1
|
Goodrich-Blair H. Interactions of host-associated multispecies bacterial communities. Periodontol 2000 2021; 86:14-31. [PMID: 33690897 DOI: 10.1111/prd.12360] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The oral microbiome comprises microbial communities colonizing biotic (epithelia, mucosa) and abiotic (enamel) surfaces. Different communities are associated with health (eg, immune development, pathogen resistance) and disease (eg, tooth loss and periodontal disease). Like any other host-associated microbiome, colonization and persistence of both beneficial and dysbiotic oral microbiomes are dictated by successful utilization of available nutrients and defense against host and competitor assaults. This chapter will explore these general features of microbe-host interactions through the lens of symbiotic (mutualistic and antagonistic/pathogenic) associations with nonmammalian animals. Investigations in such systems across a broad taxonomic range have revealed conserved mechanisms and processes that underlie the complex associations among microbes and between microbes and hosts.
Collapse
Affiliation(s)
- Heidi Goodrich-Blair
- Department of Microbiology, University of Tennessee-Knoxville, Knoxville, Tennessee, USA
| |
Collapse
|
2
|
Waterworth SC, Flórez LV, Rees ER, Hertweck C, Kaltenpoth M, Kwan JC. Horizontal Gene Transfer to a Defensive Symbiont with a Reduced Genome in a Multipartite Beetle Microbiome. mBio 2020; 11:e02430-19. [PMID: 32098813 PMCID: PMC7042692 DOI: 10.1128/mbio.02430-19] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 01/13/2020] [Indexed: 12/20/2022] Open
Abstract
Symbiotic mutualisms of bacteria and animals are ubiquitous in nature, running a continuum from facultative to obligate from the perspectives of both partners. The loss of functions required for living independently but not within a host gives rise to reduced genomes in many symbionts. Although the phenomenon of genome reduction can be explained by existing evolutionary models, the initiation of the process is not well understood. Here, we describe the microbiome associated with the eggs of the beetle Lagria villosa, consisting of multiple bacterial symbionts related to Burkholderia gladioli, including a reduced-genome symbiont thought to be the exclusive producer of the defensive compound lagriamide. We show that the putative lagriamide-producing symbiont is the only member of the microbiome undergoing genome reduction and that it has already lost the majority of its primary metabolism and DNA repair pathways. The key step preceding genome reduction in the symbiont was likely the horizontal acquisition of the putative lagriamide lga biosynthetic gene cluster. Unexpectedly, we uncovered evidence of additional horizontal transfers to the symbiont's genome while genome reduction was occurring and despite a current lack of genes needed for homologous recombination. These gene gains may have given the genome-reduced symbiont a selective advantage in the microbiome, especially given the maintenance of the large lga gene cluster despite ongoing genome reduction.IMPORTANCE Associations between microorganisms and an animal, plant, or fungal host can result in increased dependence over time. This process is due partly to the bacterium not needing to produce nutrients that the host provides, leading to loss of genes that it would need to live independently and to a consequent reduction in genome size. It is often thought that genome reduction is aided by genetic isolation-bacteria that live in monocultures in special host organs, or inside host cells, have less access to other bacterial species from which they can obtain genes. Here, we describe exposure of a genome-reduced beetle symbiont to a community of related bacteria with nonreduced genomes. We show that the symbiont has acquired genes from other bacteria despite going through genome reduction, suggesting that isolation has not yet played a major role in this case of genome reduction, with horizontal gene gains still offering a potential route for adaptation.
Collapse
Affiliation(s)
- Samantha C Waterworth
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Laura V Flórez
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenburg University, Mainz, Germany
| | - Evan R Rees
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Christian Hertweck
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Products Research and Infection Biology, Jena, Germany
- Department of Natural Product Chemistry, Friedrich Schiller University, Jena, Germany
| | - Martin Kaltenpoth
- Department of Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenburg University, Mainz, Germany
| | - Jason C Kwan
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin, USA
| |
Collapse
|
3
|
Abstract
In recent years, tremendous advances have been made in our ability to characterize complex microbial communities such as the gut microbiota, and numerous surveys of the human gut microbiota have identified countless associations between different compositional attributes of the gut microbiota and adverse health conditions. However, most of these findings in humans are purely correlative and animal models are required for prospective evaluation of such changes as causative factors in disease initiation or progression. As in most fields of biomedical research, microbiota-focused studies are predominantly performed in mouse or rat models. Depending on the field of research and experimental question or objective, non-rodent models may be preferable due to better translatability or an inability to use rodents for various reasons. The following review describes the utility and limitations of several non-rodent model species for research on the microbiota and its influence on host physiology and disease. In an effort to balance the breadth of potential model species with the amount of detail provided, four model species are discussed: zebrafish, dogs, pigs, and rabbits.
