evolution of these fascinating symbioses involving partners from all three domains of life have been hampered by the difficulties of culturing anaerobic ciliates in the laboratory and the frequent loss of their prokaryotic partners during long-term cultivation. In the present study, we report the isolation of an anaerobic scuticociliate, strain GW7, which has been stably maintained in our laboratory for more than 3 years without losing either of its endosymbionts. Unexpectedly, molecular characterization of the endosymbionts revealed that the bacterial partner of GW7 is phylogenetically related to intranuclear endosymbionts of aerobic ciliates. This strain will enable future genomic, transcriptomic, and proteomic analyses of the interactions in this tripartite symbiosis and a comparison with endosymbioses in aerobic ciliates.

RevDate: 2019-11-28

Spicer GLC, Eid A, Wangpraseurt D, et al (2019)

Measuring light scattering and absorption in corals with Inverse Spectroscopic Optical Coherence Tomography (ISOCT): a new tool for non-invasive monitoring.

Scientific reports, 9(1):14148.

The success of reef-building corals for >200 million years has been dependent on the mutualistic interaction between the coral host and its photosynthetic endosymbiont dinoflagellates (family Symbiodiniaceae) that supply the coral host with nutrients and energy for growth and calcification. While multiple light scattering in coral tissue and skeleton significantly enhance the light microenvironment for Symbiodiniaceae, the mechanisms of light propagation in tissue and skeleton remain largely unknown due to a lack of technologies to measure the intrinsic optical properties of both compartments in live corals. Here we introduce ISOCT (inverse spectroscopic optical coherence tomography), a non-invasive approach to measure optical properties and three-dimensional morphology of living corals at micron- and nano-length scales, respectively, which are involved in the control of light propagation. ISOCT enables measurements of optical properties in the visible range and thus allows for characterization of the density of light harvesting pigments in coral. We used ISOCT to characterize the optical scattering coefficient (μs) of the coral skeleton and chlorophyll a concentration of live coral tissue. ISOCT further characterized the overall micro- and nano-morphology of live tissue by measuring differences in the sub-micron spatial mass density distribution (D) that vary throughout the tissue and skeleton and give rise to light scattering, and this enabled estimates of the spatial directionality of light scattering, i.e., the anisotropy coefficient, g. Thus, ISOCT enables imaging of coral nanoscale structures and allows for quantifying light scattering and pigment absorption in live corals. ISOCT could thus be developed into an important tool for rapid, non-invasive monitoring of coral health, growth and photophysiology with unprecedented spatial resolution.

RevDate: 2020-01-10

Voronin D, Schnall E, Grote A, et al (2019)

Pyruvate produced by Brugia spp. via glycolysis is essential for maintaining the mutualistic association between the parasite and its endosymbiont, Wolbachia.

PLoS pathogens, 15(9):e1008085.

Human parasitic nematodes are the causative agents of lymphatic filariasis (elephantiasis) and onchocerciasis (river blindness), diseases that are endemic to more than 80 countries and that consistently rank in the top ten for the highest number of years lived with disability. These filarial nematodes have evolved an obligate mutualistic association with an intracellular bacterium, Wolbachia, a symbiont that is essential for the successful development, reproduction, and survival of adult filarial worms. Elimination of the bacteria causes adult worms to die, making Wolbachia a primary target for developing new interventional tools to combat filariases. To further explore Wolbachia as a promising indirect macrofilaricidal drug target, the essential cellular processes that define the symbiotic Wolbachia-host interactions need to be identified. Genomic analyses revealed that while filarial nematodes encode all the enzymes necessary for glycolysis, Wolbachia does not encode the genes for three glycolytic enzymes: hexokinase, 6-phosphofructokinase, and pyruvate kinase. These enzymes are necessary for converting glucose into pyruvate. Wolbachia, however, has the full complement of genes required for gluconeogenesis starting with pyruvate, and for energy metabolism via the tricarboxylic acid cycle. Therefore, we hypothesized that Wolbachia might depend on host glycolysis to maintain a mutualistic association with their parasitic host. We did conditional experiments in vitro that confirmed that glycolysis and its end-product, pyruvate, sustain this symbiotic relationship. Analysis of alternative sources of pyruvate within the worm indicated that the filarial lactate dehydrogenase could also regulate the local intracellular concentration of pyruvate in proximity to Wolbachia and thus help control bacterial growth via molecular interactions with the bacteria. Lastly, we have shown that the parasite's pyruvate kinase, the enzyme that performs the last step in glycolysis, could be a potential novel anti-filarial drug target. Establishing that glycolysis is an essential component of symbiosis in filarial worms could have a broader impact on research focused on other intracellular bacteria-host interactions where the role of glycolysis in supporting intracellular survival of bacteria has been reported.

RevDate: 2019-10-23

Gawande SJ, Anandhan S, Ingle A, et al (2019)

Microbiome profiling of the onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae).

PloS one, 14(9):e0223281.

The gut microbial community structure of adult Thrips tabaci collected from 10 different agro-climatically diverse locations of India was characterized by using the Illumina MiSeq platform to amplify the V3 region of the 16S rRNA gene of bacteria present in the sampled insects. Analyses were performed to study the bacterial communities associated with Thrips tabaci in India. The complete bacterial metagenome of T. tabaci was comprised of 1662 OTUs of which 62.25% belong to known and 37.7% of unidentified/unknown bacteria. These OTUs constituted 21 bacterial phyla of 276 identified genera. Phylum Proteobacteria was predominant, followed by Actinobacteria, Firmicutes, Bacteroidetes and Cyanobacteria. Additionally, the occurrence of the reproductive endosymbiont, Wolbachia was detected at two locations (0.56%) of the total known OTUs. There is high variation in diversity and species richness among the different locations. Alpha-diversity metrics indicated the higher gut bacterial diversity at Bangalore and lowest at Rahuri whereas higher bacterial species richness at T. tabaci samples from Imphal and lowest at Jhalawar. Beta diversity analyses comparing bacterial communities between the samples showed distinct differences in bacterial community composition of T. tabaci samples from different locations. This paper also constitutes the first record of detailed bacterial communities associated with T. tabaci. The location-wise variation in microbial metagenome profile of T. tabaci suggests that bacterial diversity might be governed by its population genetic structure, environment and habitat.

RevDate: 2020-01-08

Detcharoen M, Arthofer W, Schlick-Steiner BC, et al (2019)

Wolbachia megadiversity: 99% of these microorganismic manipulators unknown.

FEMS microbiology ecology, 95(11):.

Wolbachia (Alphaproteobacteria) are the most widespread endosymbionts of arthropods, manipulating their hosts by various means to maximize the number of host individuals infected. Based on quantitative analyzes of the published literature from Web of Science® and of DNA sequences of arthropod-hosted Wolbachia from GenBank, we made plausible that less than 1% of the expected 100 000 strains of Wolbachia in arthropods is known. Our findings suggest that more and globally better coordinated efforts in screening arthropods are needed to explore the true Wolbachia diversity and to help us understand the ecology and evolution of these host-endosymbiont interactions.

