1
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Patel M, West S. Microbial warfare and the evolution of symbiosis. Biol Lett 2022; 18:20220447. [PMID: 36541095 PMCID: PMC9768647 DOI: 10.1098/rsbl.2022.0447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Cooperative symbionts enable their hosts to exploit a diversity of environments. A low genetic diversity (high relatedness) between the symbionts within a host is thought to favour cooperation by reducing conflict within the host. However, hosts will not be favoured to transmit their symbionts (or commensals) in costly ways that increase relatedness, unless this also provides an immediate fitness benefit to the host. We suggest that conditionally expressed costly competitive traits, such as antimicrobial warfare with bacteriocins, could provide a relatively universal reason for why hosts would gain an immediate benefit from increasing the relatedness between symbionts. We theoretically test this hypothesis with a simple illustrative model that examines whether hosts should manipulate relatedness, and an individual-based simulation, where host control evolves in a structured population. We find that hosts can be favoured to manipulate relatedness, to reduce conflict between commensals via this immediate reduction in warfare. Furthermore, this manipulation evolves to extremes of high or low vertical transmission and only in a narrow range is partly vertical transmission stable.
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Affiliation(s)
- Matishalin Patel
- Centre for the Future of Intelligence, University of Cambridge, Cambridge, Cambridgeshire CB2 1SB, UK
| | - Stuart West
- Department of Zoology, University of Oxford, Oxford OX1 2JD, UK
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2
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Dinges ZM, Phillips RK, Lively CM, Bashey F. Post‐association barrier to host switching maintained despite strong selection in a novel mutualism. Ecol Evol 2022; 12:e9011. [PMID: 35784049 PMCID: PMC9204852 DOI: 10.1002/ece3.9011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 05/17/2022] [Accepted: 05/20/2022] [Indexed: 11/25/2022] Open
Abstract
Following a host shift, repeated co‐passaging of a mutualistic pair is expected to increase fitness over time in one or both species. Without adaptation, a novel association may be evolutionarily short‐lived as it is likely to be outcompeted by native pairings. Here, we test whether experimental evolution can rescue a low‐fitness novel pairing between two sympatric species of Steinernema nematodes and their symbiotic Xenorhabdus bacteria. Despite low mean fitness in the novel association, considerable variation in nematode reproduction was observed across replicate populations. We selected the most productive infections, co‐passaging this novel mutualism nine times to determine whether selection could improve the fitness of either or both partners. We found that neither partner showed increased fitness over time. Our results suggest that the variation in association success was not heritable and that mutational input was insufficient to allow evolution to facilitate this host shift. Thus, post‐association costs of host switching may represent a formidable barrier to novel partnerships among sympatric mutualists.
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Affiliation(s)
- Zoe M. Dinges
- Department of Biology Indiana University Bloomington Indiana USA
| | | | - Curtis M. Lively
- Department of Biology Indiana University Bloomington Indiana USA
| | - Farrah Bashey
- Department of Biology Indiana University Bloomington Indiana USA
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3
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Carim S, Azadeh AL, Kazakov AE, Price MN, Walian PJ, Lui LM, Nielsen TN, Chakraborty R, Deutschbauer AM, Mutalik VK, Arkin AP. Systematic discovery of pseudomonad genetic factors involved in sensitivity to tailocins. THE ISME JOURNAL 2021; 15:2289-2305. [PMID: 33649553 PMCID: PMC8319346 DOI: 10.1038/s41396-021-00921-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 01/14/2021] [Accepted: 02/01/2021] [Indexed: 12/13/2022]
Abstract
Tailocins are bactericidal protein complexes produced by a wide variety of bacteria that kill closely related strains and may play a role in microbial community structure. Thanks to their high specificity, tailocins have been proposed as precision antibacterial agents for therapeutic applications. Compared to tailed phages, with whom they share an evolutionary and morphological relationship, bacterially produced tailocins kill their host upon production but producing strains display resistance to self-intoxication. Though lipopolysaccharide (LPS) has been shown to act as a receptor for tailocins, the breadth of factors involved in tailocin sensitivity, and the mechanisms behind resistance to self-intoxication, remain unclear. Here, we employed genome-wide screens in four non-model pseudomonads to identify mutants with altered fitness in the presence of tailocins produced by closely related pseudomonads. Our mutant screens identified O-antigen composition and display as most important in defining sensitivity to our tailocins. In addition, the screens suggest LPS thinning as a mechanism by which resistant strains can become more sensitive to tailocins. We validate many of these novel findings, and extend these observations of tailocin sensitivity to 130 genome-sequenced pseudomonads. This work offers insights into tailocin-bacteria interactions, informing the potential use of tailocins in microbiome manipulation and antibacterial therapy.