Collapse
Affiliation(s)
- Aaron C Ericsson
- Department of Veterinary Pathobiology, University of Missouri, United States of America
| |
Collapse
|
4
|
Kwong WK, Medina LA, Koch H, Sing KW, Soh EJY, Ascher JS, Jaffé R, Moran NA. Dynamic microbiome evolution in social bees. SCIENCE ADVANCES 2017; 3:e1600513. [PMID: 28435856 PMCID: PMC5371421 DOI: 10.1126/sciadv.1600513] [Citation(s) in RCA: 278] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 02/10/2017] [Indexed: 05/18/2023]
Abstract
The highly social (eusocial) corbiculate bees, comprising the honey bees, bumble bees, and stingless bees, are ubiquitous insect pollinators that fulfill critical roles in ecosystem services and human agriculture. Here, we conduct wide sampling across the phylogeny of these corbiculate bees and reveal a dynamic evolutionary history behind their microbiota, marked by multiple gains and losses of gut associates, the presence of generalist as well as host-specific strains, and patterns of diversification driven, in part, by host ecology (for example, colony size). Across four continents, we found that different host species have distinct gut communities, largely independent of geography or sympatry. Nonetheless, their microbiota has a shared heritage: The emergence of the eusocial corbiculate bees from solitary ancestors appears to coincide with the acquisition of five core gut bacterial lineages, supporting the hypothesis that host sociality facilitates the development and maintenance of specialized microbiomes.
Collapse
Affiliation(s)
- Waldan K. Kwong
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06511, USA
- Department of Integrative Biology, University of Texas, Austin, Austin, TX 78712, USA
- Corresponding author. (W.K.K.); (N.A.M.)
| | - Luis A. Medina
- Department of Integrative Biology, University of Texas, Austin, Austin, TX 78712, USA
| | - Hauke Koch
- Department of Integrative Biology, University of Texas, Austin, Austin, TX 78712, USA
| | - Kong-Wah Sing
- Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Eunice Jia Yu Soh
- Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore
| | - John S. Ascher
- Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Rodolfo Jaffé
- Vale Institute of Technology, Sustainable Development, 66055-090 Belém PA, Brazil
- Department of Ecology, Universidade de São Paulo, Rua do Matão 321, 05508-090 São Paulo SP, Brazil
| | - Nancy A. Moran
- Department of Integrative Biology, University of Texas, Austin, Austin, TX 78712, USA
- Corresponding author. (W.K.K.); (N.A.M.)
| |
Collapse
|
5
|
Marden JN, McClure EA, Beka L, Graf J. Host Matters: Medicinal Leech Digestive-Tract Symbionts and Their Pathogenic Potential. Front Microbiol 2016; 7:1569. [PMID: 27790190 PMCID: PMC5061737 DOI: 10.3389/fmicb.2016.01569] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 09/20/2016] [Indexed: 12/31/2022] Open
Abstract
Digestive-tract microbiota exert tremendous influence over host health. Host-symbiont model systems are studied to investigate how symbioses are initiated and maintained, as well as to identify host processes affected by resident microbiota. The medicinal leech, Hirudo verbana, is an excellent model to address such questions owing to a microbiome that is consistently dominated by two species, Aeromonas veronii and Mucinivorans hirudinis, both of which are cultivable and have sequenced genomes. This review outlines current knowledge about the dynamics of the H. verbana microbiome. We discuss in depth the factors required for A. veronii colonization and proliferation in the leech crop and summarize the current understanding of interactions between A. veronii and its annelid host. Lastly, we discuss leech usage in modern medicine and highlight how leech-therapy associated infections, often attributable to Aeromonas spp., are of growing clinical concern due in part to an increased prevalence of fluoroquinolone resistant strains.
