Journal articles on the topic 'Bacterial symbiont'
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Murti, Damar Bayu, A. B. Susanto, Ocky Karna Radjasa, and Ferdy Semuel Rondonuwu. "Pigments Characterization and Molecular Identification of Bacterial Symbionts of Brown Algae Padinasp. Collected from Karimunjawa Island." ILMU KELAUTAN: Indonesian Journal of Marine Sciences 21, no. 2 (June 1, 2016): 58. http://dx.doi.org/10.14710/ik.ijms.21.2.58-64.
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The search for carotenoids in nature has been extensively studied because of their applications in foods. One treasure of the biopigment source is symbiotic-microorganisms with marine biota. The advantages of symbiont bacteria are easy to culture and sensitize pigments. The use of symbiont bacteria helps to conserve fish, coral reefs, seagrass, and seaweed. Therefore, the bacteria keeps their existence in their ecosystems. In this study, bacterial symbionts were successfully isolated from brown algae Padina sp. The bacterial symbionts had yellow pigment associated with carotenoids. The pigments were characterized using High Performance Liquid Chromatography (HPLC) with a Photo Diode Array (PDA) detector. The carotenoid pigments in the bacterial symbionts were identified as dinoxanthin, lutein and neoxanthin. Molecular identification by using a 16S rRNA gene sequence method, reveals that the bacterial symbionts were closely related to Bacillus marisflavi with a homology of 99%. Keywords :carotenoid pigments, brown algae, Padina, bacterial symbionts, 16S rRNA
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Sipe, Alison R., Ami E. Wilbur, and S. Craig Cary. "Bacterial Symbiont Transmission in the Wood-Boring Shipworm Bankia setacea (Bivalvia: Teredinidae)." Applied and Environmental Microbiology 66, no. 4 (April 1, 2000): 1685–91. http://dx.doi.org/10.1128/aem.66.4.1685-1691.2000.
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ABSTRACT The Teredinidae (shipworms) are a morphologically diverse group of marine wood-boring bivalves that are responsible each year for millions of dollars of damage to wooden structures in estuarine and marine habitats worldwide. They exist in a symbiosis with cellulolytic nitrogen-fixing bacteria that provide the host with the necessary enzymes for survival on a diet of wood cellulose. These symbiotic bacteria reside in distinct structures lining the interlamellar junctions of the gill. This study investigated the mode by which these nutritionally essential bacterial symbionts are acquired in the teredinid Bankia setacea. Through 16S ribosomal DNA (rDNA) sequencing, the symbiont residing within the B. setaceagill was phylogenetically characterized and shown to be distinct from previously described shipworm symbionts. In situ hybridization using symbiont-specific 16S rRNA-directed probes bound to bacterial ribosome targets located within the host gill coincident with the known location of the gill symbionts. These specific probes were then used as primers in a PCR-based assay which consistently detected bacterial rDNA in host gill (symbiont containing), gonad tissue, and recently spawned eggs, demonstrating the presence of symbiont cells in host ovary and offspring. These results suggest that B. setacea ensures successful inoculation of offspring through a vertical mode of symbiont transmission and thereby enables a broad distribution of larval settlement.
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Matsuura, Yu, Takahiro Hosokawa, Mario Serracin, Genet M. Tulgetske, Thomas A. Miller, and Takema Fukatsu. "Bacterial Symbionts of a Devastating Coffee Plant Pest, the Stinkbug Antestiopsis thunbergii (Hemiptera: Pentatomidae)." Applied and Environmental Microbiology 80, no. 12 (April 11, 2014): 3769–75. http://dx.doi.org/10.1128/aem.00554-14.
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ABSTRACTStinkbugs of the genusAntestiopsis, so-called antestia bugs or variegated coffee bugs, are notorious pests of coffee plants in Africa. We investigated the symbiotic bacteria associated withAntestiopsis thunbergii, a major coffee plant pest in Rwanda. PCR, cloning, sequencing, and phylogenetic analysis of bacterial genes identified four distinct bacterial lineages associated withA. thunbergii: a gammaproteobacterial gut symbiont and symbionts representing the generaSodalis,Spiroplasma, andRickettsia.In situhybridization showed that the gut symbiont densely occupied the lumen of midgut crypts, whereas theSodalissymbiont, theSpiroplasmasymbiont, and theRickettsiasymbiont sparsely and sporadically infected various cells and tissues. Diagnostic PCR survey of 154A. thunbergiiindividuals collected at 8 localities in Rwanda revealed high infection frequencies (100% for the gut symbiont, 51.3% for theSodalissymbiont, 52.6% for theSpiroplasmasymbiont, and 24.0% for theRickettsiasymbiont). These results suggest that the gut symbiont is the primary symbiotic associate of obligate nature forA. thunbergii, whereas theSodalissymbiont, theSpiroplasmasymbiont, and theRickettsiasymbiont are the secondary symbiotic associates of facultative nature. We observed high coinfection frequencies, i.e., 7.8% of individuals with quadruple infection with all the symbionts, 32.5% with triple infections with the gut symbiont and two of the secondary symbionts, and 39.6% with double infections with the gut symbiont and any of the three secondary symbionts, which were statistically not different from the expected coinfection frequencies and probably reflected random associations. The knowledge of symbiotic microbiota inA. thunbergiiwill provide useful background information for controlling this devastating coffee plant pest.
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Xu, Ting-Ting, Li-Yun Jiang, Jing Chen, and Ge-Xia Qiao. "Host Plants Influence the Symbiont Diversity of Eriosomatinae (Hemiptera: Aphididae)." Insects 11, no. 4 (April 1, 2020): 217. http://dx.doi.org/10.3390/insects11040217.
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Eriosomatinae is a particular aphid group with typically heteroecious holocyclic life cycle, exhibiting strong primary host plant specialization and inducing galls on primary host plants. Aphids are frequently associated with bacterial symbionts, which can play fundamental roles in the ecology and evolution of their host aphids. However, the bacterial communities in Eriosomatinae are poorly known. In the present study, using high-throughput sequencing of the bacterial 16S ribosomal RNA gene, we surveyed the bacterial flora of eriosomatines and explored the associations between symbiont diversity and aphid relatedness, aphid host plant and geographical distribution. The microbiota of Eriosomatinae is dominated by the heritable primary endosymbiont Buchnera and several facultative symbionts. The primary endosymbiont Buchnera is expectedly the most abundant symbiont across all species. Six facultative symbionts were identified. Regiella was the most commonly identified facultative symbiont, and multiple infections of facultative symbionts were detected in the majority of the samples. Ordination analyses and statistical tests show that the symbiont community of aphids feeding on plants from the family Ulmaceae were distinguishable from aphids feeding on other host plants. Species in Eriosomatinae feeding on different plants are likely to carry different symbiont compositions. The symbiont distributions seem to be not related to taxonomic distance and geographical distance. Our findings suggest that host plants can affect symbiont maintenance, and will improve our understanding of the interactions between aphids, their symbionts and ecological conditions.
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Gómez-Valero, Laura, Mario Soriano-Navarro, Vicente Pérez-Brocal, Abdelaziz Heddi, Andrés Moya, José Manuel García-Verdugo, and Amparo Latorre. "Coexistence of Wolbachia with Buchnera aphidicola and a Secondary Symbiont in the Aphid Cinara cedri." Journal of Bacteriology 186, no. 19 (October 1, 2004): 6626–33. http://dx.doi.org/10.1128/jb.186.19.6626-6633.2004.
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ABSTRACT Intracellular symbiosis is very common in the insect world. For the aphid Cinara cedri, we have identified by electron microscopy three symbiotic bacteria that can be characterized by their different sizes, morphologies, and electrodensities. PCR amplification and sequencing of the 16S ribosomal DNA (rDNA) genes showed that, in addition to harboring Buchnera aphidicola, the primary endosymbiont of aphids, C. cedri harbors a secondary symbiont (S symbiont) that was previously found to be associated with aphids (PASS, or R type) and an α-proteobacterium that belongs to the Wolbachia genus. Using in situ hybridization with specific bacterial probes designed for symbiont 16S rDNA sequences, we have shown that Wolbachia was represented by only a few minute bacteria surrounding the S symbionts. Moreover, the observed B. aphidicola and the S symbionts had similar sizes and were housed in separate specific bacterial cells, the bacteriocytes. Interestingly, in contrast to the case for all aphids examined thus far, the S symbionts were shown to occupy a similarly sized or even larger bacteriocyte space than B. aphidicola. These findings, along with the facts that C. cedri harbors the B. aphidicola strain with the smallest bacterial genome and that the S symbionts infect all Cinara spp. analyzed so far, suggest the possibility of bacterial replacement in these species.
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Ohbayashi, Tsubasa, Kazutaka Takeshita, Wataru Kitagawa, Naruo Nikoh, Ryuichi Koga, Xian-Ying Meng, Kanako Tago, et al. "Insect’s intestinal organ for symbiont sorting." Proceedings of the National Academy of Sciences 112, no. 37 (August 31, 2015): E5179—E5188. http://dx.doi.org/10.1073/pnas.1511454112.
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Symbiosis has significantly contributed to organismal adaptation and diversification. For establishment and maintenance of such host–symbiont associations, host organisms must have evolved mechanisms for selective incorporation, accommodation, and maintenance of their specific microbial partners. Here we report the discovery of a previously unrecognized type of animal organ for symbiont sorting. In the bean bug Riptortus pedestris, the posterior midgut is morphologically differentiated for harboring specific symbiotic bacteria of a beneficial nature. The sorting organ lies in the middle of the intestine as a constricted region, which partitions the midgut into an anterior nonsymbiotic region and a posterior symbiotic region. Oral administration of GFP-labeled Burkholderia symbionts to nymphal stinkbugs showed that the symbionts pass through the constricted region and colonize the posterior midgut. However, administration of food colorings revealed that food fluid enters neither the constricted region nor the posterior midgut, indicating selective symbiont passage at the constricted region and functional isolation of the posterior midgut for symbiosis. Coadministration of the GFP-labeled symbiont and red fluorescent protein-labeled Escherichia coli unveiled selective passage of the symbiont and blockage of E. coli at the constricted region, demonstrating the organ’s ability to discriminate the specific bacterial symbiont from nonsymbiotic bacteria. Transposon mutagenesis and screening revealed that symbiont mutants in flagella-related genes fail to pass through the constricted region, highlighting that both host’s control and symbiont’s motility are involved in the sorting process. The blocking of food flow at the constricted region is conserved among diverse stinkbug groups, suggesting the evolutionary origin of the intestinal organ in their common ancestor.