RevDate: 2019-10-23

Leveque S, Afiq-Rosli L, Ip YCA, et al (2019)

Searching for phylogenetic patterns of Symbiodiniaceae community structure among Indo-Pacific Merulinidae corals.

PeerJ, 7:e7669.

Over half of all extant stony corals (Cnidaria: Anthozoa: Scleractinia) harbour endosymbiotic dinoflagellates of the family Symbiodiniaceae, forming the foundational species of modern shallow reefs. However, whether these associations are conserved on the coral phylogeny remains unknown. Here we aim to characterise Symbiodiniaceae communities in eight closely-related species in the genera Merulina, Goniastrea and Scapophyllia, and determine if the variation in endosymbiont community structure can be explained by the phylogenetic relatedness among hosts. We perform DNA metabarcoding of the nuclear internal transcribed spacer 2 using Symbiodiniaceae-specific primers on 30 coral colonies to recover three major endosymbiont clades represented by 23 distinct types. In agreement with previous studies on Southeast Asian corals, we find an abundance of Cladocopium and Durusdinium, but also detect Symbiodinium types in three of the eight coral host species. Interestingly, differences in endosymbiont community structure are dominated by host variation at the intraspecific level, rather than interspecific, intergeneric or among-clade levels, indicating a lack of phylogenetic constraint in the coral-endosymbiont association among host species. Furthermore, the limited geographic sampling of four localities spanning the Western and Central Indo-Pacific preliminarily hints at large-scale spatial structuring of Symbiodiniaceae communities. More extensive collections of corals from various regions and environments will help us better understand the specificity of the coral-endosymbiont relationship.

RevDate: 2019-11-22

Molaei G, Little EAH, Stafford KC, et al (2020)

A seven-legged tick: Report of a morphological anomaly in Ixodes scapularis (Acari: Ixodidae) biting a human host from the Northeastern United States.

Ticks and tick-borne diseases, 11(1):101304.

Cases of morphological anomalies in the blacklegged tick, Ixodes scapularis (Acari: Ixodidae), have recently been reported from the Northeastern and upper Midwestern United States, potentially complicating identification of this important vector of human disease-causing pathogens. We hereby report a case of a morphological anomaly in I. scapularis, biting a human host residing in Norwich, Connecticut. Using a dichotomous morphological key, high-resolution and scanning electron microscopy images, as well as DNA sequencing, the tick was identified as an adult female I. scapularis with three legs on the left side of the abdomen versus four on the right side, which we believe is the first case of ectromely in an adult I. scapularis. Using diagnostic genes in polymerase chain reaction, the specimen tested positive for Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum, the causative agents for Lyme disease and anaplasmosis, respectively, and also showed evidence of a rickettsial endosymbiont. Here we discuss recent reports of morphological anomalies in I. scapularis, and emphasize the significance of additional studies of teratology in this important tick species and its potential implications.

RevDate: 2019-10-23

Feng H, Park JS, Zhai RG, et al (2019)

microRNA-92a regulates the expression of aphid bacteriocyte-specific secreted protein 1.

BMC research notes, 12(1):638.

OBJECTIVE: Aphids harbor a nutritional obligate endosymbiont in specialized cells called bacteriocytes, which aggregate to form an organ known as the bacteriome. Aphid bacteriomes display distinct gene expression profiles that facilitate the symbiotic relationship. Currently, the mechanisms that regulate these patterns of gene expression are unknown. Recently using computational pipelines, we identified miRNAs that are conserved in expression in the bacteriomes of two aphid species and proposed that they function as important regulators of bacteriocyte gene expression. Here using a dual luciferase assay in mouse NIH/3T3 cell culture, we aimed to experimentally validate the computationally predicted interaction between Myzus persicae miR-92a and the predicted target region of M. persicae bacteriocyte-specific secreted protein 1 (SP1) mRNA.

RESULTS: In the dual luciferase assay, miR-92a interacted with the SP1 target region resulting in a significant downregulation of the luciferase signal. Our results demonstrate that miR-92a interacts with SP1 to alter expression in a heterologous expression system, thereby supporting our earlier assertion that miRNAs are regulators of the aphid/Buchnera symbiotic interaction.

RevDate: 2020-01-17

Cato ML, Jester HD, Lavertu A, et al (2019)

Genome-Wide Analysis of Cell Cycle-Regulating Genes in the Symbiotic Dinoflagellate Breviolum minutum.

G3 (Bethesda, Md.), 9(11):3843-3853.

A delicate relationship exists between reef-building corals and their photosynthetic endosymbionts. Unfortunately, this relationship can be disrupted, with corals expelling these algae when temperatures rise even marginally above the average summer maximum. Interestingly, several studies indicate that failure of corals to regulate symbiont cell divisions at high temperatures may underlie this disruption; increased proliferation of symbionts may stress host cells by over-production of reactive oxygen species or by disrupting the flow of nutrients. This needs to be further investigated, so to begin deciphering the molecular mechanisms controlling the cell cycle in these organisms, we used a computational approach to identify putative cell cycle-regulating genes in the genome of the dinoflagellate Breviolum minutum This species is important as an endosymbiont of Aiptasia pallida-an anemone that is used as a model for studying coral biology. We then correlated expression of these putative cell cycle genes with cell cycle phase in diurnally growing B. minutum in culture. This approach allowed us to identify a cyclin/cyclin-dependent kinase pair that may function in the G1/S transition-a likely point for coral cells to exert control over algal cell divisions.

RevDate: 2020-01-08

Ogawa M, Takahashi M, Matsutani M, et al (2019)

Obligate intracellular bacteria diversity in unfed Leptotrombidium scutellare larvae highlights novel bacterial endosymbionts of mites.

Microbiology and immunology [Epub ahead of print].

It is well known that the mite Leptotrombidium scutellare carries the pathogen of scrub typhus, Orientia tsutsugamushi. However, our understanding of other bacterial endosymbionts of mites is limited. This study investigated the diversity of the obligate intracellular bacteria carried by L. scutellare using 16S rRNA gene amplicon analysis with next-generation sequencing. The results showed that the detected bacteria were classified into the genera Rickettsia, Wolbachia, and Rickettsiella and an unknown genus of the order Rickettsiales. For further classification of the detected bacteria, a representative read that was most closely related to the assigned taxonomic classification was subjected to homology search and phylogenic analysis. The results showed that some bacteria of the genus Rickettsia were identical or very close to the human pathogens Rickettsia akari, Rickettsia aeschlimannii, Rickettsia felis, and Rickettsia australis. The genetic distance between the genus Wolbachia bacteria in the present study and in previous reports is highly indicative that the bacteria in the present study can be classified as a new taxon of Wolbachia. This study detected obligate intracellular bacteria from unfed mites; thus, the mites did not acquire bacteria from infected animals or any other infectious sources. Finally, the present study demonstrated that various and novel bacterial endosymbionts of mites, in addition to O. tsutsugamushi, might uniquely evolve with the host mites throughout overlapping generations of the mite life cycle. The roles of the bacteria in mites and their pathogenicity should be further examined in studies based on bacterial isolation.