Collapse
Affiliation(s)
- Jeremiah N Marden
- Department of Molecular and Cell Biology, University of Connecticut, Storrs CT, USA
| | - Emily A McClure
- Department of Molecular and Cell Biology, University of Connecticut, Storrs CT, USA
| | - Lidia Beka
- Department of Molecular and Cell Biology, University of Connecticut, Storrs CT, USA
| | - Joerg Graf
- Department of Molecular and Cell Biology, University of Connecticut, StorrsCT, USA; Institute for Systems Genomics, University of Connecticut, StorrsCT, USA
| |
Collapse
|
6
|
A Tale of Transmission: Aeromonas veronii Activity within Leech-Exuded Mucus. Appl Environ Microbiol 2016; 82:2644-55. [PMID: 26896136 DOI: 10.1128/aem.00185-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 02/16/2016] [Indexed: 11/20/2022] Open
Abstract
Transmission, critical to the establishment and persistence of host-associated microbiotas, also exposes symbionts to new environmental conditions. With horizontal transmission, these different conditions represent major lifestyle shifts. Yet genome-wide analyses of how microbes adjust their transcriptomes toward these dramatic shifts remain understudied. Here, we provide a comprehensive and comparative analysis of the global transcriptional profiles of a symbiont as it shifts between lifestyles during transmission. The gammaproteobacterium Aeromonas veronii is transmitted from the gut of the medicinal leech to other hosts via host mucosal castings, yet A. veronii can also transition from mucosal habitancy to a free-living lifestyle. These three lifestyles are characterized by distinct physiological constraints and consequently lifestyle-specific changes in the expression of stress-response genes. Mucus-bound A. veronii had the greatest expression in terms of both the number of loci and levels of transcription of stress-response mechanisms. However, these bacteria are still capable of proliferating within the mucus, suggesting the availability of nutrients within this environment. We found that A. veronii alters transcription of loci in a synthetic pathway that obtains and incorporates N-acetylglucosamine (NAG; a major component of mucus) into the bacterial cell wall, enabling proliferation. Our results demonstrate that symbionts undergo dramatic local adaptation, demonstrated by widespread transcriptional changes, throughout the process of transmission that allows them to thrive while they encounter new environments which further shape their ecology and evolution.
Collapse
|
7
|
Tasiemski A, Massol F, Cuvillier-Hot V, Boidin-Wichlacz C, Roger E, Rodet F, Fournier I, Thomas F, Salzet M. Reciprocal immune benefit based on complementary production of antibiotics by the leech Hirudo verbana and its gut symbiont Aeromonas veronii. Sci Rep 2015; 5:17498. [PMID: 26635240 PMCID: PMC4669451 DOI: 10.1038/srep17498] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Accepted: 10/30/2015] [Indexed: 02/07/2023] Open
Abstract
The medicinal leech has established a long-term mutualistic association with Aeromonas veronii, a versatile bacterium which can also display free-living waterborne and fish- or human-pathogenic lifestyles. Here, we investigated the role of antibiotics in the dynamics of interaction between the leech and its gut symbiont Aeromonas. By combining biochemical and molecular approaches, we isolated and identified for the first time the antimicrobial peptides (AMPs) produced by the leech digestive tract and by its symbiont Aeromonas. Immunohistochemistry data and PCR analyses evidenced that leech AMP genes are induced in the gut epithelial cells when Aeromonas load is low (starved animals), while repressed when Aeromonas abundance is the highest (post blood feeding). The asynchronous production of AMPs by both partners suggests that these antibiotic substances (i) provide them with reciprocal protection against invasive bacteria and (ii) contribute to the unusual simplicity of the gut microflora of the leech. This immune benefit substantially reinforces the evidence of an evolutionarily stable association between H. verbana and A. veronii. Altogether these data may provide insights into the processes making the association with an Aeromonas species in the digestive tract either deleterious or beneficial.
Collapse
Affiliation(s)
- Aurélie Tasiemski
- Univ. Lille, Unité Evolution, Ecologie et Paléontologie (EEP), CNRS UMR 8198, F-59 000 Lille, France
| | - François Massol
- Univ. Lille, Unité Evolution, Ecologie et Paléontologie (EEP), CNRS UMR 8198, F-59 000 Lille, France
| | - Virginie Cuvillier-Hot
- Univ. Lille, Unité Evolution, Ecologie et Paléontologie (EEP), CNRS UMR 8198, F-59 000 Lille, France
| | - Céline Boidin-Wichlacz
- Univ. Lille, Unité Evolution, Ecologie et Paléontologie (EEP), CNRS UMR 8198, F-59 000 Lille, France
| | - Emmanuel Roger
- Univ. Lille, Centre d'infections et d'immunité de Lille, CNRS UMR 8204, INSERM U 1019, F-59 000 Lille, France
| | - Franck Rodet
- Univ. Lille, Unité Protéomique, Réponse Inflammatoire, Spectrométrie de Masse (PRISM), INSERM U 1192, F-59 000 Lille, France
| | - Isabelle Fournier
- Univ. Lille, Unité Protéomique, Réponse Inflammatoire, Spectrométrie de Masse (PRISM), INSERM U 1192, F-59 000 Lille, France
| | - Frédéric Thomas