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Xu, Shifen, Liyun Jiang, Gexia Qiao, and Jing Chen. "The Bacterial Flora Associated with the Polyphagous Aphid Aphis gossypii Glover (Hemiptera: Aphididae) Is Strongly Affected by Host Plants." Microbial Ecology 79, no. 4 (December 4, 2019): 971–84. http://dx.doi.org/10.1007/s00248-019-01435-2.
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AbstractAphids live in symbiosis with a variety of bacteria, including the obligate symbiont Buchnera aphidicola and diverse facultative symbionts. The symbiotic associations for one aphid species, especially for polyphagous species, often differ across populations. In the present study, by using high-throughput 16S rRNA sequencing, we surveyed in detail the microbiota in natural populations of the cotton aphid Aphis gossypii in China and assessed differences in bacterial diversity with respect to host plant and geography. The microbial community of A. gossypii was dominated by a few heritable symbionts. Arsenophonus was the most dominant secondary symbiont, and Spiroplasma was detected for the first time. Statistical tests and ordination analyses showed that host plants rather than geography seemed to have shaped the associated symbiont composition. Special symbiont communities inhabited the Cucurbitaceae-feeding populations, which supported the ecological specialization of A. gossypii on cucurbits from the viewpoint of symbiotic bacteria. Correlation analysis suggested antagonistic interactions between Buchnera and coexisting secondary symbionts and more complicated interactions between different secondary symbionts. Our findings lend further support to an important role of the host plant in structuring symbiont communities of polyphagous aphids and will improve our understanding of the interactions among phytophagous insects, symbionts, and environments.
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Ashen, Jon B., and Lynda J. Goff. "Molecular and Ecological Evidence for Species Specificity and Coevolution in a Group of Marine Algal-Bacterial Symbioses." Applied and Environmental Microbiology 66, no. 7 (July 1, 2000): 3024–30. http://dx.doi.org/10.1128/aem.66.7.3024-3030.2000.
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ABSTRACT The phylogenetic relationships of bacterial symbionts from three gall-bearing species in the marine red algal genusPrionitis (Rhodophyta) were inferred from 16S rDNA sequence analysis and compared to host phylogeny also inferred from sequence comparisons (nuclear ribosomal internal-transcribed-spacer region). Gall formation has been described previously on two species ofPrionitis, P. lanceolata (from central California) and P. decipiens (from Peru). This investigation reports gall formation on a third related host,Prionitis filiformis. Phylogenetic analyses based on sequence comparisons place the bacteria as a single lineage within theRoseobacter grouping of the α subclass of the divisionProteobacteria (99.4 to 98.25% sequence identity among phylotypes). Comparison of symbiont and host molecular phylogenies confirms the presence of three gall-bearing algal lineages and is consistent with the hypothesis that these red seaweeds and their bacterial symbionts are coevolving. The species specificity of these associations was investigated in nature by whole-cell hybridization of gall bacteria and in the laboratory by using cross-inoculation trials. Whole-cell in situ hybridization confirmed that a single bacterial symbiont phylotype is present in galls on each host. In laboratory trials, bacterial symbionts were incapable of inducing galls on alternate hosts (including two non-gall-bearing species). Symbiont-host specificity in Prionitis gall formation indicates an effective ecological separation between these closely related symbiont phylotypes and provides an example of a biological context in which to consider the organismic significance of 16S rDNA sequence variation.
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Erwin, Patrick M., Lucía Pita, Susanna López-Legentil, and Xavier Turon. "Stability of Sponge-Associated Bacteria over Large Seasonal Shifts in Temperature and Irradiance." Applied and Environmental Microbiology 78, no. 20 (August 10, 2012): 7358–68. http://dx.doi.org/10.1128/aem.02035-12.
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ABSTRACTComplex microbiomes reside in marine sponges and consist of diverse microbial taxa, including functional guilds that may contribute to host metabolism and coastal marine nutrient cycles. Our understanding of these symbiotic systems is based primarily on static accounts of sponge microbiota, while their temporal dynamics across seasonal cycles remain largely unknown. Here, we investigated temporal variation in bacterial symbionts of three sympatric sponges (Irciniaspp.) over 1.5 years in the northwestern (NW) Mediterranean Sea, using replicated terminal restriction fragment length polymorphism (T-RFLP) and clone library analyses of bacterial 16S rRNA gene sequences. Bacterial symbionts inIrciniaspp. exhibited host species-specific structure and remarkable stability throughout the monitoring period, despite large fluctuations in temperature and irradiance. In contrast, seawater bacteria exhibited clear seasonal shifts in community structure, indicating that different ecological constraints act on free-living and on symbiotic marine bacteria. Symbiont profiles were dominated by persistent, sponge-specific bacterial taxa, notably affiliated with phylogenetic lineages capable of photosynthesis, nitrite oxidation, and sulfate reduction. Variability in the sponge microbiota was restricted to rare symbionts and occurred most prominently in warmer seasons, coincident with elevated thermal regimes. Seasonal stability of the sponge microbiota supports the hypothesis of host-specific, stable associations between bacteria and sponges. Further, the core symbiont profiles revealed in this study provide an empirical baseline for diagnosing abnormal shifts in symbiont communities. Considering that these sponges have suffered recent, episodic mass mortalities related to thermal stresses, this study contributes to the development of model sponge-microbe symbioses for assessing the link between symbiont fluctuations and host health.
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Moran, Nancy A., Phat Tran, and Nicole M. Gerardo. "Symbiosis and Insect Diversification: an Ancient Symbiont of Sap-Feeding Insects from the Bacterial Phylum Bacteroidetes." Applied and Environmental Microbiology 71, no. 12 (December 2005): 8802–10. http://dx.doi.org/10.1128/aem.71.12.8802-8810.2005.
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ABSTRACT Several insect groups have obligate, vertically transmitted bacterial symbionts that provision hosts with nutrients that are limiting in the diet. Some of these bacteria have been shown to descend from ancient infections. Here we show that the large group of related insects including cicadas, leafhoppers, treehoppers, spittlebugs, and planthoppers host a distinct clade of bacterial symbionts. This newly described symbiont lineage belongs to the phylum Bacteroidetes. Analyses of 16S rRNA genes indicate that the symbiont phylogeny is completely congruent with the phylogeny of insect hosts as currently known. These results support the ancient acquisition of a symbiont by a shared ancestor of these insects, dating the original infection to at least 260 million years ago. As visualized in a species of spittlebug (Cercopoidea) and in a species of sharpshooter (Cicadellinae), the symbionts have extraordinarily large cells with an elongate shape, often more than 30 μm in length; in situ hybridizations verify that these correspond to the phylum Bacteroidetes. “Candidatus Sulcia muelleri” is proposed as the name of the new symbiont.
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Kaiwa, Nahomi, Takahiro Hosokawa, Yoshitomo Kikuchi, Naruo Nikoh, Xian Ying Meng, Nobutada Kimura, Motomi Ito, and Takema Fukatsu. "Primary Gut Symbiont and Secondary, Sodalis-Allied Symbiont of the Scutellerid Stinkbug Cantao ocellatus." Applied and Environmental Microbiology 76, no. 11 (April 16, 2010): 3486–94. http://dx.doi.org/10.1128/aem.00421-10.
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ABSTRACT Symbiotic associations with midgut bacteria have been commonly found in diverse phytophagous heteropteran groups, where microbiological characterization of the symbiotic bacteria has been restricted to the stinkbug families Acanthosomatidae, Plataspidae, Pentatomidae, Alydidae, and Pyrrhocoridae. Here we investigated the midgut bacterial symbiont of Cantao ocellatus, a stinkbug of the family Scutelleridae. A specific gammaproteobacterium was consistently identified from the insects of different geographic origins. The bacterium was detected in all 116 insects collected from 9 natural host populations. Phylogenetic analyses revealed that the bacterium constitutes a distinct lineage in the Gammaproteobacteria, not closely related to gut symbionts of other stinkbugs. Diagnostic PCR and in situ hybridization demonstrated that the bacterium is extracellularly located in the midgut 4th section with crypts. Electron microscopy of the crypts revealed a peculiar histological configuration at the host-symbiont interface. Egg sterilization experiments confirmed that the bacterium is vertically transmitted to stinkbug nymphs via egg surface contamination. In addition to the gut symbiont, some individuals of C. ocellatus harbored another bacterial symbiont in their gonads, which was closely related to Sodalis glossinidius, the secondary endosymbiont of tsetse flies. Biological aspects of the primary gut symbiont and the secondary Sodalis-allied symbiont are discussed.
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McLean, A. H. C., M. van Asch, J. Ferrari, and H. C. J. Godfray. "Effects of bacterial secondary symbionts on host plant use in pea aphids." Proceedings of the Royal Society B: Biological Sciences 278, no. 1706 (September 15, 2010): 760–66. http://dx.doi.org/10.1098/rspb.2010.1654.
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Aphids possess several facultative bacterial symbionts that have important effects on their hosts' biology. These have been most closely studied in the pea aphid ( Acyrthosiphon pisum ), a species that feeds on multiple host plants. Whether secondary symbionts influence host plant utilization is unclear. We report the fitness consequences of introducing different strains of the symbiont Hamiltonella defensa into three aphid clones collected on Lathyrus pratensis that naturally lack symbionts, and of removing symbionts from 20 natural aphid–bacterial associations. Infection decreased fitness on Lathyrus but not on Vicia faba , a plant on which most pea aphids readily feed. This may explain the unusually low prevalence of symbionts in aphids collected on Lathyrus . There was no effect of presence of symbiont on performance of the aphids on the host plants of the clones from which the H. defensa strains were isolated. Removing the symbiont from natural aphid–bacterial associations led to an average approximate 20 per cent reduction in fecundity, both on the natural host plant and on V. faba , suggesting general rather than plant-species-specific effects of the symbiont. Throughout, we find significant genetic variation among aphid clones. The results provide no evidence that secondary symbionts have a major direct role in facilitating aphid utilization of particular host plant species.