RevDate: 2019-11-26

Tian PP, Chang CY, Miao NH, et al (2019)

Infections with Arsenophonus Facultative Endosymbionts Alter Performance of Aphids (Aphis gossypii) on an Amino-Acid-Deficient Diet.

Applied and environmental microbiology, 85(23):.

Genetic polymorphism and endosymbiont infection are ubiquitous in aphid populations. It has been known that the obligate symbiont Buchnera provides aphids with essential amino acids which cannot be ingested from plant sap. Buchnera often coexists with facultative endosymbionts in aphids. However, it is unclear whether the facultative endosymbionts affect the aphid's amino acid requirements from diet. In this study, we found that the facultative endosymbiont status in populations of the cotton-melon aphid Aphis gossypii was associated with aphid genotype or host plant. The infection frequency of Arsenophonus in aphids living on cotton was significantly higher than that in aphids on cucumber, and cucumber leaves contained higher titers of free amino acids than cotton leaves, especially amino acids Leu, Arg, Ile, Val, and Phe. The net reproductive rates of five aphid genotypes infected with Arsenophonus were not different on the complete-amino-acid diet, but the values were significantly different among seven Arsenophonus-free aphid genotypes. Moreover, the net reproductive rates of aphids on the amino-acid-deficient diet were significantly affected by Arsenophonus infection and aphid genotype. Arsenophonus infection decreased aphid performance on the Phe-free diet but improved performance on the Leu-free diet and did not affect the performance on the Ile-free or Val-free diet. Arsenophonus infections altered aphid requirements for amino acids that were significantly different in cotton and cucumber leaves, suggesting this endosymbiont would modulate the host specialization of this aphid.IMPORTANCE The facultative endosymbiont Arsenophonus plays an important role in regulating reproduction through son killing, enemy resistance, and the dietary breadth of its insect hosts. In this study, we found Arsenophonus could alter aphid performance on the amino-acid-deficient diets. Arsenophonus infection increased aphid requirements for the amino acid Phe, but decreased requirements for the Leu. Cotton and cucumber leaves contained drastically different titers of free amino acids Phe and Leu, and aphids living on these two plants were infected with different incidences of Arsenophonus We hypothesize that host specialization or the host plant range of aphids may be mediated by Arsenophonus.

RevDate: 2019-10-08

Mead ME, Raja HA, Steenwyk JL, et al (2019)

Draft Genome Sequence of the Griseofulvin-Producing Fungus Xylaria flabelliformis Strain G536.

Microbiology resource announcements, 8(38): pii:8/38/e00890-19.

The draft genome of the ascomycete fungus Xylaria flabelliformis (previously known as Xylaria cubensis) was sequenced using Illumina paired-end technology. The assembled genome is 41.2 Mb long and contains 11,404 genes. This genome will contribute to our understanding of X. flabelliformis secondary metabolism and the organism's ability to live as a decomposer as well as an endosymbiont.

RevDate: 2019-09-12

Bellan A, Bucci F, Perin G, et al (2019)

Photosynthesis regulation in response to fluctuating light in the secondary endosymbiont alga Nannochloropsis gaditana.

Plant & cell physiology pii:5568101 [Epub ahead of print].

In nature, photosynthetic organisms are exposed to highly dynamic environmental conditions where the excitation energy and electron flow in the photosynthetic apparatus need to be continuously modulated. Fluctuations in incident light are particularly challenging since they drive oversaturation of photosynthesis, with consequent oxidative stress and photoinhibition. Plants and algae have evolved several mechanisms to modulate their photosynthetic machinery to cope with light dynamics, such as thermal dissipation of excited chlorophyll states (Non-Photochemical Quenching, NPQ) and regulation of electron transport. The regulatory mechanisms involved in the response to light dynamics have adapted during evolution and exploring biodiversity is a valuable strategy for expanding our understanding of their biological roles. In this work, we investigated the response to fluctuating light in Nannochloropsis gaditana, a eukaryotic microalga of the phylum Heterokonta originating from a secondary endosymbiotic event. N. gaditana is negatively affected by light fluctuations, leading to large reductions in growth and photosynthetic electron transport. Exposure to light fluctuations specifically damages photosystem I, likely because of ineffective regulation of electron transport in this species. The role of Non-Photochemical Quenching, also assessed using a mutant strain specifically depleted of this response, was instead found to be minor, especially in responding to the fastest light fluctuations.

RevDate: 2019-11-01

Smith DAS, Traut W, Martin SH, et al (2019)

Neo Sex Chromosomes, Colour Polymorphism and Male-Killing in the African Queen Butterfly, Danaus chrysippus (L.).

Insects, 10(9):.

Danaus chrysippus (L.), one of the world's commonest butterflies, has an extensive range throughout the Old-World tropics. In Africa it is divided into four geographical subspecies which overlap and hybridise freely in the East African Rift: Here alone a male-killing (MK) endosymbiont, Spiroplasma ixodetis, has invaded, causing female-biased populations to predominate. In ssp. chrysippus, inside the Rift only, an autosome carrying a colour locus has fused with the W chromosome to create a neo-W chromosome. A total of 40-100% of Rift females are neo-W and carry Spiroplasma, thus transmitting a linked, matrilineal neo-W, MK complex. As neo-W females have no sons, half the mother's genes are lost in each generation. Paradoxically, although neo-W females have no close male relatives and are thereby forced to outbreed, MK restricts gene flow between subspecies and may thus promote speciation. The neo-W chromosome originated in the Nairobi region around 2.2 k years ago and subsequently spread throughout the Rift contact zone in some 26 k generations, possibly assisted by not having any competing brothers. Our work on the neo-W chromosome, the spread of Spiroplasma and possible speciation is ongoing.

RevDate: 2020-01-10

Perlmutter JI, Bordenstein SR, Unckless RL, et al (2019)

The phage gene wmk is a candidate for male killing by a bacterial endosymbiont.

PLoS pathogens, 15(9):e1007936 pii:PPATHOGENS-D-19-01066.

Wolbachia are the most widespread maternally-transmitted bacteria in the animal kingdom. Their global spread in arthropods and varied impacts on animal physiology, evolution, and vector control are in part due to parasitic drive systems that enhance the fitness of infected females, the transmitting sex of Wolbachia. Male killing is one common drive mechanism wherein the sons of infected females are selectively killed. Despite decades of research, the gene(s) underlying Wolbachia-induced male killing remain unknown. Here using comparative genomic, transgenic, and cytological approaches in fruit flies, we identify a candidate gene in the eukaryotic association module of Wolbachia prophage WO, termed WO-mediated killing (wmk), which transgenically causes male-specific lethality during early embryogenesis and cytological defects typical of the pathology of male killing. The discovery of wmk establishes new hypotheses for the potential role of phage genes in sex-specific lethality, including the control of arthropod pests and vectors.

RevDate: 2020-01-01
CmpDate: 2020-01-01

Fisher ML, Levine JF, Guy JS, et al (2019)

Lack of influence by endosymbiont Wolbachia on virus titer in the common bed bug, Cimex lectularius.