- MIVEGEC, UMR IRD/CNRS/UM5290, 911 Avenue Agropolis, BP 64501, 34394 Montpellier Cedex 5, France
| | - Michel Salzet
- Univ. Lille, Unité Protéomique, Réponse Inflammatoire, Spectrométrie de Masse (PRISM), INSERM U 1192, F-59 000 Lille, France
| |
Collapse
|
8
|
Manzano-Marín A, Oceguera-Figueroa A, Latorre A, Jiménez-García LF, Moya A. Solving a Bloody Mess: B-Vitamin Independent Metabolic Convergence among Gammaproteobacterial Obligate Endosymbionts from Blood-Feeding Arthropods and the Leech Haementeria officinalis. Genome Biol Evol 2015; 7:2871-84. [PMID: 26454017 PMCID: PMC4684696 DOI: 10.1093/gbe/evv188] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/21/2015] [Indexed: 02/07/2023] Open
Abstract
Endosymbiosis is a common phenomenon in nature, especially between bacteria and insects, whose typically unbalanced diets are usually complemented by their obligate endosymbionts. While much interest and focus has been directed toward phloem-feeders like aphids and mealybugs, blood-feeders such as the Lone star tick (Amblyomma americanum), Glossina flies, and the human body louse (Pediculus humanus corporis) depend on obligate endosymbionts which complement their B-vitamin-deficient diets, and thus are required for growth and survival. Glossiphoniid leeches have also been found to harbor distinct endosymbionts housed in specialized organs. Here, we present the genome of the bacterial endosymbiont from Haementeria officinalis, first of a glossiphoniid leech. This as-yet-unnamed endosymbiont belongs to the Gammaproteobacteria, has a pleomorphic shape and is restricted to bacteriocytes. For this bacterial endosymbiont, we propose the name Candidatus Providencia siddallii. This symbiont possesses a highly reduced genome with high A+T content and a reduced set of metabolic capabilities, all of which are common characteristics of ancient obligate endosymbionts of arthropods. Its genome has retained many pathways related to the biosynthesis of B-vitamins, pointing toward a role in supplementing the blood-restricted diet of its host. Through comparative genomics against the endosymbionts of A. americanum, Glossina flies, and P. humanus corporis, we were able to detect a high degree of metabolic convergence among these four very distantly related endosymbiotic bacteria.
Collapse
Affiliation(s)
| | - Alejandro Oceguera-Figueroa
- Laboratorio de Helmintología, Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, Distrito Federal, Mexico
| | - Amparo Latorre
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat de València, Spain Área de Genómica y Salud de la Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunidad Valenciana (FISABIO), Valencia, Spain
| | - Luis F Jiménez-García
- Departamento de Biología Celular, Facultad de Ciencias, Universidad Nacional Autónoma de México, Distrito Federal, Mexico
| | - Andres Moya
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat de València, Spain Área de Genómica y Salud de la Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunidad Valenciana (FISABIO), Valencia, Spain
| |
Collapse
|
9
|
Ott BM, Rickards A, Gehrke L, Rio RVM. Characterization of shed medicinal leech mucus reveals a diverse microbiota. Front Microbiol 2015; 5:757. [PMID: 25620963 PMCID: PMC4288373 DOI: 10.3389/fmicb.2014.00757] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 12/12/2014] [Indexed: 11/13/2022] Open
Abstract
Microbial transmission through mucosal-mediated mechanisms is widespread throughout the animal kingdom. One example of this occurs with Hirudo verbana, the medicinal leech, where host attraction to shed conspecific mucus facilitates horizontal transmission of a predominant gut symbiont, the Gammaproteobacterium Aeromonas veronii. However, whether this mucus may harbor other bacteria has not been examined. Here, we characterize the microbiota of shed leech mucus through Illumina deep sequencing of the V3-V4 hypervariable region of the 16S rRNA gene. Additionally, Restriction Fragment Length Polymorphism (RFLP) typing with subsequent Sanger Sequencing of a 16S rRNA gene clone library provided qualitative confirmation of the microbial composition. Phylogenetic analyses of full-length 16S rRNA sequences were performed to examine microbial taxonomic distribution. Analyses using both technologies indicate the dominance of the Bacteroidetes and Proteobacteria phyla within the mucus microbiota. We determined the presence of other previously described leech symbionts, in addition to a number of putative novel leech-associated bacteria. A second predominant gut symbiont, the Rikenella-like bacteria, was also identified within mucus and exhibited similar population dynamics to A. veronii, suggesting persistence in syntrophy beyond the gut. Interestingly, the most abundant bacterial genus belonged to Pedobacter, which includes members capable of producing heparinase, an enzyme that degrades the anticoagulant, heparin. Additionally, bacteria associated with denitrification and sulfate cycling were observed, indicating an abundance of these anions within mucus, likely originating from the leech excretory system. A diverse microbiota harbored within shed mucus has significant potential implications for the evolution of microbiomes, including opportunities for gene transfer and utility in host capture of a diverse group of symbionts.