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McCuaig, Bonita, France Liboiron, and Suzanne C. Dufour. "The bivalveThyasiracf.gouldihosts chemoautotrophic symbiont populations with strain level diversity." PeerJ 5 (July 26, 2017): e3597. http://dx.doi.org/10.7717/peerj.3597.
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Invertebrates from various marine habitats form nutritional symbioses with chemosynthetic bacteria. In chemosynthetic symbioses, both the mode of symbiont transmission and the site of bacterial housing can affect the composition of the symbiont population. Vertically transmitted symbionts, as well as those hosted intracellularly, are more likely to form clonal populations within their host. Conversely, symbiont populations that are environmentally acquired and extracellular may be more likely to be heterogeneous/mixed within host individuals, as observed in some mytilid bivalves. The symbionts of thyasirid bivalves are also extracellular, but limited 16S rRNA sequencing data suggest that thyasirid individuals contain uniform symbiont populations. In a recent study,Thyasiracf.gouldiindividuals from Bonne Bay, Newfoundland, Canada were found to host one of three 16S rRNA phylotypes of sulfur-oxidizing gammaproteobacteria, suggesting environmental acquisition of symbionts and some degree of site-specificity. Here, we use Sanger sequencing of both 16S RNA and the more variable ribulose-1,5-bisphosphate carboxylase (RuBisCO) PCR products to further examineThyasiracf.gouldisymbiont diversity at the scale of host individuals, as well as to elucidate any temporal or spatial patterns in symbiont diversity within Bonne Bay, and relationships with host OTU or size. We obtained symbiont 16S rRNA and RuBisCO Form II sequences from 54 and 50 host individuals, respectively, during nine sampling trips to three locations over four years. Analyses uncovered the same three closely related 16S rRNA phylotypes obtained previously, as well as three divergent RuBisCO phylotypes; these were found in various pair combinations within host individuals, suggesting incidents of horizontal gene transfer during symbiont evolution. While we found no temporal patterns in phylotype distribution or relationships with host OTU or size, some spatial effects were noted, with some phylotypes only found within particular sampling sites. The sequencing also revealed symbiont populations within individual hosts that appeared to be a mixture of different phylotypes, based on multiple base callings at divergent sites. This work provides further evidence thatThyasiracf.gouldiacquires its symbionts from the environment, and supports the theory that hosts can harbour symbiont populations consisting of multiple, closely related bacterial phylotypes.
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Gehrer, Lukas, and Christoph Vorburger. "Parasitoids as vectors of facultative bacterial endosymbionts in aphids." Biology Letters 8, no. 4 (March 14, 2012): 613–15. http://dx.doi.org/10.1098/rsbl.2012.0144.
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Heritable bacterial endosymbionts play an important role in aphid ecology. Sequence-based evidence suggests that facultative symbionts such as Hamiltonella defensa or Regiella insecticola also undergo horizontal transmission. Other than through male-to-female transfer during the sexual generation in autumn, the routes by which this occurs remain largely unknown. Here, we tested if parasitoids or ectoparasitic mites can act as vectors for horizontal transfer of facultative symbionts. Using symbiont-specific primers for diagnostic PCR, we demonstrate for the first time, to our knowledge, that parasitoids can indeed transfer H. defensa and R. insecticola by sequentially stabbing infected and uninfected individuals of their host, Aphis fabae , establishing new, heritable infections. Thus, a natural route of horizontal symbiont transmission is also available during the many clonal generations of the aphid life cycle. No transmissions by ectoparasitic mites were observed, nor did parasitoids that emerged from symbiont-infected aphids transfer any symbionts in our experiments.
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Hosokawa, Takahiro, Yoshitomo Kikuchi, Naruo Nikoh, Xian-Ying Meng, Mantaro Hironaka, and Takema Fukatsu. "Phylogenetic Position and Peculiar Genetic Traits of a Midgut Bacterial Symbiont of the Stinkbug Parastrachia japonensis." Applied and Environmental Microbiology 76, no. 13 (May 7, 2010): 4130–35. http://dx.doi.org/10.1128/aem.00616-10.
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ABSTRACT The stinkbug Parastrachia japonensis (Hemiptera: Parastrachiidae) is known for its prolonged prereproductive nonfeeding period, maternal care of eggs in an underground nest, and maternal collection and provisioning of food (fruits) for nymphs. A previous study suggested that a bacterial symbiont is involved in uric acid recycling in this insect during the nonfeeding period, but the identity of this symbiont has not been determined. Here we characterized a novel bacterial symbiont obtained from P. japonensis. Molecular phylogenetic analyses based on 16S rRNA, gyrB, and groEL gene sequences consistently indicated that this symbiont constituted a distinct lineage in the Gammaproteobacteria that has no close relatives but is allied with gut symbionts of acanthosomatid and plataspid stinkbugs, as well as with endocellular symbionts of sharpshooters, tsetse flies, and aphids. The symbiont genes had a remarkably AT-biased nucleotide composition and exhibited significantly accelerated molecular evolution. The symbiont genome was extremely reduced; its size was estimated to be 0.85 Mb. These results suggest that there has been an intimate host-symbiont association over evolutionary time. The symbiont was localized in swollen crypts in a posterior part of the midgut, which was a specialized symbiotic organ. The possibility that the symbiont is involved in uric acid recycling is discussed. The designation “Candidatus Benitsuchiphilus tojoi” is proposed for the symbiont.
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Carpenter, Melissa, Linyao Peng, Andrew H. Smith, Jonah Joffe, Michael O’Connor, Kerry M. Oliver, and Jacob A. Russell. "Frequent Drivers, Occasional Passengers: Signals of Symbiont-Driven Seasonal Adaptation and Hitchhiking in the Pea Aphid, Acyrthosiphon pisum." Insects 12, no. 9 (September 8, 2021): 805. http://dx.doi.org/10.3390/insects12090805.
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Insects harbor a variety of maternally inherited bacterial symbionts. As such, variation in symbiont presence/absence, in the combinations of harbored symbionts, and in the genotypes of harbored symbiont species provide heritable genetic variation of potential use in the insects’ adaptive repertoires. Understanding the natural importance of symbionts is challenging but studying their dynamics over time can help to elucidate the potential for such symbiont-driven insect adaptation. Toward this end, we studied the seasonal dynamics of six maternally transferred bacterial symbiont species in the multivoltine pea aphid (Acyrthosiphon pisum). Our sampling focused on six alfalfa fields in southeastern Pennsylvania, and spanned 14 timepoints within the 2012 growing season, in addition to two overwintering periods. To test and generate hypotheses on the natural relevance of these non-essential symbionts, we examined whether symbiont dynamics correlated with any of ten measured environmental variables from the 2012 growing season, including some of known importance in the lab. We found that five symbionts changed prevalence across one or both overwintering periods, and that the same five species underwent such frequency shifts across the 2012 growing season. Intriguingly, the frequencies of these dynamic symbionts showed robust correlations with a subset of our measured environmental variables. Several of these trends supported the natural relevance of lab-discovered symbiont roles, including anti-pathogen defense. For a seventh symbiont—Hamiltonella defensa—studied previously across the same study periods, we tested whether a reported correlation between prevalence and temperature stemmed not from thermally varying host-level fitness effects, but from selection on co-infecting symbionts or on aphid-encoded alleles associated with this bacterium. In general, such “hitchhiking” effects were not evident during times with strongly correlated Hamiltonella and temperature shifts. However, we did identify at least one time period in which Hamiltonella spread was likely driven by selection on a co-infecting symbiont—Rickettsiella viridis. Recognizing the broader potential for such hitchhiking, we explored selection on co-infecting symbionts as a possible driver behind the dynamics of the remaining six species. Out of twelve examined instances of symbiont dynamics unfolding across 2-week periods or overwintering spans, we found eight in which the focal symbiont underwent parallel frequency shifts under single infection and one or more co-infection contexts. This supported the idea that phenotypic variation created by the presence/absence of individual symbionts is a direct target for selection, and that symbiont effects can be robust under co-habitation with other symbionts. Contrastingly, in two cases, we found that selection may target phenotypes emerging from symbiont co-infections, with specific species combinations driving overall trends for the focal dynamic symbionts, without correlated change under single infection. Finally, in three cases—including the one described above for Hamiltonella—our data suggested that incidental co-infection with a (dis)favored symbiont could lead to large frequency shifts for “passenger” symbionts, conferring no apparent cost or benefit. Such hitchhiking has rarely been studied in heritable symbiont systems. We propose that it is more common than appreciated, given the widespread nature of maternally inherited bacteria, and the frequency of multi-species symbiotic communities across insects.
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Husnik, Filip, and John P. McCutcheon. "Repeated replacement of an intrabacterial symbiont in the tripartite nested mealybug symbiosis." Proceedings of the National Academy of Sciences 113, no. 37 (August 29, 2016): E5416—E5424. http://dx.doi.org/10.1073/pnas.1603910113.
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Stable endosymbiosis of a bacterium into a host cell promotes cellular and genomic complexity. The mealybugPlanococcus citrihas two bacterial endosymbionts with an unusual nested arrangement: the γ-proteobacteriumMoranella endobialives in the cytoplasm of the β-proteobacteriumTremblaya princeps. These two bacteria, along with genes horizontally transferred from other bacteria to theP. citrigenome, encode gene sets that form an interdependent metabolic patchwork. Here, we test the stability of this three-way symbiosis by sequencing host and symbiont genomes for five diverse mealybug species and find marked fluidity over evolutionary time. AlthoughTremblayais the result of a single infection in the ancestor of mealybugs, the γ-proteobacterial symbionts result from multiple replacements of inferred different ages from related but distinct bacterial lineages. Our data show that symbiont replacement can happen even in the most intricate symbiotic arrangements and that preexisting horizontally transferred genes can remain stable on genomes in the face of extensive symbiont turnover.
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Chepkemoi, Sharon T., Enock Mararo, Hellen Butungi, Juan Paredes, Daniel K. Masiga, Steven P. Sinkins, and Jeremy K. Herren. "Identification of Spiroplasma insolitum symbionts in Anopheles gambiae." Wellcome Open Research 2 (September 26, 2017): 90. http://dx.doi.org/10.12688/wellcomeopenres.12468.1.