Parasites & vectors, 12(1):436 pii:10.1186/s13071-019-3694-2.

BACKGROUND: The common bed bug, Cimex lectularius, is an obligatory blood-feeding ectoparasite that requires a blood meal to molt and produce eggs. Their frequent biting to obtain blood meals and intimate association with humans increase the potential for disease transmission. However, despite more than 100 years of inquiry into bed bugs as potential disease vectors, they still have not been conclusively linked to any pathogen or disease. This ecological niche is extraordinarily rare, given that nearly every other blood-feeding arthropod is associated with some type of human or zoonotic disease. Bed bugs rely on the bacteria Wolbachia as an obligate endosymbiont to biosynthesize B vitamins, since they acquire a nutritionally deficient diet, but it is unknown if Wolbachia confers additional benefits to its bed bug host. In some insects, Wolbachia induces resistance to viruses such as Dengue, Chikungunya, West Nile, Drosophila C and Zika, and primes the insect immune system in other blood-feeding insects. Wolbachia might have evolved a similar role in its mutualistic association with the bed bug. In this study, we evaluated the influence of Wolbachia on virus replication within C. lectularius.

METHODS: We used feline calicivirus as a model pathogen. We fed 40 bed bugs from an established line of Wolbachia-cured and a line of Wolbachia-positive C. lectularius a virus-laden blood meal, and quantified the amount of virus over five time intervals post-feeding. The antibiotic rifampicin was used to cure bed bugs of Wolbachia.

RESULTS: There was a significant effect of time post-feeding, as the amount of virus declined by ~90% over 10 days in both groups, but no significant difference in virus titer was observed between the Wolbachia-positive and Wolbachia-cured groups.

CONCLUSIONS: These findings suggest that other mechanisms are involved in virus suppression within bed bugs, independent of the influence of Wolbachia, and our conclusions underscore the need for future research.

RevDate: 2019-09-24

Iwai S, Fujita K, Takanishi Y, et al (2019)

Photosynthetic Endosymbionts Benefit from Host's Phagotrophy, Including Predation on Potential Competitors.

Current biology : CB, 29(18):3114-3119.e3.

In many endosymbioses, hosts have been shown to benefit from symbiosis, but it remains unclear whether intracellular endosymbionts benefit from their association with hosts [1, 2]. This makes it difficult to determine evolutionary mechanisms underlying cooperative behaviors between hosts and intracellular endosymbionts, such as mutual exchange of vital resources. Here, we investigate the fitness effects of symbiosis on the ciliate host Paramecium bursaria and on the algal endosymbiont Chlorella [3, 4], using experimental microcosms that include the free-living alga Chlamydomonas reinhardtii to mimic ecologically realistic conditions. We demonstrate that both host ciliate and the endosymbiotic algae gain fitness benefits from the symbiosis when another alga C. reinhardtii is present in the system. Specifically, the endosymbiotic Chlorella can grow as the host ciliate feeds and grows on C. reinhardtii, whereas the growth of free-living Chlorella is reduced by its competitor, C. reinhardtii. Thus, we propose that the endosymbiotic algae benefit from the host's phagotrophy, which allows the endosymbiont to access particulate nutrient sources and to indirectly prey on the potential competitors competing with its free-living counterparts. Even though the ecological contexts in which each partner receives its benefits differ, both partners would gain net fitness benefits in an ecological timescale. Thus, the cooperative behaviors can evolve through fitness feedback (partner fidelity feedback) between the host and the endosymbiont, without need for special partner control mechanisms. The proposed ecological and evolutionary mechanisms provide a basis for understanding cooperative resource exchanges in endosymbioses, including many photosynthetic endosymbioses widespread in aquatic ecosystems.

RevDate: 2019-09-06

Jiménez-Leiva A, Cabrera JJ, Bueno E, et al (2019)

Expanding the Regulon of the Bradyrhizobium diazoefficiens NnrR Transcription Factor: New Insights Into the Denitrification Pathway.

Frontiers in microbiology, 10:1926.

Denitrification in the soybean endosymbiont Bradyrhizobium diazoefficiens is controlled by a complex regulatory network composed of two hierarchical cascades, FixLJ-FixK2-NnrR and RegSR-NifA. In the former cascade, the CRP/FNR-type transcription factors FixK2 and NnrR exert disparate control on expression of core denitrifying systems encoded by napEDABC, nirK, norCBQD, and nosRZDFYLX genes in response to microoxia and nitrogen oxides, respectively. To identify additional genes controlled by NnrR and involved in the denitrification process in B. diazoefficiens, we compared the transcriptional profile of an nnrR mutant with that of the wild type, both grown under anoxic denitrifying conditions. This approach revealed more than 170 genes were simultaneously induced in the wild type and under the positive control of NnrR. Among them, we found the cycA gene which codes for the c550 soluble cytochrome (CycA), previously identified as an intermediate electron donor between the bc1 complex and the denitrifying nitrite reductase NirK. Here, we demonstrated that CycA is also required for nitrous oxide reductase activity. However, mutation in cycA neither affected nosZ gene expression nor NosZ protein steady-state levels. Furthermore, cycA, nnrR and its proximal divergently oriented nnrS gene, are direct targets for FixK2 as determined by in vitro transcription activation assays. The dependence of cycA expression on FixK2 and NnrR in anoxic denitrifying conditions was validated at transcriptional level, determined by quantitative reverse transcription PCR, and at the level of protein by performing heme c-staining of soluble cytochromes. Thus, this study expands the regulon of NnrR and demonstrates the role of CycA in the activity of the nitrous oxide reductase, the key enzyme for nitrous oxide mitigation.

RevDate: 2019-12-19

Christensen S, Camacho M, Sharmin Z, et al (2019)

Quantitative methods for assessing local and bodywide contributions to Wolbachia titer in maternal germline cells of Drosophila.

BMC microbiology, 19(1):206 pii:10.1186/s12866-019-1579-3.

BACKGROUND: Little is known about how bacterial endosymbionts colonize host tissues. Because many insect endosymbionts are maternally transmitted, egg colonization is critical for endosymbiont success. Wolbachia bacteria, carried by approximately half of all insect species, provide an excellent model for characterizing endosymbiont infection dynamics. To date, technical limitations have precluded stepwise analysis of germline colonization by Wolbachia. It is not clear to what extent titer-altering effects are primarily mediated by growth rates of Wolbachia within cell lineages or migration of Wolbachia between cells.