Collapse
Affiliation(s)
- Brittany M Ott
- Department of Biology, West Virginia University Morgantown, WV, USA
| | - Allen Rickards
- Department of Biology, West Virginia University Morgantown, WV, USA
| | - Lauren Gehrke
- Department of Biology, West Virginia University Morgantown, WV, USA
| | - Rita V M Rio
- Department of Biology, West Virginia University Morgantown, WV, USA
| |
Collapse
|
10
|
Hitchhiking of host biology by beneficial symbionts enhances transmission. Sci Rep 2014; 4:5825. [PMID: 25059557 PMCID: PMC5376049 DOI: 10.1038/srep05825] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 07/02/2014] [Indexed: 12/30/2022] Open
Abstract
Transmission plays a key role in the evolution of symbiosis. Mixed mode transmission combines horizontal and vertical mechanisms for symbiont acquisition. However, features that enable mixed transmission are poorly understood. Here, we determine the mechanistic basis for the recruitment of the beneficial bacterium, Aeromonas veronii by the leech, Hirudo verbana. We demonstrate that host mucosal secretions complement imperfect symbiont vertical transmission. First, we show that the A. veronii population within secretions originates from the host digestive tract and proliferates synchronously with shedding frequency, demonstrating the coupling of partner biology. Furthermore, leeches are attracted to these castings with oral contact proving sufficient for symbiont transmission. Leech attraction to mucus is not affected by the symbiont state of either the host or mucus, suggesting that A. veronii exploits preexisting host behavior and physiological traits. A dual transmission mode, integrating multiple layers of host contributions, may prove evolutionarily advantageous for a wide range of symbioses. Using such a strategy, host infection is ensured, while also providing access to a higher genetic diversity of symbionts. Countless host-associated microbes exhibit mixed mode transmission, supporting the use of the leech symbiosis as a model for enhancing our understanding of the specificity, establishment and persistence of microbiotas.
Collapse
|
11
|
Marsh SE, Poulsen M, Pinto-Tomás A, Currie CR. Interaction between workers during a short time window is required for bacterial symbiont transmission in Acromyrmex leaf-cutting ants. PLoS One 2014; 9:e103269. [PMID: 25058579 PMCID: PMC4110003 DOI: 10.1371/journal.pone.0103269] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Accepted: 06/30/2014] [Indexed: 12/26/2022] Open
Abstract
Stable associations between partners over time are critical for the evolution of mutualism. Hosts employ a variety of mechanisms to maintain specificity with bacterial associates. Acromyrmex leaf-cutting ants farm a fungal cultivar as their primary nutrient source. These ants also carry a Pseudonocardia Actinobacteria exosymbiont on their bodies that produces antifungal compounds that help inhibit specialized parasites of the ants' fungal garden. Major workers emerge from their pupal cases (eclose) symbiont-free, but exhibit visible Actinobacterial coverage within 14 days post-eclosion. Using subcolony experiments, we investigate exosymbiont transmission within Acromyrmex colonies. We found successful transmission to newly eclosed major workers fostered by major workers with visible Actinobacteria in all cases (100% acquiring, n = 19). In contrast, newly eclosed major workers reared without exosymbiont-carrying major workers did not acquire visible Actinobacteria (0% acquiring, n = 73). We further show that the majority of ants exposed to major workers with exosymbionts within 2 hours of eclosion acquired bacteria (60.7% acquiring, n = 28), while normal acquisition did not occur when exposure occurred later than 2 hours post-eclosion (0% acquiring, n = 18). Our findings show that transmission of exosymbionts to newly eclosed major workers occurs through interactions with exosymbiont-covered workers within a narrow time window after eclosion. This mode of transmission likely helps ensure the defensive function within colonies, as well as specificity and partner fidelity in the ant-bacterium association.