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Affiliation(s)
- Sean Carim
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA
| | - Ashley L Azadeh
- Innovative Genomics Institute, University of California, Berkeley, CA, USA
| | - Alexey E Kazakov
- Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Morgan N Price
- Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Peter J Walian
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Lauren M Lui
- Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Torben N Nielsen
- Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Romy Chakraborty
- Climate and Ecosystem Sciences, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Adam M Deutschbauer
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA
- Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Vivek K Mutalik
- Innovative Genomics Institute, University of California, Berkeley, CA, USA.
- Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Adam P Arkin
- Innovative Genomics Institute, University of California, Berkeley, CA, USA.
- Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Department of Bioengineering, University of California, Berkeley, CA, USA.
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4
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Thappeta KRV, Ciezki K, Morales-Soto N, Wesener S, Goodrich-Blair H, Stock SP, Forst S. R-type bacteriocins of Xenorhabdus bovienii determine the outcome of interspecies competition in a natural host environment. MICROBIOLOGY-SGM 2020; 166:1074-1087. [PMID: 33064635 DOI: 10.1099/mic.0.000981] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Xenorhabdus species are bacterial symbionts of Steinernema nematodes and pathogens of susceptible insects. Different species of Steinernema nematodes carrying specific species of Xenorhabdus can invade the same insect, thereby setting up competition for nutrients within the insect environment. While Xenorhabdus species produce both diverse antibiotic compounds and prophage-derived R-type bacteriocins (xenorhabdicins), the functions of these molecules during competition in a host are not well understood. Xenorhabdus bovienii (Xb-Sj), the symbiont of Steinernema jollieti, possesses a remnant P2-like phage tail cluster, xbp1, that encodes genes for xenorhabdicin production. We show that inactivation of either tail sheath (xbpS1) or tail fibre (xbpH1) genes eliminated xenorhabdicin production. Preparations of Xb-Sj xenorhabdicin displayed a narrow spectrum of activity towards other Xenorhabdus and Photorhabdus species. One species, Xenorhabdus szentirmaii (Xsz-Sr), was highly sensitive to Xb-Sj xenorhabdicin but did not produce xenorhabdicin that was active against Xb-Sj. Instead, Xsz-Sr produced high-level antibiotic activity against Xb-Sj when grown in complex medium and lower levels when grown in defined medium (Grace's medium). Conversely, Xb-Sj did not produce detectable levels of antibiotic activity against Xsz-Sr. To study the relative contributions of Xb-Sj xenorhabdicin and Xsz-Sr antibiotics in interspecies competition in which the respective Xenorhabdus species produce antagonistic activities against each other, we co-inoculated cultures with both Xenorhabdus species. In both types of media Xsz-Sr outcompeted Xb-Sj, suggesting that antibiotics produced by Xsz-Sr determined the outcome of the competition. In contrast, Xb-Sj outcompeted Xsz-Sr in competitions performed by co-injection in the insect Manduca sexta, while in competition with the xenorhabdicin-deficient strain (Xb-Sj:S1), Xsz-Sr was dominant. Thus, xenorhabdicin was required for Xb-Sj to outcompete Xsz-Sr in a natural host environment. These results highlight the importance of studying the role of antagonistic compounds under natural biological conditions.