RESULTS: The objective of this work is to inform mechanisms of germline colonization through use of optimized methodology. The approaches are framed in terms of nutritional impacts on Wolbachia. Yeast-rich diets in particular have been shown to suppress Wolbachia titer in the Drosophila melanogaster germline. To determine the extent of Wolbachia sensitivity to diet, we optimized 3-dimensional, multi-stage quantification of Wolbachia titer in maternal germline cells. Technical and statistical validation confirmed the identity of Wolbachia in vivo, the reproducibility of Wolbachia quantification and the statistical power to detect these effects. The data from adult feeding experiments demonstrated that germline Wolbachia titer is distinctly sensitive to yeast-rich host diets in late oogenesis. To investigate the physiological basis for these nutritional impacts, we optimized methodology for absolute Wolbachia quantification by real-time qPCR. We found that yeast-rich diets exerted no significant effect on bodywide Wolbachia titer, although ovarian titers were significantly reduced. This suggests that host diets affects Wolbachia distribution between the soma and late stage germline cells. Notably, relative qPCR methods distorted apparent wsp abundance, due to altered host DNA copy number in yeast-rich conditions. This highlights the importance of absolute quantification data for testing mechanistic hypotheses.

CONCLUSIONS: We demonstrate that absolute quantification of Wolbachia, using well-controlled cytological and qPCR-based methods, creates new opportunities to determine how bacterial abundance within the germline relates to bacterial distribution within the body. This methodology can be applied to further test germline infection dynamics in response to chemical treatments, genetic conditions, new host/endosymbiont combinations, or potentially adapted to analyze other cell and tissue types.

RevDate: 2019-12-30
CmpDate: 2019-12-30

Li Y, Liu X, H Guo (2019)

Population Dynamics of Wolbachia in Laodelphax striatellus (Fallén) Under Successive Stress of Antibiotics.

Current microbiology, 76(11):1306-1312.

Wolbachia are the most common symbionts in arthropods; antibiotic treatment for eliminating the symbionts from their host is necessary to investigate the functions. Tetracycline antibiotics are widely used to remove endosymbiont Wolbachia from insect hosts. However, very little has been known on the effects of tetracycline on population size of Wolbachia in small brown planthopper (SBPH), Laodelphax striatellus (Fallén), an important insect pest of rice in Asia. Here, we investigated the dynamics of Wolbachia population density in females and males of L. striatellus by real-time fluorescent quantitative PCR method. The Wolbachia density in females and males of L. striatellus all declined sharply after treatment with 2 mg/mL tetracycline for one generation, and continued to decrease to a level which could not be detected by both qPCR and diagnostic PCR after treated for another generation, then maintained at 0 in the following three generations with continuous antibiotic treatment. Wolbachia infection did not recover in L. striatellus after stopping tetracycline treatment for ten generations. This is the first report to precisely monitor the population dynamics of Wolbachia in L. striatellus during successive tetracycline treatment and after that. The results provide a useful method for evaluating the efficiency of artificial operation of endosymbionts.

RevDate: 2019-11-01

Doellman MM, Schuler H, Jean GS, et al (2019)

Geographic and Ecological Dimensions of Host Plant-Associated Genetic Differentiation and Speciation in the Rhagoletis cingulata (Diptera: Tephritidae) Sibling Species Group.

Insects, 10(9):.

Ascertaining the causes of adaptive radiation is central to understanding how new species arise and come to vary with their resources. The ecological theory posits adaptive radiation via divergent natural selection associated with novel resource use; an alternative suggests character displacement following speciation in allopatry and then secondary contact of reproductively isolated but ecologically similar species. Discriminating between hypotheses, therefore, requires the establishment of a key role for ecological diversification in initiating speciation versus a secondary role in facilitating co-existence. Here, we characterize patterns of genetic variation and postzygotic reproductive isolation for tephritid fruit flies in the Rhagoletis cingulata sibling species group to assess the significance of ecology, geography, and non-adaptive processes for their divergence. Our results support the ecological theory: no evidence for intrinsic postzygotic reproductive isolation was found between two populations of allopatric species, while nuclear-encoded microsatellites implied strong ecologically based reproductive isolation among sympatric species infesting different host plants. Analysis of mitochondrial DNA suggested, however, that cytoplasmic-related reproductive isolation may also exist between two geographically isolated populations within R cingulata. Thus, ecology associated with sympatric host shifts and cytoplasmic effects possibly associated with an endosymbiont may be the key initial drivers of the radiation of the R. cingulata group.

RevDate: 2019-09-01

Ayala D, Akone-Ella O, Rahola N, et al (2019)

Natural Wolbachia infections are common in the major malaria vectors in Central Africa.

Evolutionary applications, 12(8):1583-1594 pii:EVA12804.

During the last decade, the endosymbiont bacterium Wolbachia has emerged as a biological tool for vector disease control. However, for long time, it was believed that Wolbachia was absent in natural populations of Anopheles. The recent discovery that species within the Anopheles gambiae complex host Wolbachia in natural conditions has opened new opportunities for malaria control research in Africa. Here, we investigated the prevalence and diversity of Wolbachia infection in 25 African Anopheles species in Gabon (Central Africa). Our results revealed the presence of Wolbachia in 16 of these species, including the major malaria vectors in this area. The infection prevalence varied greatly among species, confirming that sample size is a key factor to detect the infection. Moreover, our sequencing and phylogenetic analyses showed the important diversity of Wolbachia strains that infect Anopheles. Co-evolutionary analysis unveiled patterns of Wolbachia transmission within some Anopheles species, suggesting that past independent acquisition events were followed by co-cladogenesis. The large diversity of Wolbachia strains that infect natural populations of Anopheles offers a promising opportunity to select suitable phenotypes for suppressing Plasmodium transmission and/or manipulating Anopheles reproduction, which in turn could be used to reduce the malaria burden in Africa.

RevDate: 2019-08-30

Lim SJ, Alexander L, Engel AS, et al (2019)

Extensive Thioautotrophic Gill Endosymbiont Diversity within a Single Ctena orbiculata (Bivalvia: Lucinidae) Population and Implications for Defining Host-Symbiont Specificity and Species Recognition.

mSystems, 4(4): pii:4/4/e00280-19.

Seagrass-dwelling members of the bivalve family Lucinidae harbor environmentally acquired gill endosymbionts. According to previous studies, lucinid symbionts potentially represent multiple strains from a single thioautotrophic gammaproteobacterium species. This study utilized genomic- and transcriptomic-level data to resolve symbiont taxonomic, genetic, and functional diversity from Ctena orbiculata endosymbiont populations inhabiting carbonate-rich sediment at Sugarloaf Key, FL (USA). The sediment had mixed seagrass and calcareous green alga coverage and also was colonized by at least five other lucinid species. Four coexisting, thioautotrophic endosymbiont operational taxonomic units (OTUs), likely representing four strains from two different bacterial species, were identified from C. orbiculata Three of these OTUs also occurred at high relative abundances in the other sympatric lucinid species. Interspecies genetic differences averaged about 5% lower at both pairwise average nucleotide identity and amino acid identity than interstrain differences. Despite these genetic differences, C. orbiculata endosymbionts shared a high number of metabolic functions, including highly expressed thioautotrophy-related genes and a moderately to weakly expressed conserved one-carbon (C1) oxidation gene cluster previously undescribed in lucinid symbionts. Few symbiont- and host-related genes, including those encoding symbiotic sulfurtransferase, host respiratory functions, and host sulfide oxidation functions, were differentially expressed between seagrass- and alga-covered sediment locations. In contrast to previous studies, the identification of multiple endosymbiont taxa within and across C. orbiculata individuals, which were also shared with other sympatric lucinid species, suggests that neither host nor endosymbiont displays strict taxonomic specificity. This necessitates further investigations into the nature and extent of specificity of lucinid hosts and their symbionts.IMPORTANCE Symbiont diversity and host/symbiont functions have been comprehensively profiled for only a few lucinid species. In this work, unprecedented thioautotrophic gill endosymbiont taxonomic diversity was characterized within a Ctena orbiculata population associated with both seagrass- and alga-covered sediments. Endosymbiont metabolisms included known chemosynthetic functions and an additional conserved, previously uncharacterized C1 oxidation pathway. Lucinid-symbiont associations were not species specific because this C. orbiculata population hosted multiple endosymbiont strains and species, and other sympatric lucinid species shared overlapping symbiont 16S rRNA gene diversity profiles with C. orbiculata Our results suggest that lucinid-symbiont association patterns within some host species could be more taxonomically diverse than previously thought. As such, this study highlights the importance of holistic analyses, at the population, community, and even ecosystem levels, in understanding host-microbe association patterns.