Collapse
Affiliation(s)
- Sarah E. Marsh
- Department of Bacteriology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Michael Poulsen
- Department of Bacteriology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Adrián Pinto-Tomás
- Departamento de Bioquímica, Facultad de Medicina, Universidad de Costa Rica, San Pedro de Montes de Oca, San José, Costa Rica
- Centro de Investigación en Estructuras Microscópicas, Universidad de Costa Rica, San Pedro de Montes de Oca, San José, Costa Rica
| | - Cameron R. Currie
- Department of Bacteriology, University of Wisconsin, Madison, Wisconsin, United States of America
- U.S. Department of Energy Great Lakes Bioenergy Research Center, University of Wisconsin, Madison, Wisconsin, United States of America
- * E-mail:
| |
Collapse
|
12
|
Davidson SK, Powell R, James S. A global survey of the bacteria within earthworm nephridia. Mol Phylogenet Evol 2012; 67:188-200. [PMID: 23268186 DOI: 10.1016/j.ympev.2012.12.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 11/29/2012] [Accepted: 12/06/2012] [Indexed: 11/18/2022]
Abstract
Earthworms comprise 16 described families in the Crassiclitellata plus a few other minor groups. Microscopy studies of the early 20th century detected bacteria within the excretory organs, the nephridia, of species within a few of these families. More recent evidence for the consistent and specific association of bacteria with nephridia within the Lumbricidae has been well documented, but the presence and identity of nephridial bacteria among the rest of the Crassiclitellata families had not been explored. The study presented here aimed to identify members of Crassiclitellata families that harbor bacteria in their nephridia, and identify these bacteria based on 16S rRNA gene sequences. Eleven earthworm families were surveyed from countries of six continents, and two island nations. The results revealed members of four bacterial orders commonly occurred within nephridia of genera within nine Crassiclitellata families. Members of the bacterial phyla Bacteroidetes (order Sphingobacteriales), Betaproteobacteria (order Burkholderiales; family Comamonadaceae), and Alphaproteobacteria (orders Rhodospirillales and Rhizobiales) were detected in the nephridia of basal Crassiclitellata, as well as in derived families. Earthworm genera with meronephridia, multiple small nephridia per segment, lacked bacteria, whereas bacteria were often detected in holonephridia, single pairs of large nephridia with a distinct morphology and external excretory pore. The Acanthodrilidae members, a large derived family of earthworms, did not appear to possess nephridial bacteria regardless of nephridial form. Although earthworms from a variety of habitat types were sampled, there were no clear correlations of lifestyle with symbiont types, with the exception of the aquatic earthworms that contained bacteria unrelated to those in any other earthworms. The findings support an evolutionarily long association of bacteria within the Crassiclitellata, and suggest a contribution to nitrogen conservation for the earthworms.
Collapse
Affiliation(s)
- Seana K Davidson
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA 98195-5014, USA.
| | | | | |
Collapse
|
13
|
Abstract
Gastrointestinal microbiomes play important roles in the health and nutrition of animals and humans. The medicinal leech, Hirudo verbana, serves as a powerful model for the study of microbial symbioses of the gut, due to its naturally limited microbiome compared with other popular models, the ability to cultivate the most abundant microbes, and genetically manipulate one of them, Aeromonas veronii. This review covers the relevance and application of leeches in modern medicine as well as recent discoveries detailing the nature of the gut microbiome. Additionally, the dual life-style of A. veronii allows one to do direct comparisons between colonization factors for beneficial and pathogenic associations, and relevant findings are detailed with respect to their role within the host and pathogenicity to other animals.
Collapse
|
14
|
Goffredi SK, Morella NM, Pulcrano ME. Affiliations between bacteria and marine fish leeches (Piscicolidae), with emphasis on a deep-sea species from Monterey Canyon, CA. Environ Microbiol 2012; 14:2429-44. [PMID: 22681178 DOI: 10.1111/j.1462-2920.2012.02798.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Leeches within the Piscicolidae are of great numerical and taxonomic importance, yet little is known about bacteria that associate with this diverse group of blood-feeding marine parasites of fish and elasmobranchs. We focused primarily on the bacteria from a deep-sea leech species of unknown identity, collected at ∼ 600 m depth in Monterey Canyon, CA, along with two shallow-living leech genera, Austrobdella and Branchellion, from Los Angeles Harbor, CA. Molecular analysis of all five leech species revealed a dominance of gammaproteobacteria, which were distinct from each other and from previously reported freshwater leech symbionts. Bacteria related to members of the genus Psychromonas (99% similarity in 16S rRNA) were dominant in the deep-sea leech species (80-94% of recovered ribotypes) collected over 19 months from two different locations. Psychromonas was not detected in cocoons or 2-16 week-old juveniles, suggesting that acquisition is via the environment at a later stage. Transmission electron microscopy did, however, reveal abundant bacteria-like cells near areas of thinning of the juvenile epithelial surface, as well as Psychromonas sparsely distributed internally. Electron and fluorescence in situ microscopy of adults also showed Psychromonas-like bacteria concentrated within the crop. Despite the apparent non-transient nature of the association between Psychromonas and the deep-sea leech, their functional role, if any, is not known. The prevalence, however, of an abundant bacterial genus in one piscicolid leech species, as well as the presence of a dominant bacterial species in singular observations of four additional marine species, suggests that members of the Piscicolidae, possibly basal within the class Hirudinea, form specific alliances with microbes.