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Background: Insect symbionts have the potential to block the transmission of vector-borne diseases by their hosts. The advancement of a symbiont-based transmission blocking strategy for malaria requires the identification and study of Anopheles symbionts. Methods: High throughput 16S amplicon sequencing was used to profile the bacteria associated with Anopheles gambiae sensu lato and identify potential symbionts. The polymerase chain reaction (PCR) with specific primers were subsequently used to monitor symbiont prevalence in field populations, as well as symbiont transmission patterns. Results: We report the discovery of the bacterial symbiont, Spiroplasma, in Anopheles gambiae in Kenya. We determine that geographically dispersed Anopheles gambiae populations in Kenya are infected with Spiroplasma at low prevalence levels. Molecular phylogenetics indicates that this Anopheles gambiae associated Spiroplasma is a member of the insolitum clade. We demonstrate that this symbiont is stably maternally transmitted across at least two generations and does not significantly affect the fecundity or egg to adult survival of its host. Conclusions: In diverse insect species, Spiroplasma has been found to render their host resistant to infection by pathogens. The identification of a maternally transmitted strain of Spiroplasma in Anopheles gambiae may therefore open new lines of investigation for the development of symbiont-based strategies for blocking malaria transmission.
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Laughton, Alice M., Maretta H. Fan, and Nicole M. Gerardo. "The Combined Effects of Bacterial Symbionts and Aging on Life History Traits in the Pea Aphid, Acyrthosiphon pisum." Applied and Environmental Microbiology 80, no. 2 (November 1, 2013): 470–77. http://dx.doi.org/10.1128/aem.02657-13.
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ABSTRACTWhile many endosymbionts have beneficial effects on hosts under specific ecological conditions, there can also be associated costs. In order to maximize their own fitness, hosts must facilitate symbiont persistence while preventing symbiont exploitation of resources, which may require tight regulation of symbiont populations. As a host ages, the ability to invest in such mechanisms may lessen or be traded off with demands of other life history traits, such as survival and reproduction. Using the pea aphid,Acyrthosiphon pisum, we measured survival, lifetime fecundity, and immune cell counts (hemocytes, a measure of immune capacity) in the presence of facultative secondary symbionts. Additionally, we quantified the densities of the obligate primary bacterial symbiont,Buchnera aphidicola, and secondary symbionts across the host's lifetime. We found life history costs to harboring some secondary symbiont species. Secondary symbiont populations were found to increase with host age, whileBuchnerapopulations exhibited a more complicated pattern. Immune cell counts peaked at the midreproductive stage before declining in the oldest aphids. The combined effects of immunosenescence and symbiont population growth may have important consequences for symbiont transmission and maintenance within a host population.
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Kashkouli, Marzieh, Yaghoub Fathipour, and Mohammad Mehrabadi. "Heritable Gammaproteobacterial Symbiont Improves the Fitness of Brachynema germari Kolenati (Hemiptera: Pentatomidae)." Environmental Entomology 48, no. 5 (July 30, 2019): 1079–87. http://dx.doi.org/10.1093/ee/nvz089.
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Abstract The pistachio green stink bug, Brachynema germari Kolenati, is an abundant and economic insect pest in most pistachio-growing regions. Some physiological and ecological features of this pest have been studied, but the microbiological nature of symbiotic bacteria and biological aspects of this host–symbiont interaction have been poorly understood. In the present study, we explored the host-associated environment, phylogeny, and acquisition features of the bacterial symbiont of the insect. Furthermore, the importance of the symbiont on the biological (i.e., lifespan, stage composition, and body weight) and behavioral characteristics (i.e., resting/wandering behaviors of the newborn nymphs) of the host were investigated. We found that a rod-shaped gammaproteobacterium was persistently colonized the fourth midgut region of the insect. Molecular phylogenetic and fluorescence in situ hybridization analyses strongly suggest that this symbiont should be placed in the genus Pantoea of the Enterobacteriales. Egg surface sterilization resulted in the aposymbiotic insects suggesting the vertical transmission of symbiont via egg surface smearing upon oviposition. Symbiotic and aposymbiotic B. germari showed no significant differences in the wandering behaviors of the first nymphal stages, whereas the symbiont-free insects exhibited retarded growth, lower longevity, and adult body weight. Taken together, these data provide a better understanding of the relationship between the bacterial symbiont and B. germari and demonstrate that the insect is heavily affected by the deprival of its gut symbionts.
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Zchori-Fein, Einat, Steve J. Perlman, Suzanne E. Kelly, Nurit Katzir, and Martha S. Hunter. "Characterization of a ‘Bacteroidetes’ symbiont in Encarsia wasps (Hymenoptera: Aphelinidae): proposal of ‘Candidatus Cardinium hertigii’." International Journal of Systematic and Evolutionary Microbiology 54, no. 3 (May 1, 2004): 961–68. http://dx.doi.org/10.1099/ijs.0.02957-0.
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Previously, analysis of 16S rDNA sequences placed a newly discovered lineage of bacterial symbionts of arthropods in the ‘Bacteroidetes’. This symbiont lineage is associated with a number of diverse host reproductive manipulations, including induction of parthenogenesis in several Encarsia parasitoid wasps (Hymenoptera: Aphelinidae). In this study, electron microscopy and phylogenetic analysis of the 16S rRNA and gyrB genes of symbionts from Encarsia hispida and Encarsia pergandiella are used to describe and further characterize these bacteria. Phylogenetic analyses based on these two genes showed that the Encarsia symbionts are allied with the Cytophaga aurantiaca lineage within the ‘Bacteroidetes’, with their closest described relative being the acanthamoeba symbiont ‘Candidatus Amoebophilus asiaticus’. The Encarsia symbionts share 97 % 16S rDNA sequence similarity with Brevipalpus mite and Ixodes tick symbionts and 88 % sequence similarity with ‘Candidatus A. asiaticus’. Electron microscopy revealed that many of the bacteria found in the ovaries of the two Encarsia species contained a regular, brush-like array of microfilament-like structures that appear to be characteristic of the symbiont. Finally, the role of this bacterium in parthenogenesis induction in E. hispida was confirmed. Based on phylogenetic analyses and electron microscopy, classification of the symbionts from Encarsia as ‘Candidatus Cardinium hertigii’ is proposed.
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Lim-Fong, Grace E., Lindsay A. Regali, and Margo G. Haygood. "Evolutionary Relationships of “Candidatus Endobugula” Bacterial Symbionts and Their Bugula Bryozoan Hosts." Applied and Environmental Microbiology 74, no. 11 (April 4, 2008): 3605–9. http://dx.doi.org/10.1128/aem.02798-07.
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ABSTRACT Ribosomal gene sequences were obtained from bryozoans in the genus Bugula and their bacterial symbionts; analyses of host and symbiont phylogenetic trees did not support a history of strict cospeciation. Symbiont-derived compounds known to defend host larvae from predation were only detected in two out of four symbiotic Bugula species.
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Mao, Meng, Xiushuai Yang, and Gordon M. Bennett. "Evolution of host support for two ancient bacterial symbionts with differentially degraded genomes in a leafhopper host." Proceedings of the National Academy of Sciences 115, no. 50 (November 21, 2018): E11691—E11700. http://dx.doi.org/10.1073/pnas.1811932115.
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Plant sap-feeding insects (Hemiptera) rely on bacterial symbionts for nutrition absent in their diets. These bacteria experience extreme genome reduction and require genetic resources from their hosts, particularly for basic cellular processes other than nutrition synthesis. The host-derived mechanisms that complete these processes have remained poorly understood. It is also unclear how hosts meet the distinct needs of multiple bacterial partners with differentially degraded genomes. To address these questions, we investigated the cell-specific gene-expression patterns in the symbiotic organs of the aster leafhopper (ALF), Macrosteles quadrilineatus (Cicadellidae). ALF harbors two intracellular symbionts that have two of the smallest known bacterial genomes: Nasuia (112 kb) and Sulcia (190 kb). Symbionts are segregated into distinct host cell types (bacteriocytes) and vary widely in their basic cellular capabilities. ALF differentially expresses thousands of genes between the bacteriocyte types to meet the functional needs of each symbiont, including the provisioning of metabolites and support of cellular processes. For example, the host highly expresses genes in the bacteriocytes that likely complement gene losses in nucleic acid synthesis, DNA repair mechanisms, transcription, and translation. Such genes are required to function in the bacterial cytosol. Many host genes comprising these support mechanisms are derived from the evolution of novel functional traits via horizontally transferred genes, reassigned mitochondrial support genes, and gene duplications with bacteriocyte-specific expression. Comparison across other hemipteran lineages reveals that hosts generally support the incomplete symbiont cellular processes, but the origins of these support mechanisms are generally specific to the host–symbiont system.
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Abfa, Iqna Kamila, Ocky Karna Radjasa, A. B. Susanto, Handung Nuryadi, and Ferry F. Karwur. "Exploration, Isolation, and Identification of Carotenoid from Bacterial Symbiont of Sponge Callyspongia vaginalis." ILMU KELAUTAN: Indonesian Journal of Marine Sciences 22, no. 2 (June 6, 2017): 49–58. http://dx.doi.org/10.14710/ik.ijms.22.2.49-58.
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During the past two decades research on marine bacteria has highlighted the tremendous potential of symbiotic-microorganisms as a source of bioactive secondary. One of the potential of the bacterial symbionts is producing a natural pigment, and these organisms can be used as a sustainable source of natural pigments. Carotenoid is one of the most important pigments that has important roles in physiological and molecular processes of microorganisms, as well as for human health. The objective of this study is to analyze carotenoid pigments from marine bacterial symbionts from sponge and to identify bacterial symbionts that produce carotenoid pigments. Pigment analysis was performed by a UV-VIS spectrophotometer and High Performance Liquid Chromatography (HPLC). Molecular bacterial identification was performed based on 16S rDNA sequence. The isolation of bacterial symbionts from C. vaginalison Zobell 2216E medium resulted in one bacterium, CB-SP5, positively synthesized carotenoids. By reverse phase HPLC analysis, the carotenoid pigments in the bacterial symbionts were identified as diadinoxanthin, fucoxanthin, neoxanthin, dinoxanthin, anddiadinochrome. CB-SP5 shared the highest level of 16S rDNA gene sequence similarity with Psychrobacter celer (99%). Keywords : carotenoid, sponge, bacterial symbiont, 16S rDNA.
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Matsuura, Yu, Minoru Moriyama, Piotr Łukasik, Dan Vanderpool, Masahiko Tanahashi, Xian-Ying Meng, John P. McCutcheon, and Takema Fukatsu. "Recurrent symbiont recruitment from fungal parasites in cicadas." Proceedings of the National Academy of Sciences 115, no. 26 (June 11, 2018): E5970—E5979. http://dx.doi.org/10.1073/pnas.1803245115.