RevDate: 2019-08-29

Yoder JA, Rodell BM, Klever LA, et al (2019)

Vertical transmission of the entomopathogenic soil fungus Scopulariopsis brevicaulis as a contaminant of eggs in the winter tick, Dermacentor albipictus, collected from calf moose (New Hampshire, USA).

Mycology, 10(3):174-181 pii:1600062.

Moose naturally acquire soil fungi on their fur that are entomopathogenic to the winter tick, Dermacentor albipictus. Presumed to provide a measure of on-host tick control, it is unknown whether these soil fungi impact subsequent off-host stages of the tick. Eggs and resultant larvae originating from engorged, adult female winter ticks collected from dead calf moose (Alces alces) were used to investigate the presence and extent of fungal infection. Approximately 40% of eggs and larvae were infected, almost exclusively by the fungus Scopulariopsis brevicaulis (teleomorph Microascus brevicaulis: Microascaceae, Ascomycota). Eggs analysed on the day of oviposition and day of hatching had high frequency (40%) of S. brevicaulis, whereas the frequency in eggs harvested in utero was minimal (7%); therefore, exposure occurs pre-oviposition in the female's genital chamber, not by transovarial transmission. At hatching, larvae emerge containing S. brevicaulis indicating transstadial transmission. Artificial infection by topical application of eggs and larvae with a large inoculum of S. brevicaulis spores caused rapid dehydration, marked mortality; pathogenicity was confirmed by Koch's postulates. The high hatching success (>90%) and multi-month survival of larvae imply that S. brevicaulis is maintained as a natural pathobiont in winter ticks.

RevDate: 2019-12-10
CmpDate: 2019-09-20

Genchi M, Vismarra A, Lucchetti C, et al (2019)

Efficacy of imidacloprid 10%/moxidectin 2.5% spot on (Advocate®, Advantage Multi®) and doxycycline for the treatment of natural Dirofilaria immitis infections in dogs.

Veterinary parasitology, 273:11-16.

Heartworm infection (also known as dirofilariosis due to Dirofilaria immitis) in dogs causes chronic pulmonary disease that, if left untreated, can lead to right-side congestive heart failure. Currently, the only registered drug for adulticide therapy in dogs with heartworm disease (HWD) is melarsomine dihydrochloride. The recent targeting of the bacterial endosymbiont Wolbachia, through antibiotic therapy of the infected host, has offered an interesting alternative for the treatment of HWD. Recent reports of the adulticide activity of an ivermectin/doxycycline combination protocol has lead the American Heartworm Society (AHS) to include in its guidelines that, in cases where arsenical therapy is not possible or is contraindicated, a monthly heartworm preventive along with doxycycline for a 4-week period might be considered. In the present study, 20 dogs with confirmed natural D. immitis infection were included following owner consent. Fourteen dogs were treated with a topical formulation containing 10% w/v imidacloprid and 2.5% w/v moxidectin (Advocate®, Advantage Multi®, Bayer), monthly for nine months, associated to doxycycline (10 mg/kg/BID) for the first 30 days. Six dogs were treated with melarsomine (Immiticide®, Merial) (2.5 mg/kg) at enrollment, followed one month later by two injections 24 h apart. The presence of circulating antigens and the number of microfilariae (mf) were evaluated at the moment of enrollment and then at 1, 2, 3, 4, 5, 6, 7, 8, 12, 18, 24 months post enrollment. Echocardiogram and radiographs were performed at month 0, 6, 12, 18, 24. Monthly moxidectin combined with 30 days of doxycycline eliminated circulating microfilariae within one month, thus breaking the transmission cycle very quickly. Furthermore, dogs treated with the combination protocol started to become negative for circulating antigens at 4 months from the beginning of treatment and all except one were antigen negative at 9 months. All dogs treated with melarsomine were antigen negative by 5 months from the beginning of the treatment. No dogs showed worsening of pulmonary patterns or criteria indicative of pulmonary hypertension 12 to 24 months after. For the criteria mf concentration, antigen concentration, radiography and echocardiography at 12, 18 and 24 months the non-inferiority for the moxidectin group could be proven for a non-inferiority margin of 15% for the rate difference. Dogs treated with moxidectin and doxycycline became negative for microfilariae and antigens sooner when compared to melarsomine in the present study and to dogs treated with doxycycline combined with ivermectin in studies previously published.

RevDate: 2019-09-05

Hammer TJ, NA Moran (2019)

Links between metamorphosis and symbiosis in holometabolous insects.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 374(1783):20190068.

Many animals depend on microbial symbionts to provide nutrition, defence or other services. Holometabolous insects, as well as other animals that undergo metamorphosis, face unique constraints on symbiont maintenance. Microbes present in larvae encounter a radical transformation of their habitat and may also need to withstand chemical and immunological challenges. Metamorphosis also provides an opportunity, in that symbiotic associations can be decoupled over development. For example, some holometabolous insects maintain the same symbiont as larvae and adults, but house it in different tissues; in other species, larvae and adults may harbour entirely different types or numbers of microbes, in accordance with shifts in host diet or habitat. Such flexibility may provide an advantage over hemimetabolous insects, in which selection on adult-stage microbial associations may be constrained by its negative effects on immature stages, and vice versa. Additionally, metamorphosis itself can be directly influenced by symbionts. Across disparate insect taxa, microbes protect hosts from pathogen infection, supply nutrients essential for rebuilding the adult body and provide cues regulating pupation. However, microbial associations remain completely unstudied for many families and even orders of Holometabola, and future research will undoubtedly reveal more links between metamorphosis and microbiota, two widespread features of animal life. This article is part of the theme issue 'The evolution of complete metamorphosis'.

RevDate: 2020-01-11

Mehta AP, Ko Y, Supekova L, et al (2019)

Toward a Synthetic Yeast Endosymbiont with a Minimal Genome.

Journal of the American Chemical Society, 141(35):13799-13802.