Collapse
Affiliation(s)
- S K Goffredi
- Biology Department, Occidental College, Los Angeles, CA, USA.
| | | | | |
Collapse
|
15
|
Silver A, Graf J. Innate and procured immunity inside the digestive tract of the medicinal leech. INVERTEBRATE SURVIVAL JOURNAL : ISJ 2011; 8:173-178. [PMID: 22461860 PMCID: PMC3313596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Especially when combined with unique biological adaptations, invertebrate animals provide important insights into innate immunity because the immune response is not complicated by adaptive immunity that vertebrates evolved. One such example is the digestive tract of the medicinal leech, Hirudo verbana, which is unusual in two aspects, it contains a simple microbial community and it stores large amounts of vertebrate blood for a several months. In this review we will discuss aspects of the innate immunity of the leech and from the ingested blood that we term procured immunity to differentiate it from the immunity encoded by the leech genome.
Collapse
Affiliation(s)
- Ac Silver
- Department of Internal Medicine, Section of Infectious Diseases, Yale University School of Medicine, New Haven, CT 06520, USA
| | | |
Collapse
|
16
|
Abstract
The evolutionary history of leeches is employed as a general framework for understanding more than merely the systematics of this charismatic group of annelid worms, and serves as a basis for understanding blood-feeding related correlates ranging from the specifics of gut-associated bacterial symbionts to salivary anticoagulant peptides. A variety of medicinal leech families were examined for intraluminal crop bacterial symbionts. Species of Aeromonas and Bacteroidetes were characterized with DNA gyrase B and 16S rDNA. Bacteroidetes isolates were found to be much more phylogenetically diverse and suggested stronger evidence of phylogenetic correlation than the gammaproteobacteria. Patterns that look like co-speciation with limited taxon sampling do not in the full context of phylogeny. Bioactive compounds that are expressed as gene products, like those in leech salivary glands, have 'passed the test' of evolutionary selection. We produced and bioinformatically mined salivary gland EST libraries across medicinal leech lineages to experimentally and statistically evaluate whether evolutionary selection on peptides can identify structure-function activities of known therapeutically relevant bioactive compounds like antithrombin, hirudin and antistasin. The combined information content of a well corroborated leech phylogeny and broad taxonomic coverage of expressed proteins leads to a rich understanding of evolution and function in leech history.
Collapse
|
17
|
Bomar L, Maltz M, Colston S, Graf J. Directed culturing of microorganisms using metatranscriptomics. mBio 2011; 2:e00012-11. [PMID: 21467263 PMCID: PMC3069634 DOI: 10.1128/mbio.00012-11] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Accepted: 03/08/2011] [Indexed: 12/16/2022] Open
Abstract
UNLABELLED The vast majority of bacterial species remain uncultured, and this severely limits the investigation of their physiology, metabolic capabilities, and role in the environment. High-throughput sequencing of RNA transcripts (RNA-seq) allows the investigation of the diverse physiologies from uncultured microorganisms in their natural habitat. Here, we report the use of RNA-seq for characterizing the metatranscriptome of the simple gut microbiome from the medicinal leech Hirudo verbana and for utilizing this information to design a medium for cultivating members of the microbiome. Expression data suggested that a Rikenella-like bacterium, the most abundant but uncultured symbiont, forages on sulfated- and sialated-mucin glycans that are fermented, leading to the secretion of acetate. Histological stains were consistent with the presence of sulfated and sialated mucins along the crop epithelium. The second dominant symbiont, Aeromonas veronii, grows in two different microenvironments and is predicted to utilize either acetate or carbohydrates. Based on the metatranscriptome, a medium containing mucin was designed, which enabled the cultivation of the Rikenella-like bacterium. Metatranscriptomes shed light on microbial metabolism in situ and provide critical clues for directing the culturing of uncultured microorganisms. By choosing a condition under which the desired organism is rapidly proliferating and focusing on highly expressed genes encoding hydrolytic enzymes, binding proteins, and transporters, one can identify an organism's nutritional preferences and design a culture medium. IMPORTANCE The number of prokaryotes on the planet has been estimated to exceed 10(30) cells, and the overwhelming majority of them have evaded cultivation, making it difficult to investigate their ecological, medical, and industrial relevance. The application of transcriptomics based on high-throughput sequencing of RNA transcripts (RNA-seq) to microorganisms in their natural environment can provide investigators with insight into their physiologies under optimal growth conditions. We utilized RNA-seq to learn more about the uncultured and cultured symbionts that comprise the relatively simple digestive-tract microbiome of the medicinal leech. The expression data revealed highly expressed hydrolytic enzymes and transporters that provided critical clues for the design of a culture medium enabling the isolation of the previously uncultured Rikenella-like symbiont. This directed culturing method will greatly aid efforts aimed at understanding uncultured microorganisms, including beneficial symbionts, pathogens, and ecologically relevant microorganisms, by facilitating genome sequencing, physiological characterization, and genetic manipulation of the previously uncultured microbes.