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Diverse insects are associated with ancient bacterial symbionts, whose genomes have often suffered drastic reduction and degeneration. In extreme cases, such symbiont genomes seem almost unable to sustain the basic cellular functioning, which comprises an open question in the evolution of symbiosis. Here, we report an insect group wherein an ancient symbiont lineage suffering massive genome erosion has experienced recurrent extinction and replacement by host-associated pathogenic microbes. Cicadas are associated with the ancient bacterial co-obligate symbiontsSulciaandHodgkinia, whose streamlined genomes are specialized for synthesizing essential amino acids, thereby enabling the host to live on plant sap. However, our inspection of 24 Japanese cicada species revealed that while all species possessedSulcia, only nine species retainedHodgkinia, and their genomes exhibited substantial structural instability. The remaining 15 species lackedHodgkiniaand instead harbored yeast-like fungal symbionts. Detailed phylogenetic analyses uncovered repeatedHodgkinia-fungus and fungus-fungus replacements in cicadas. The fungal symbionts were phylogenetically intermingled with cicada-parasitizingOphiocordycepsfungi, identifying entomopathogenic origins of the fungal symbionts. Most fungal symbionts of cicadas were uncultivable, but the fungal symbiont ofMeimuna opaliferawas cultivable, possibly because it is at an early stage of fungal symbiont replacement. Genome sequencing of the fungal symbiont revealed its metabolic versatility, presumably capable of synthesizing almost all amino acids, vitamins, and other metabolites, which is more than sufficient to compensate for theHodgkinialoss. These findings highlight a straightforward ecological and evolutionary connection between parasitism and symbiosis, which may provide an evolutionary trajectory to renovate deteriorated ancient symbiosis via pathogen domestication.
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Majeed, Muhammad Zeeshan, Samy Sayed, Zhang Bo, Ahmed Raza, and Chun-Sen Ma. "Bacterial Symbionts Confer Thermal Tolerance to Cereal Aphids Rhopalosiphum padi and Sitobion avenae." Insects 13, no. 3 (February 25, 2022): 231. http://dx.doi.org/10.3390/insects13030231.
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High-temperature events are evidenced to exert significant influence on the population performance and thermal biology of insects, such as aphids. However, it is not yet clear whether the bacterial symbionts of insects mediate the thermal tolerance traits of their hosts. This study is intended to assess the putative association among the chronic and acute thermal tolerance of two cereal aphid species, Rhopalosiphum padi (L.) and Sitobion avenae (F.), and the abundance of their bacterial symbionts. The clones of aphids were collected randomly from different fields of wheat crops and were maintained under laboratory conditions. Basal and acclimated CTmax and chronic thermal tolerance indices were measured for 5-day-old apterous aphid individuals and the abundance (gene copy numbers) of aphid-specific and total (16S rRNA) bacterial symbionts were determined using real-time RT-qPCR. The results reveal that R. padi individuals were more temperature tolerant under chronic exposure to 31 °C and also exhibited about 1.0 °C higher acclimated and basal CTmax values than those of S. avenae. Moreover, a significantly higher bacterial symbionts’ gene abundance was recorded in temperature-tolerant aphid individuals than the susceptible ones for both aphid species. Although total bacterial (16S rRNA) abundance per aphid was higher in S. avenae than R. padi, the gene abundance of aphid-specific bacterial symbionts was nearly alike for both of the aphid species. Nevertheless, basal and acclimated CTmax values were positively and significantly associated with the gene abundance of total symbiont density, Buchnera aphidicola, Serratia symbiotica, Hamilton defensa, Regiella insecticola and Spiroplasma spp. for R. padi, and with the total symbiont density, total bacteria (16S rRNA) and with all aphid-specific bacterial symbionts (except Spiroplasma spp.) for S. avenae. The overall study results corroborate the potential role of the bacterial symbionts of aphids in conferring thermal tolerance to their hosts.
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Salem, Hassan, and Martin Kaltenpoth. "Beetle–Bacterial Symbioses: Endless Forms Most Functional." Annual Review of Entomology 67, no. 1 (January 7, 2022): 201–19. http://dx.doi.org/10.1146/annurev-ento-061421-063433.
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Beetles are hosts to a remarkable diversity of bacterial symbionts. In this article, we review the role of these partnerships in promoting beetle fitness following a surge of recent studies characterizing symbiont localization and function across the Coleoptera. Symbiont contributions range from the supplementation of essential nutrients and digestive or detoxifying enzymes to the production of bioactive compounds providing defense against natural enemies. Insights on this functional diversity highlight how symbiosis can expand the host's ecological niche, but also constrain its evolutionary potential by promoting specialization. As bacterial localization can differ within and between beetle clades, we discuss how it corresponds to the microbe's beneficial role and outline the molecular and behavioral mechanisms underlying symbiont translocation and transmission by its holometabolous host. In reviewing this literature, we emphasize how the study of symbiosis can inform our understanding of the phenotypic innovations behind the evolutionary success of beetles.
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Boyd, Bret M., Julie M. Allen, Ryuichi Koga, Takema Fukatsu, Andrew D. Sweet, Kevin P. Johnson, and David L. Reed. "Two Bacterial Genera, Sodalis and Rickettsia, Associated with the Seal Louse Proechinophthirus fluctus (Phthiraptera: Anoplura)." Applied and Environmental Microbiology 82, no. 11 (March 18, 2016): 3185–97. http://dx.doi.org/10.1128/aem.00282-16.
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ABSTRACTRoughly 10% to 15% of insect species host heritable symbiotic bacteria known as endosymbionts. The lice parasitizing mammals rely on endosymbionts to provide essential vitamins absent in their blood meals. Here, we describe two bacterial associates from a louse,Proechinophthirus fluctus, which is an obligate ectoparasite of a marine mammal. One of these is a heritable endosymbiont that is not closely related to endosymbionts of other mammalian lice. Rather, it is more closely related to endosymbionts of the genusSodalisassociated with spittlebugs and feather-chewing bird lice. Localization and vertical transmission of this endosymbiont are also more similar to those of bird lice than to those of other mammalian lice. The endosymbiont genome appears to be degrading in symbiosis; however, it is considerably larger than the genomes of other mammalian louse endosymbionts. These patterns suggest the possibility that thisSodalisendosymbiont might be recently acquired, replacing a now-extinct, ancient endosymbiont. From the same lice, we also identified an abundant bacterium belonging to the genusRickettsiathat is closely related toRickettsia ricketsii, a human pathogen vectored by ticks. No obvious masses of theRickettsiabacterium were observed in louse tissues, nor did we find any evidence of vertical transmission, so the nature of its association remains unclear.IMPORTANCEMany insects are host to heritable symbiotic bacteria. These heritable bacteria have been identified from numerous species of parasitic lice. It appears that novel symbioses have formed between lice and bacteria many times, with new bacterial symbionts potentially replacing existing ones. However, little was known about the symbionts of lice parasitizing marine mammals. Here, we identified a heritable bacterial symbiont in lice parasitizing northern fur seals. This bacterial symbiont appears to have been recently acquired by the lice. The findings reported here provide insights into how new symbioses form and how this lifestyle is shaping the symbiont genome.
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Palmer-Young, Evan C., Thomas R. Raffel, and Quinn S. McFrederick. "Temperature-mediated inhibition of a bumblebee parasite by an intestinal symbiont." Proceedings of the Royal Society B: Biological Sciences 285, no. 1890 (October 31, 2018): 20182041. http://dx.doi.org/10.1098/rspb.2018.2041.
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Competition between organisms is often mediated by environmental factors, including temperature. In animal intestines, nonpathogenic symbionts compete physically and chemically against pathogens, with consequences for host infection. We used metabolic theory-based models to characterize differential responses to temperature of a bacterial symbiont and a co-occurring trypanosomatid parasite of bumblebees, which regulate body temperature during flight and incubation. We hypothesized that inhibition of parasites by bacterial symbionts would increase with temperature, due to symbionts having higher optimal growth temperatures than parasites. We found that a temperature increase over the range measured in bumblebee colonies would favour symbionts over parasites. As predicted by our hypothesis, symbionts reduced the optimal growth temperature for parasites, both in direct competition and when parasites were exposed to symbiont spent medium. Inhibitory effects of the symbiont increased with temperature, reflecting accelerated growth and acid production by symbionts. Our results indicate that high temperatures, whether due to host endothermy or environmental factors, can enhance the inhibitory effects of symbionts on parasites. Temperature-modulated manipulation of microbiota could be one explanation for fever- and heat-induced reductions of infection in animals, with consequences for diseases of medical and conservation concern.
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Russell, S. L., E. McCartney, and C. M. Cavanaugh. "Transmission strategies in a chemosynthetic symbiosis: detection and quantification of symbionts in host tissues and their environment." Proceedings of the Royal Society B: Biological Sciences 285, no. 1890 (October 31, 2018): 20182157. http://dx.doi.org/10.1098/rspb.2018.2157.
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Transmission of bacteria vertically through host tissues ensures offspring acquire symbionts; however, horizontal transmission is an effective strategy for many associations and plays a role in some vertically transmitted symbioses. The bivalve Solemya velum and its gammaproteobacterial chemosynthetic symbionts exhibit evolutionary evidence of both transmission modes, but the dominant strategy on an ecological time scale is unknown. To address this, a specific primer set was developed and validated for the S. velum symbiont using a novel workflow called specific marker design (SMD). Symbionts were quantified in spawned eggs and sediment and seawater samples from S. velum habitats with qPCR. Each egg was estimated to contain 50–100 symbiont genomes. By contrast, symbiont DNA was found at low abundance/occurrence in sediment and seawater, often co-occurring with host mitochondrial DNA, obscuring its origin. To ascertain when eggs become infected, histological sections of S. velum tissues were labelled for symbiont 16S rRNA via in situ hybridization. This revealed symbionts in the ovary walls and mature oocytes, suggesting association in late oogenesis. These data support the hypothesis that S. velum symbionts are vertically transmitted every host generation, thus genetic signatures of horizontal transmission are driven by ecologically infrequent events. This knowledge furthers our understanding of vertical and horizontal mode integration and provides insights across animal–bacterial chemosynthetic symbioses.