Based on the endosymbiotic theory, one of the key events that occurred during mitochondrial evolution was an extensive loss of nonessential genes from the protomitochondrial endosymbiont genome and transfer of some of the essential endosymbiont genes to the host nucleus. We have developed an approach to recapitulate various aspects of endosymbiont genome minimization using a synthetic system consisting of Escherichia coli endosymbionts within host yeast cells. As a first step, we identified a number of E. coli auxotrophs of central metabolites that can form viable endosymbionts within yeast cells. These studies provide a platform to identify nonessential biosynthetic pathways that can be deleted in the E. coli endosymbionts to investigate the evolutionary adaptations in the host and endosymbiont during the evolution of mitochondria.

RevDate: 2019-08-20

Lorenzo-Carballa MO, Torres-Cambas Y, Heaton K, et al (2019)

Widespread Wolbachia infection in an insular radiation of damselflies (Odonata, Coenagrionidae).

Scientific reports, 9(1):11933 pii:10.1038/s41598-019-47954-3.

Wolbachia is one of the most common endosymbionts found infecting arthropods. Theory predicts symbionts like Wolbachia will be more common in species radiations, as host shift events occur with greatest frequency between closely related species. Further, the presence of Wolbachia itself may engender reproductive isolation, and promote speciation of their hosts. Here we screened 178 individuals belonging to 30 species of the damselfly genera Nesobasis and Melanesobasis - species radiations endemic to the Fiji archipelago in the South Pacific - for Wolbachia, using multilocus sequence typing to characterize bacterial strains. Incidence of Wolbachia was 71% in Nesobasis and 40% in Melanesobasis, and prevalence was also high, with an average of 88% in the Nesobasis species screened. We identified a total of 25 Wolbachia strains, belonging to supergroups A, B and F, with some epidemic strains present in multiple species. The occurrence of Wolbachia in both males and females, and the similar global prevalence found in both sexes rules out any strong effect of Wolbachia on the primary sex-ratio, but are compatible with the phenotype of cytoplasmic incompatibility. Nesobasis has higher species richness than most endemic island damselfly genera, and we discuss the potential for endosymbiont-mediated speciation within this group.

RevDate: 2019-12-10
CmpDate: 2019-11-18

Youle RJ (2019)

Mitochondria-Striking a balance between host and endosymbiont.

Science (New York, N.Y.), 365(6454):.

Mitochondria are organelles with their own genome that arose from α-proteobacteria living within single-celled Archaea more than a billion years ago. This step of endosymbiosis offered tremendous opportunities for energy production and metabolism and allowed the evolution of fungi, plants, and animals. However, less appreciated are the downsides of this endosymbiosis. Coordinating gene expression between the mitochondrial genomes and the nuclear genome is imprecise and can lead to proteotoxic stress. The clonal reproduction of mitochondrial DNA requires workarounds to avoid mutational meltdown. In metazoans that developed innate immune pathways to thwart bacterial and viral infections, mitochondrial components can cross-react with pathogen sensors and invoke inflammation. Here, I focus on the numerous and elegant quality control processes that compensate for or mitigate these challenges of endosymbiosis.

RevDate: 2020-01-08

Zhu YX, Song ZR, Song YL, et al (2019)

The microbiota in spider mite feces potentially reflects intestinal bacterial communities in the host.

Insect science [Epub ahead of print].

Microorganisms provide many physiological functions to herbivorous hosts. Spider mites (genus Tetranychus) are important agricultural pests throughout the world; however, the composition of the spider mite microbial community, especially gut microbiome, remains unclear. Here, we investigated the bacterial community in five spider mite species and their associated feces by deep sequencing of the 16S rRNA gene. The composition of the bacterial community was significantly different among the five prevalent spider mite species, and some bacterial symbionts showed host-species specificity. Moreover, the abundance of the bacterial community in spider mite feces was significantly higher than that in the corresponding spider mite samples. However, Flavobacterium was detected in all samples, and represent a "core microbiome". Remarkably, the maternally inherited endosymbiont Wolbachia was detected in both spider mite and feces. Overall, these results offer insight into the complex community of symbionts in spider mites, and give a new direction for future studies.

RevDate: 2019-08-20

Swe PM, Zakrzewski M, Waddell R, et al (2019)

High-throughput metagenome analysis of the Sarcoptes scabiei internal microbiota and in-situ identification of intestinal Streptomyces sp.

Scientific reports, 9(1):11744 pii:10.1038/s41598-019-47892-0.

Multiple parasitic arthropods of medical importance depend on symbiotic bacteria. While the link between scabies and secondary bacterial infections causing post infective complications of Group A streptococcal and staphylococcal pyoderma is increasingly recognized, very little is known about the microbiota of Sarcoptes scabiei. Here we analyze adult female mite and egg metagenome datasets. The majority of adult mite bacterial reads matched with Enterobacteriaceae (phylum Proteobacteria), followed by Corynebacteriaceae (phylum Actinobacteria). Klebsiella was the most dominant genus (78%) and Corynebacterium constituted 9% of the assigned sequences. Scabies mite eggs had a more diverse microbial composition with sequences from Proteobacteria being the most dominant (75%), while Actinobacteria, Bacteroidetes and Firmicutes accounted for 23% of the egg microbiome sequences. DNA sequences of a potential endosymbiont, namely Streptomyces, were identified in the metagenome sequence data of both life stages. The presence of Streptomyces was confirmed by conventional PCR. Digital droplet PCR indicated higher Streptomyces numbers in adult mites compared to eggs. Streptomyces were localized histologically in the scabies mite gut and faecal pellets by Fluorescent In Situ Hybridization (FISH). Streptomyces may have essential symbiotic roles in the scabies parasite intestinal system requiring further investigation.

RevDate: 2019-08-13

Bockoven AA, Bondy EC, Flores MJ, et al (2019)

What Goes Up Might Come Down: the Spectacular Spread of an Endosymbiont Is Followed by Its Decline a Decade Later.

Microbial ecology pii:10.1007/s00248-019-01417-4 [Epub ahead of print].

Facultative, intracellular bacterial symbionts of arthropods may dramatically affect host biology and reproduction. The length of these symbiont-host associations may be thousands to millions of years, and while symbiont loss is predicted, there have been very few observations of a decline of symbiont infection rates. In a population of the sweet potato whitefly species (Bemisia tabaci MEAM1) in Arizona, USA, we documented the frequency decline of a strain of Rickettsia in the Rickettsia bellii clade from near-fixation in 2011 to 36% of whiteflies infected in 2017. In previous studies, Rickettsia had been shown to increase from 1 to 97% from 2000 to 2006 and remained at high frequency for at least five years. At that time, Rickettsia infection was associated with both fitness benefits and female bias. In the current study, we established matrilines of whiteflies from the field (2016, Rickettsia infection frequency = 58%) and studied (a) Rickettsia vertical transmission, (b) fitness and sex ratios associated with Rickettsia infection, (c) symbiont titer, and (d) bacterial communities within whiteflies. The vertical transmission rate was high, approximately 98%. Rickettsia infection in the matrilines was not associated with fitness benefits or sex ratio bias and appeared to be slightly costly, as more Rickettsia-infected individuals produced non-hatching eggs. Overall, the titer of Rickettsia in the matrilines was lower in 2016 than in the whiteflies collected in 2011, but the titer distribution appeared bimodal, with high- and low-titer lines, and constancy of the average titer within lines over three generations. We found neither association between Rickettsia titer and fitness benefits or sex ratio bias nor evidence that Rickettsia was replaced by another secondary symbiont. The change in the interaction between symbiont and host in 2016 whiteflies may explain the drop in symbiont frequency we observed.