Collapse
Affiliation(s)
- Lindsey Bomar
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, USA
| | | | - Sophie Colston
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Joerg Graf
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, USA
| |
Collapse
|
18
|
Complex evolutionary history of the Aeromonas veronii group revealed by host interaction and DNA sequence data. PLoS One 2011; 6:e16751. [PMID: 21359176 PMCID: PMC3040217 DOI: 10.1371/journal.pone.0016751] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Accepted: 01/10/2011] [Indexed: 12/23/2022] Open
Abstract
Aeromonas veronii biovar sobria, Aeromonas veronii biovar veronii, and Aeromonas allosaccharophila are a closely related group of organisms, the Aeromonas veronii Group, that inhabit a wide range of host animals as a symbiont or pathogen. In this study, the ability of various strains to colonize the medicinal leech as a model for beneficial symbiosis and to kill wax worm larvae as a model for virulence was determined. Isolates cultured from the leech out-competed other strains in the leech model, while most strains were virulent in the wax worms. Three housekeeping genes, recA, dnaJ and gyrB, the gene encoding chitinase, chiA, and four loci associated with the type three secretion system, ascV, ascFG, aexT, and aexU were sequenced. The phylogenetic reconstruction failed to produce one consensus tree that was compatible with most of the individual genes. The Approximately Unbiased test and the Genetic Algorithm for Recombination Detection both provided further support for differing evolutionary histories among this group of genes. Two contrasting tests detected recombination within aexU, ascFG, ascV, dnaJ, and gyrB but not in aexT or chiA. Quartet decomposition analysis indicated a complex recent evolutionary history for these strains with a high frequency of horizontal gene transfer between several but not among all strains. In this study we demonstrate that at least for some strains, horizontal gene transfer occurs at a sufficient frequency to blur the signal from vertically inherited genes, despite strains being adapted to distinct niches. Simply increasing the number of genes included in the analysis is unlikely to overcome this challenge in organisms that occupy multiple niches and can exchange DNA between strains specialized to different niches. Instead, the detection of genes critical in the adaptation to specific niches may help to reveal the physiological specialization of these strains.
Collapse
|
19
|
Davidson SK, Powell RJ, Stahl DA. Transmission of a bacterial consortium in Eisenia fetida egg capsules. Environ Microbiol 2010; 12:2277-88. [PMID: 21966919 DOI: 10.1111/j.1462-2920.2010.02231.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The earthworm Eisenia fetida harbours Verminephrobacter eiseniae within their excretory nephridia. This symbiont is transferred from the parent into the egg capsules where the cells are acquired by the developing earthworm in a series of recruitment steps. Previous studies defined V. eiseniae as the most abundant cell type in the egg capsules, leaving approximately 30% of the bacteria unidentified and of unknown origin. The study presented here used terminal restriction fragment length polymorphism analysis together with cloning and sequencing of 16S rRNA genes to define the composition of the bacterial consortium in E. fetida egg capsules from early to late development. Newly formed capsules of E. fetida contained three bacterial types, a novel Microbacteriaceae member, a Flexibacteriaceae member and the previously described V. eiseniae. Fluorescent in situ hybridization (FISH) using specific and general rRNA probes demonstrated that the bacteria are abundant during early development, colonize the embryo and appear in the adult nephridia. As the capsules mature, Herbaspirillum spp. become abundant although they were not detected within the adult worm. These divergent taxa could serve distinct functions in both the adult earthworm and in the egg capsule to influence the competitive ability of earthworms within the soil community.
Collapse
Affiliation(s)
- Seana K Davidson
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA 98195-5014, USA.
| | | | | |
Collapse
|
20
|
Abstract
The perpetuation of symbioses through host generations relies on symbiont transmission. Horizontally transmitted symbionts are taken up from the environment anew by each host generation, and vertically transmitted symbionts are most often transferred through the female germ line. Mixed modes also exist. In this Review we describe the journey of symbionts from the initial contact to their final residence. We provide an overview of the molecular mechanisms that mediate symbiont attraction and accumulation, interpartner recognition and selection, as well as symbiont confrontation with the host immune system. We also discuss how the two main transmission modes shape the evolution of the symbiotic partners.
Collapse
Affiliation(s)
- Monika Bright
- University of Vienna, Department of Marine Biology, Althanstrasse 14, A-1090 Vienna, Austria.
| | | |
Collapse
|