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Fukatsu, Takema, Ryuichi Koga, Wendy A. Smith, Kohjiiro Tanaka, Naruo Nikoh, Kayoko Sasaki-Fukatsu, Kazunori Yoshizawa, Colin Dale, and Dale H. Clayton. "Bacterial Endosymbiont of the Slender Pigeon Louse, Columbicola columbae, Allied to Endosymbionts of Grain Weevils and Tsetse Flies." Applied and Environmental Microbiology 73, no. 20 (August 31, 2007): 6660–68. http://dx.doi.org/10.1128/aem.01131-07.
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ABSTRACT The current study focuses on a symbiotic bacterium found in the slender pigeon louse, Columbicola columbae (Insecta: Phthiraptera). Molecular phylogenetic analyses indicated that the symbiont belongs to the gamma subdivision of the class Proteobacteria and is allied to Sodalis glossinidius, the secondary symbiont of tsetse flies (Glossina spp.) and also to the primary symbiont of grain weevils (Sitophilus spp.). Relative-rate tests revealed that the symbiont of C. columbae exhibits accelerated molecular evolution in comparison with the tsetse fly symbiont and the weevil symbiont. Whole-mount in situ hybridization was used to localize the symbiont and determine infection dynamics during host development. In first- and second-instar nymphs, the symbionts were localized in the cytoplasm of oval bacteriocytes that formed small aggregates on both sides of the body cavity. In third-instar nymphs, the bacteriocytes migrated to the central body and were finally located in the anterior region of the lateral oviducts, forming conspicuous tissue formations called ovarial ampullae. In adult females, the symbionts were transmitted from the ovarial ampullae to developing oocytes in the ovarioles. In adult males, the bacteriocytes often disappeared without migration. A diagnostic PCR survey of insects collected from Japan, the United States, Australia, and Argentina detected 96.5% (109/113) infection, with a few uninfected male insects. This study provides the first microbial characterization of a bacteriocyte-associated symbiont from a chewing louse. Possible biological roles of the symbiont are discussed in relation to the host nutritional physiology associated with the feather-feeding lifestyle.
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Jäckle, Oliver, Brandon K. B. Seah, Målin Tietjen, Nikolaus Leisch, Manuel Liebeke, Manuel Kleiner, Jasmine S. Berg, and Harald R. Gruber-Vodicka. "Chemosynthetic symbiont with a drastically reduced genome serves as primary energy storage in the marine flatwormParacatenula." Proceedings of the National Academy of Sciences 116, no. 17 (April 8, 2019): 8505–14. http://dx.doi.org/10.1073/pnas.1818995116.
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Hosts of chemoautotrophic bacteria typically have much higher biomass than their symbionts and consume symbiont cells for nutrition. In contrast to this, chemoautotrophicCandidatusRiegeria symbionts in mouthlessParacatenulaflatworms comprise up to half of the biomass of the consortium. Each species ofParacatenulaharbors a specificCa. Riegeria, and the endosymbionts have been vertically transmitted for at least 500 million years. Such prolonged strict vertical transmission leads to streamlining of symbiont genomes, and the retained physiological capacities reveal the functions the symbionts provide to their hosts. Here, we studied a species ofParacatenulafrom Sant’Andrea, Elba, Italy, using genomics, gene expression, imaging analyses, as well as targeted and untargeted MS. We show that its symbiont,Ca. R. santandreae has a drastically smaller genome (1.34 Mb) than the symbiont´s free-living relatives (4.29–4.97 Mb) but retains a versatile and energy-efficient metabolism. It encodes and expresses a complete intermediary carbon metabolism and enhanced carbon fixation through anaplerosis and accumulates massive intracellular inclusions such as sulfur, polyhydroxyalkanoates, and carbohydrates. Compared with symbiotic and free-living chemoautotrophs,Ca. R. santandreae’s versatility in energy storage is unparalleled in chemoautotrophs with such compact genomes. Transmission EM as well as host and symbiont expression data suggest thatCa. R. santandreae largely provisions its host via outer-membrane vesicle secretion. With its high share of biomass in the symbiosis and large standing stocks of carbon and energy reserves, it has a unique role for bacterial symbionts—serving as the primary energy storage for its animal host.
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Ferrari, Julia, and Fabrice Vavre. "Bacterial symbionts in insects or the story of communities affecting communities." Philosophical Transactions of the Royal Society B: Biological Sciences 366, no. 1569 (May 12, 2011): 1389–400. http://dx.doi.org/10.1098/rstb.2010.0226.
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Bacterial symbionts are widespread in insects and other animals. Most of them are predominantly vertically transmitted, along with their hosts' genes, and thus extend the heritable genetic variation present in one species. These passengers have a variety of repercussions on the host's phenotypes: besides the cost imposed on the host for maintaining the symbiont population, they can provide fitness advantages to the host or manipulate the host's reproduction. We argue that insect symbioses are ideal model systems for community genetics. First, bacterial symbionts directly or indirectly affect the interactions with other species within a community. Examples include their involvement in modifying the use of host plants by phytophagous insects, in providing resistance to natural enemies, but also in reducing the global genetic diversity or gene flow between populations within some species. Second, one emerging picture in insect symbioses is that many species are simultaneously infected with more than one symbiont, which permits studying the factors that shape bacterial communities; for example, horizontal transmission, interactions between host genotype, symbiont genotype and the environment and interactions among symbionts. One conclusion is that insects' symbiotic complements are dynamic communities that affect and are affected by the communities in which they are embedded.
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Millikan, Deborah S., Horst Felbeck, and Jeffrey L. Stein. "Identification and Characterization of a Flagellin Gene from the Endosymbiont of the Hydrothermal Vent TubewormRiftia pachyptila." Applied and Environmental Microbiology 65, no. 7 (July 1, 1999): 3129–33. http://dx.doi.org/10.1128/aem.65.7.3129-3133.1999.
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ABSTRACT The bacterial endosymbionts of the hydrothermal vent tubewormRiftia pachyptila play a key role in providing their host with fixed carbon. Results of prior research suggest that the symbionts are selected from an environmental bacterial population, although a free-living form has been neither cultured from nor identified in the hydrothermal vent environment. To begin to assess the free-living potential of the symbiont, we cloned and characterized a flagellin gene from a symbiont fosmid library. The symbiont fliC gene has a high degree of homology with other bacterial flagellin genes in the amino- and carboxy-terminal regions, while the central region was found to be nonconserved. A sequence that was homologous to that of a consensus ς28 RNA polymerase recognition site lay upstream of the proposed translational start site. The symbiont protein was expressed in Escherichia coli, and flagella were observed by electron microscopy. A 30,000-M rprotein subunit was identified in whole-cell extracts by Western blot analysis. These results provide the first direct evidence of a motile free-living stage of a chemoautotrophic symbiont and support the hypothesis that the symbiont of R. pachyptila is acquired with each new host generation.
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GREWAL, P. S., M. MATSUURA, and V. CONVERSE. "Mechanisms of specificity of association between the nematode Steinernema scapterisci and its symbiotic bacterium." Parasitology 114, no. 5 (May 1997): 483–88. http://dx.doi.org/10.1017/s0031182096008669.
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We suggest a new mechanism for the maintenance of specificity of the association between the entomopathogenic nematode Steinernema scapterisci and its symbiotic bacteria. We evaluated the development and reproduction of infective and non-infective juvenile S. scapterisci in monoxenic combinations with its symbiotic bacteria, Xenorhabdus sp. ‘S’ and with the bacterial symbiont of Steinernema carpocapsae and Steinernema riobravis. Although development of non-infective stages occurred on all Xenorhabdus spp., the development of infective juveniles to the 4th stage (‘dauer’ recovery) was significantly delayed and reduced with X. nematophilus and Xenorhabdus sp. ‘R’, the bacterial symbionts of S. carpocapsae and S. riobravis, respectively. ‘Dauer’ recovery improved significantly when the cultures of X. nematophilus and Xenorhabdus sp. ‘R’ were supplemented with cell-free filtrates from Xenorhabdus sp. ‘S’. The infective juvenile S. scapterisci produced in all 3 cultures were virulent to Galleria mellonella larvae, confirming successful retention of Xenorhabdus from other steinernematids in their intestine. In fact, S. scapterisci infective juveniles containing X. nematophilus or Xenorhabdus sp. ‘R’ were more virulent to G. mellonella than those containing their natural symbiont, Xenorhabdus sp. ‘S’. We believe that this is the first demonstration of the symbiont-specific exit of infective juveniles from the ‘dauer’ phase which represents the finest level of specificity of bacteria–nematode association. This is also the first report of successful isolation of the natural symbiont of S. scapterisci.
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Davidson, S. K., S. W. Allen, G. E. Lim, C. M. Anderson, and M. G. Haygood. "Evidence for the Biosynthesis of Bryostatins by the Bacterial Symbiont “Candidatus Endobugula sertula” of the BryozoanBugula neritina." Applied and Environmental Microbiology 67, no. 10 (October 1, 2001): 4531–37. http://dx.doi.org/10.1128/aem.67.10.4531-4537.2001.
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ABSTRACT The marine bryozoan, Bugula neritina, is the source of the bryostatins, a family of macrocyclic lactones with anticancer activity. Bryostatins have long been suspected to be bacterial products. B. neritina harbors the uncultivated gamma proteobacterial symbiont “Candidatus Endobugula sertula.” In this work several lines of evidence are presented that show that the symbiont is the most likely source of bryostatins. Bryostatins are complex polyketides similar to bacterial secondary metabolites synthesized by modular type I polyketide synthases (PKS-I). PKS-I gene fragments were cloned from DNA extracted from the B. neritina-“E. sertula”association, and then primers specific to one of these clones, KSa, were shown to amplify the KSa gene specifically and universally from total B. neritina DNA. In addition, a KSa RNA probe was shown to bind specifically to the symbiotic bacteria located in the pallial sinus of the larvae of B. neritina and not to B. neritina cells or to other bacteria. Finally,B. neritina colonies grown in the laboratory were treated with antibiotics to reduce the numbers of bacterial symbionts. Decreased symbiont levels resulted in the reduction of the KSa signal as well as the bryostatin content. These data provide evidence that the symbiont E. sertula has the genetic potential to make bryostatins and is necessary in full complement for the host bryozoan to produce normal levels of bryostatins. This study demonstrates that it may be possible to clone bryostatin genes from B. neritina directly and use these to produce bryostatins in heterologous host bacteria.