RevDate: 2019-10-23

Serra V, Krey V, Daschkin C, et al (2019)

Seropositivity to Midichloria mitochondrii (order Rickettsiales) as a marker to determine the exposure of humans to tick bite.

Pathogens and global health, 113(4):167-172.

Ixodes ricinus is the most common tick species parasitizing humans in Europe, and the main vector of Borrelia burgdorferi sensu lato, the causative agent of Lyme disease in the continent. This tick species also harbors the endosymbiont Midichloria mitochondrii, and there is strong evidence that this bacterium is inoculated into the vertebrate host during the blood meal. A high proportion of tick bites remains unnoticed due to rarity of immediate symptoms, implying the risk of occult tick-borne infections in turn a potential risk factor for the onset of chronic-degenerative diseases. Since suitable tools to determine the previous exposure to I. ricinus bites are needed, this work investigated whether seropositivity toward a protein of M. mitochondrii (rFliD) could represent a marker for diagnosis of I. ricinus bite. We screened 274 sera collected from patients from several European countries, at different risk of tick bite, using an ELISA protocol. Our results show a clear trend indicating that positivity to rFliD is higher where the tick bite can be regarded as certain/almost certain, and lower where there is an uncertainty on the bite, with the highest positivity in Lyme patients (47.30%) and the lowest (2.00%) in negative controls. According to the obtained results, M. mitochondrii can be regarded as a useful source of antigens, with the potential to be used to assess the exposure to ticks harboring this bacterium. In prospect, additional antigens from M. mitochondrii and tick salivary glands should be investigated and incorporated in a multi-antigen test for tick bite diagnosis.

RevDate: 2019-08-11

Liu L, Zhang KJ, Rong X, et al (2019)

Identification of Wolbachia-Responsive miRNAs in the Small Brown Planthopper, Laodelphax striatellus.

Frontiers in physiology, 10:928.

Laodelphax striatellus is naturally infected with the Wolbachia strain wStri, which induces strong cytoplasmic incompatibility of its host. MicroRNAs (miRNAs) are a class of endogenous non-coding small RNAs that play a critical role in the regulation of gene expression at post-transcriptional level in various biological processes. Despite various studies reporting that Wolbachia affects the miRNA expression of their hosts, the molecular mechanism underlying interactions between Wolbachia and their host miRNAs has not been well understood. In order to better understand the impact of Wolbachia infection on its host, we investigated the differentially expressed miRNAs between Wolbachia-infected and Wolbachia-uninfected strains of L. striatellus. Compared with uninfected strains, Wolbachia infection resulted in up-regulation of 18 miRNAs and down-regulation of 6 miRNAs in male, while 25 miRNAs were up-regulated and 15 miRNAs were down-regulated in female. The target genes of these differentially expressed miRNAs involved in immune response regulation, reproduction, redox homeostasis and ecdysteroidogenesis were also annotated in both sexes. We further verified the expression of several significantly differentially expressed miRNAs and their predicted target genes by qRT-PCR method. The results suggested that Wolbachia appears to reduce the expression of genes related to fertility in males and increase the expression of genes related to fecundity in females. At the same time, Wolbachia may enhance the expression of immune-related genes in both sexes. All of the results in this study may be helpful in further exploration of the molecular mechanisms by which Wolbachia affects on its hosts.


ESP Quick Facts

ESP Origins

In the early 1990's, Robert Robbins was a faculty member at Johns Hopkins, where he directed the informatics core of GDB — the human gene-mapping database of the international human genome project. To share papers with colleagues around the world, he set up a small paper-sharing section on his personal web page. This small project evolved into The Electronic Scholarly Publishing Project.

ESP Support

In 1995, Robbins became the VP/IT of the Fred Hutchinson Cancer Research Center in Seattle, WA. Soon after arriving in Seattle, Robbins secured funding, through the ELSI component of the US Human Genome Project, to create the original ESP.ORG web site, with the formal goal of providing free, world-wide access to the literature of classical genetics.

ESP Rationale

Although the methods of molecular biology can seem almost magical to the uninitiated, the original techniques of classical genetics are readily appreciated by one and all: cross individuals that differ in some inherited trait, collect all of the progeny, score their attributes, and propose mechanisms to explain the patterns of inheritance observed.

ESP Goal

In reading the early works of classical genetics, one is drawn, almost inexorably, into ever more complex models, until molecular explanations begin to seem both necessary and natural. At that point, the tools for understanding genome research are at hand. Assisting readers reach this point was the original goal of The Electronic Scholarly Publishing Project.

ESP Usage

Usage of the site grew rapidly and has remained high. Faculty began to use the site for their assigned readings. Other on-line publishers, ranging from The New York Times to Nature referenced ESP materials in their own publications. Nobel laureates (e.g., Joshua Lederberg) regularly used the site and even wrote to suggest changes and improvements.

ESP Content

When the site began, no journals were making their early content available in digital format. As a result, ESP was obliged to digitize classic literature before it could be made available. For many important papers — such as Mendel's original paper or the first genetic map — ESP had to produce entirely new typeset versions of the works, if they were to be available in a high-quality format.

ESP Help

Early support from the DOE component of the Human Genome Project was critically important for getting the ESP project on a firm foundation. Since that funding ended (nearly 20 years ago), the project has been operated as a purely volunteer effort. Anyone wishing to assist in these efforts should send an email to Robbins.

ESP Plans

With the development of methods for adding typeset side notes to PDF files, the ESP project now plans to add annotated versions of some classical papers to its holdings. We also plan to add new reference and pedagogical material. We have already started providing regularly updated, comprehensive bibliographies to the ESP.ORG site.

Electronic Scholarly Publishing
961 Red Tail Lane
Bellingham, WA 98226

E-mail: RJR8222 @

Papers in Classical Genetics

The ESP began as an effort to share a handful of key papers from the early days of classical genetics. Now the collection has grown to include hundreds of papers, in full-text format.

Digital Books

Along with papers on classical genetics, ESP offers a collection of full-text digital books, including many works by Darwin (and even a collection of poetry — Chicago Poems by Carl Sandburg).


ESP now offers a much improved and expanded collection of timelines, designed to give the user choice over subject matter and dates.


Biographical information about many key scientists.

Selected Bibliographies

Bibliographies on several topics of potential interest to the ESP community are now being automatically maintained and generated on the ESP site.

ESP Picks from Around the Web (updated 07 JUL 2018 )