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Renoz, François, Jérôme Ambroise, Bertrand Bearzatto, Samir Fakhour, Nicolas Parisot, Mélanie Ribeiro Lopes, Jean-Luc Gala, Federica Calevro, and Thierry Hance. "The Di-Symbiotic Systems in the Aphids Sipha maydis and Periphyllus lyropictus Provide a Contrasting Picture of Recent Co-Obligate Nutritional Endosymbiosis in Aphids." Microorganisms 10, no. 7 (July 6, 2022): 1360. http://dx.doi.org/10.3390/microorganisms10071360.
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Dependence on multiple nutritional bacterial symbionts forming a metabolic unit has repeatedly evolved in many insect species that feed on nutritionally unbalanced diets such as plant sap. This is the case for aphids of the subfamilies Lachninae and Chaitophorinae, which have evolved di-symbiotic systems in which the ancient obligate nutritional symbiont Buchnera aphidicola is metabolically complemented by an additional nutritional symbiont acquired more recently. Deciphering how different symbionts integrate both metabolically and anatomically in such systems is crucial to understanding how complex nutritional symbiotic systems function and evolve. In this study, we sequenced and analyzed the genomes of the symbionts B. aphidicola and Serratia symbiotica associated with the Chaitophorinae aphids Sipha maydis and Periphyllus lyropictus. Our results show that, in these two species, B. aphidicola and S. symbiotica complement each other metabolically (and their hosts) for the biosynthesis of essential amino acids and vitamins, but with distinct metabolic reactions supported by each symbiont depending on the host species. Furthermore, the S. symbiotica symbiont associated with S. maydis appears to be strictly compartmentalized into the specialized host cells housing symbionts in aphids, the bacteriocytes, whereas the S. symbiotica symbiont associated with P. lyropictus exhibits a highly invasive phenotype, presumably because it is capable of expressing a larger set of virulence factors, including a complete flagellum for bacterial motility. Such contrasting levels of metabolic and anatomical integration for two S. symbiotica symbionts that were recently acquired as nutritional co-obligate partners reflect distinct coevolutionary processes specific to each association.
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Bulgheresi, Silvia, Irma Schabussova, Tie Chen, Nicholas P. Mullin, Rick M. Maizels, and Jörg A. Ott. "A New C-Type Lectin Similar to the Human Immunoreceptor DC-SIGN Mediates Symbiont Acquisition by a Marine Nematode." Applied and Environmental Microbiology 72, no. 4 (April 2006): 2950–56. http://dx.doi.org/10.1128/aem.72.4.2950-2956.2006.
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ABSTRACT Although thiotrophic symbioses have been intensively studied for the last three decades, nothing is known about the molecular mechanisms of symbiont acquisition. We used the symbiosis between the marine nematode Laxus oneistus and sulfur-oxidizing bacteria to study this process. In this association a monolayer of symbionts covers the whole cuticle of the nematode, except its anterior-most region. Here, we identify a novel Ca2+-dependent mannose-specific lectin that was exclusively secreted onto the posterior, bacterium-associated region of L. oneistus cuticle. A recombinant form of this lectin induced symbiont aggregation in seawater and was able to compete with the native lectin for symbiont binding in vivo. Surprisingly, the carbohydrate recognition domain of this mannose-binding protein was similar both structurally and functionally to a human dendritic cell-specific immunoreceptor. Our results provide a molecular link between bacterial symbionts and host-secreted mucus in a marine symbiosis and suggest conservation in the mechanisms of host-microbe interactions throughout the animal kingdom.
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Lorion, Julien, Sébastien Duperron, Olivier Gros, Corinne Cruaud, and Sarah Samadi. "Several deep-sea mussels and their associated symbionts are able to live both on wood and on whale falls." Proceedings of the Royal Society B: Biological Sciences 276, no. 1654 (September 16, 2008): 177–85. http://dx.doi.org/10.1098/rspb.2008.1101.
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Bathymodiolin mussels occur at hydrothermal vents and cold seeps, where they thrive thanks to symbiotic associations with chemotrophic bacteria. Closely related genera Idas and Adipicola are associated with organic falls, ecosystems that have been suggested as potential evolutionary ‘stepping stones’ in the colonization of deeper and more sulphide-rich environments. Such a scenario should result from specializations to given environments from species with larger ecological niches. This study provides molecular-based evidence for the existence of two mussel species found both on sunken wood and bones. Each species specifically harbours one bacterial phylotype corresponding to thioautotrophic bacteria related to other bathymodiolin symbionts. Phylogenetic patterns between hosts and symbionts are partially congruent. However, active endocytosis and occurrences of minor symbiont lineages within species which are not their usual host suggest an environmental or horizontal rather than strictly vertical transmission of symbionts. Although the bacteria are close relatives, their localization is intracellular in one mussel species and extracellular in the other, suggesting that habitat choice is independent of the symbiont localization. The variation of bacterial densities in host tissues is related to the substrate on which specimens were sampled and could explain the abilities of host species to adapt to various substrates.
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Hurtado, Luis A., Mariana Mateos, Richard A. Lutz, and Robert C. Vrijenhoek. "Coupling of Bacterial Endosymbiont and Host Mitochondrial Genomes in the Hydrothermal Vent Clam Calyptogena magnifica." Applied and Environmental Microbiology 69, no. 4 (April 2003): 2058–64. http://dx.doi.org/10.1128/aem.69.4.2058-2064.2003.
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ABSTRACT The hydrothermal vent clam Calyptogena magnifica (Bivalvia: Vesicomyidae) depends for its nutrition on sulfur-oxidizing symbiotic bacteria housed in its gill tissues. This symbiont is transmitted vertically between generations via the clam's eggs; however, it remains uncertain whether occasionally symbionts are horizontally transmitted or acquired from the environment. If symbionts are transmitted strictly vertically through the egg cytoplasm, inheritance of symbiont lineages should behave as if coupled to the host's maternally inherited mitochondrial DNA. This coupling would be obscured, however, with low rates of horizontal or environmental transfers, the equivalent of recombination between host lineages. Population genetic analyses of C. magnifica clams and associated symbionts from eastern Pacific hydrothermal vents clearly supported the hypothesis of strictly maternal cotransmission. Host mitochondrial and symbiont DNA sequences were coupled in a clam population that was polymorphic for both genetic markers. These markers were not similarly coupled with sequence variation at a nuclear gene locus, as expected for a randomly mating sexual population. Phylogenetic analysis of the two cytoplasmic genes also revealed no evidence for recombination. The tight association between vesicomyid clams and their vertically transmitted bacterial endosymbionts is phylogenetically very young (<50 million years) and may serve as a model for the origin and evolution of eukaryotic organelles.
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Ciche, Todd A., Kwi-suk Kim, Bettina Kaufmann-Daszczuk, Ken C. Q. Nguyen, and David H. Hall. "Cell Invasion and Matricide during Photorhabdus luminescens Transmission by Heterorhabditis bacteriophora Nematodes." Applied and Environmental Microbiology 74, no. 8 (February 15, 2008): 2275–87. http://dx.doi.org/10.1128/aem.02646-07.
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ABSTRACT Many animals and plants have symbiotic relationships with beneficial bacteria. Experimentally tractable models are necessary to understand the processes involved in the selective transmission of symbiotic bacteria. One such model is the transmission of the insect-pathogenic bacterial symbionts Photorhabdus spp. by Heterorhabditis bacteriophora infective juvenile (IJ)-stage nematodes. By observing egg-laying behavior and IJ development, it was determined that IJs develop exclusively via intrauterine hatching and matricide (i.e., endotokia matricida). By transiently exposing nematodes to fluorescently labeled symbionts, it was determined that symbionts infect the maternal intestine as a biofilm and then invade and breach the rectal gland epithelium, becoming available to the IJ offspring developing in the pseudocoelom. Cell- and stage-specific infection occurs again in the pre-IJ pharyngeal intestinal valve cells, which helps symbionts to persist as IJs develop and move to a new host. Synchronous with nematode development are changes in symbiont and host behavior (e.g., adherence versus invasion). Thus, Photorhabdus symbionts are maternally transmitted by an elaborate infectious process involving multiple selective steps in order to achieve symbiont-specific transmission.
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Buccella, Constanza, Belinda Alvarez, Karen Gibb, and Anna Padovan. "A rod-like bacterium is responsible for high molybdenum concentrations in the tropical sponge Halichondria phakellioides." Marine and Freshwater Research 65, no. 9 (2014): 838. http://dx.doi.org/10.1071/mf13254.
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The tropical marine sponge, Halichondria phakellioides, from Darwin Harbour contains high concentrations of molybdenum. A rod-like bacterium extracellular in sponge tissue was observed using transmission electron microscopy. Molybdenum was located within these bacteria, but not in sponge cells. This is the first report of the trace element molybdenum localised in a sponge bacterial symbiont. Many different bacterial symbionts were identified in the sponge by sequence analysis so the identity of the molybdenum-accumulating bacterium could only be inferred.
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Osvatic, Jay T., Laetitia G. E. Wilkins, Lukas Leibrecht, Matthieu Leray, Sarah Zauner, Julia Polzin, Yolanda Camacho, et al. "Global biogeography of chemosynthetic symbionts reveals both localized and globally distributed symbiont groups." Proceedings of the National Academy of Sciences 118, no. 29 (July 16, 2021): e2104378118. http://dx.doi.org/10.1073/pnas.2104378118.
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In the ocean, most hosts acquire their symbionts from the environment. Due to the immense spatial scales involved, our understanding of the biogeography of hosts and symbionts in marine systems is patchy, although this knowledge is essential for understanding fundamental aspects of symbiosis such as host–symbiont specificity and evolution. Lucinidae is the most species-rich and widely distributed family of marine bivalves hosting autotrophic bacterial endosymbionts. Previous molecular surveys identified location-specific symbiont types that “promiscuously” form associations with multiple divergent cooccurring host species. This flexibility of host–microbe pairings is thought to underpin their global success, as it allows hosts to form associations with locally adapted symbionts. We used metagenomics to investigate the biodiversity, functional variability, and genetic exchange among the endosymbionts of 12 lucinid host species from across the globe. We report a cosmopolitan symbiont species, Candidatus Thiodiazotropha taylori, associated with multiple lucinid host species. Ca. T. taylori has achieved more success at dispersal and establishing symbioses with lucinids than any other symbiont described thus far. This discovery challenges our understanding of symbiont dispersal and location-specific colonization and suggests both symbiont and host flexibility underpin the ecological and evolutionary success of the lucinid symbiosis.
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Haygood, Margo G., Daniel L. Distel, and Peter J. Herring. "Polymerase Chain reaction and 16S rRNA gene sequences from the luminous bacterial symbionts of two deep-sea anglerfishes." Journal of the Marine Biological Association of the United Kingdom 72, no. 1 (February 1992): 149–59. http://dx.doi.org/10.1017/s0025315400048852.
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Sequences of the 16S ribosomal RNA gene of luminous bacterial symbionts from the escas of the deep sea anglerfishesMelanocetus johnsoniandCryptopsaras couesiwere determined by direct sequencing of polymerase chain reaction products. A sequence was also obtained from a strain ofPhotobacterium phosphoreum, the culturable light organ symbiont ofOpisthoproctus grimaldii. Comparison of these and other published sequences showed that the anglerfish symbionts group with the marine luminous bacteria but are not closely related toP. phosphoreum. The two ceratioid symbionts differ from each other at least at the species level.
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Herrera, Paul, Lisa Schuster, Cecilia Wentrup, Lena König, Thomas Kempinger, Hyunsoo Na, Jasmin Schwarz, et al. "Molecular causes of an evolutionary shift along the parasitism–mutualism continuum in a bacterial symbiont." Proceedings of the National Academy of Sciences 117, no. 35 (August 19, 2020): 21658–66. http://dx.doi.org/10.1073/pnas.2005536117.
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Symbiosis with microbes is a ubiquitous phenomenon with a massive impact on all living organisms, shaping the world around us today. Theoretical and experimental studies show that vertical transmission of symbionts leads to the evolution of mutualistic traits, whereas horizontal transmission facilitates the emergence of parasitic features. However, these studies focused on phenotypic data, and we know little about underlying molecular changes at the genomic level. Here, we combined an experimental evolution approach with infection assays, genome resequencing, and global gene expression analysis to study the effect of transmission mode on an obligate intracellular bacterial symbiont. We show that a dramatic shift in the frequency of genetic variants, coupled with major changes in gene expression, allow the symbiont to alter its position in the parasitism–mutualism continuum depending on the mode of between-host transmission. We found that increased parasitism in horizontally transmitted chlamydiae residing in amoebae was a result of processes occurring at the infectious stage of the symbiont’s developmental cycle. Specifically, genes involved in energy production required for extracellular survival and the type III secretion system—the symbiont’s primary virulence mechanism—were significantly up-regulated. Our results identify the genomic and transcriptional dynamics sufficient to favor parasitic or mutualistic strategies.
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Manzano-Marı́n, Alejandro, Armelle Coeur d’acier, Anne-Laure Clamens, Céline Orvain, Corinne Cruaud, Valérie Barbe, and Emmanuelle Jousselin. "Serial horizontal transfer of vitamin-biosynthetic genes enables the establishment of new nutritional symbionts in aphids’ di-symbiotic systems." ISME Journal 14, no. 1 (October 17, 2019): 259–73. http://dx.doi.org/10.1038/s41396-019-0533-6.
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Abstract 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.
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Burkhart, Craig N., and Craig G. Burkhart. "Bacterial Symbiotes, Their Presence in Head Lice, and Potential Treatment Avenues." Journal of Cutaneous Medicine and Surgery 10, no. 1 (January 2006): 2–6. http://dx.doi.org/10.1007/7140.2006.00003.
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Background: Pediculus humanus capitis (head lice) belongs to the order Anoplura, which are blood-feeding ectoparasites that live on human hair. Within these insects reside symbiotic bacteria that enable the insect to flourish on dietary sources of limited nutritional value. These symbiotic bacteria are essential to the survival of the insect. Objective: To assess the feasibility of treating head lice by altering their symbiotic bacteria. Methods: In addition to a literature review of the expanded role of symbiotic bacteria in other organisms, the anatomic localization of their presence in human head lice and molecular characterization of the head louse symbiont were analyzed. Results: Anatomically, the bacterial symbiotes are localized to the midgut mycetome in males and the ovaries in females. The 16S ribosomal ribonucleic acid phylogenetic analysis was presented. Features of this bacterial symbiote may make this symbiont accessible as a target for pediculocidal and ovicidal therapy by altering its habitat and existence. Conclusions: An understanding of the nature of bacterial symbiotes of head lice might lead to alternative strategies for eradication or inhibition of these necessary bacteria, thereby controlling head lice with less toxic agents than conventional insecticides, to which the organism continues to increase its resistance.
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González, Roxana, Carlos Henríquez-Castillo, Karin B. Lohrmann, María Soledad Romero, Laura Ramajo, Paulina Schmitt, and Katherina Brokordt. "The Gill Microbiota of Argopecten purpuratus Scallop Is Dominated by Symbiotic Campylobacterota and Upwelling Intensification Differentially Affects Their Abundance." Microorganisms 10, no. 12 (November 25, 2022): 2330. http://dx.doi.org/10.3390/microorganisms10122330.
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Despite the great importance of gills for bivalve mollusks (respiration, feeding, immunity), the microbiota associated with this tissue has barely been characterized in scallops. The scallop Argopecten purpuratus is an important economic resource that is cultivated in areas where coastal upwelling is intensifying by climate change, potentially affecting host-microbiota interactions. Thus, we first characterized the bacterial community present in gills from cultivated scallops (by 16S rRNA gene amplicon sequencing) and assessed their stability and functional potential in animals under farm and laboratory conditions. Results showed that under both conditions the gill bacterial community is dominated by the phylum Campylobacterota (57%), which displays a chemoautotrophic potential that could contribute to scallop nutrition. Within this phylum, two phylotypes, namely symbionts A and B, were the most abundant; being, respectively, taxonomically affiliated to symbionts with nutritional functions in mussel gills, and to uncultured bacteria present in coral mucus. Additionally, in situ hybridization and scanning electron microscopy analyses allowed us to detect these symbionts in the gills of A. purpuratus. Given that shifts in upwelling phenology can cause disturbances to ecosystems, affecting bacteria that provide beneficial functions to the host, we further assessed the changes in the abundance of the two symbionts (via qPCR) in response to a simulated upwelling intensification. The exposure to combined decreasing values in the temperature, pH, and oxygen levels (upwelling conditions) favored the dominance of symbiont B over symbiont A; suggesting that symbiont abundances are modulated by these environmental changes. Overall, results showed that changes in the main Campylobacterota phylotypes in response to upwelling intensification could affect its symbiotic function in A. purpuratus under future climate change scenarios. These results provide the first insight into understanding how scallop gill-microbial systems adapt and respond to climate change stressors, which could be critical for managing health, nutrition, and scallop aquaculture productivity.
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Nishiguchi, Michele K., Edward G. Ruby, and Margaret J. McFall-Ngai. "Competitive Dominance among Strains of Luminous Bacteria Provides an Unusual Form of Evidence for Parallel Evolution in Sepiolid Squid-Vibrio Symbioses." Applied and Environmental Microbiology 64, no. 9 (September 1, 1998): 3209–13. http://dx.doi.org/10.1128/aem.64.9.3209-3213.1998.
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ABSTRACT One of the principal assumptions in symbiosis research is that associated partners have evolved in parallel. We report here experimental evidence for parallel speciation patterns among several partners of the sepiolid squid-luminous bacterial symbioses. Molecular phylogenies for 14 species of host squids were derived from sequences of both the nuclear internal transcribed spacer region and the mitochondrial cytochrome oxidase subunit I; the glyceraldehyde phosphate dehydrogenase locus was sequenced for phylogenetic determinations of 7 strains of bacterial symbionts. Comparisons of trees constructed for each of the three loci revealed a parallel phylogeny between the sepiolids and their respective symbionts. Because both the squids and their bacterial partners can be easily cultured independently in the laboratory, we were able to couple these phylogenetic analyses with experiments to examine the ability of the different symbiont strains to compete with each other during the colonization of one of the host species. Our results not only indicate a pronounced dominance of native symbiont strains over nonnative strains, but also reveal a hierarchy of symbiont competency that reflects the phylogenetic relationships of the partners. For the first time, molecular systematics has been coupled with experimental colonization assays to provide evidence for the existence of parallel speciation among a set of animal-bacterial associations.
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Blazejak, Anna, Christer Erséus, Rudolf Amann, and Nicole Dubilier. "Coexistence of Bacterial Sulfide Oxidizers, Sulfate Reducers, and Spirochetes in a Gutless Worm (Oligochaeta) from the Peru Margin." Applied and Environmental Microbiology 71, no. 3 (March 2005): 1553–61. http://dx.doi.org/10.1128/aem.71.3.1553-1561.2005.
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ABSTRACT Olavius crassitunicatus is a small symbiont-bearing worm that occurs at high abundance in oxygen-deficient sediments in the East Pacific Ocean. Using comparative 16S rRNA sequence analysis and fluorescence in situ hybridization, we examined the diversity and phylogeny of bacterial symbionts in two geographically distant O. crassitunicatus populations (separated by 385 km) on the Peru margin (water depth, ∼300 m). Five distinct bacterial phylotypes co-occurred in all specimens from both sites: two members of the γ-Proteobacteria (Gamma 1 and 2 symbionts), two members of the δ-Proteobacteria (Delta 1 and 2 symbionts), and one spirochete. A sixth phylotype belonging to the δ-Proteobacteria (Delta 3 symbiont) was found in only one of the two host populations. Three of the O. crassitunicatus bacterial phylotypes are closely related to symbionts of other gutless oligochaete species; the Gamma 1 phylotype is closely related to sulfide-oxidizing symbionts of Olavius algarvensis, Olavius loisae, and Inanidrilus leukodermatus, the Delta 1 phylotype is closely related to sulfate-reducing symbionts of O. algarvensis, and the spirochete is closely related to spirochetal symbionts of O. loisae. In contrast, the Gamma 2 phylotype and the Delta 2 and 3 phylotypes belong to novel lineages that are not related to other bacterial symbionts. Such a phylogenetically diverse yet highly specific and stable association in which multiple bacterial phylotypes coexist within a single host has not been described previously for marine invertebrates.