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Affiliation(s)
- Kishore Reddy Venkata Thappeta
- University of Wisconsin, Milwaukee, WI, USA.,Singapore Institute of Food and Biotechnology Innovation (SIFBI), A*STAR, Singapore
| | - Kristin Ciezki
- Aurora Health Care, Milwaukee, WI, USA.,University of Wisconsin, Milwaukee, WI, USA
| | - Nydia Morales-Soto
- Eck Institute for Global Health, University of Notre Dame, IN, USA.,University of Wisconsin, Milwaukee, WI, USA
| | | | - Heidi Goodrich-Blair
- University of Tennessee, Knoxville, TN, USA.,University of Wisconsin, Madison, WI, USA
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5
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Bhattacharya A, Toro Díaz VC, Morran LT, Bashey F. Evolution of increased virulence is associated with decreased spite in the insect-pathogenic bacterium Xenorhabdus nematophila. Biol Lett 2019; 15:20190432. [PMID: 31455168 DOI: 10.1098/rsbl.2019.0432] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Disease virulence may be strongly influenced by social interactions among pathogens, both during the time course of an infection and evolutionarily. Here, we examine how spiteful bacteriocin production in the insect-pathogenic bacterium Xenorhabdus nematophila is evolutionarily linked to its virulence. We expected a negative correlation between virulence and spite owing to their inverse correlations with growth. We examined bacteriocin production and growth across 14 experimentally evolved lineages that show faster host-killing relative to their ancestral population. Consistent with expectations, these more virulent lineages showed reduced bacteriocin production and faster growth relative to the ancestor. Further, bacteriocin production was negatively correlated with growth across the examined lineages. These results strongly support an evolutionary trade-off between virulence and bacteriocin production and lend credence to the view that disease management can be improved by exploiting pathogen social interactions.
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Affiliation(s)
- Amrita Bhattacharya
- Department of Biology, Indiana University Bloomington, 1001 E 3rd Street, Bloomington, IN, USA
| | - Valeria C Toro Díaz
- Department of Biology, Indiana University Bloomington, 1001 E 3rd Street, Bloomington, IN, USA
| | - Levi T Morran
- Department of Biology, Emory University, 1510 Clifton Road NE, Atlanta, GA, USA
| | - Farrah Bashey
- Department of Biology, Indiana University Bloomington, 1001 E 3rd Street, Bloomington, IN, USA
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6
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Bhattacharya A, Stacy A, Bashey F. Suppression of bacteriocin resistance using live, heterospecific competitors. Evol Appl 2019; 12:1191-1200. [PMID: 31293631 PMCID: PMC6597863 DOI: 10.1111/eva.12797] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 03/15/2019] [Accepted: 03/21/2019] [Indexed: 12/21/2022] Open
Abstract
Rapidly spreading antibiotic resistance has led to the need for novel alternatives and sustainable strategies for antimicrobial use. Bacteriocins are a class of proteinaceous anticompetitor toxins under consideration as novel therapeutic agents. However, bacteriocins, like other antimicrobial agents, are susceptible to resistance evolution and will require the development of sustainable strategies to prevent or decelerate the evolution of resistance. Here, we conduct proof-of-concept experiments to test whether introducing a live, heterospecific competitor along with a bacteriocin dose can effectively suppress the emergence of bacteriocin resistance in vitro. Previous work with conventional chemotherapeutic agents suggests that competition between conspecific sensitive and resistant pathogenic cells can effectively suppress the emergence of resistance in pathogenic populations. However, the threshold of sensitive cells required for such competitive suppression of resistance may often be too high to maintain host health. Therefore, here we aim to ask whether the principle of competitive suppression can be effective if a heterospecific competitor is used. Our results show that a live competitor introduced in conjunction with low bacteriocin dose can effectively control resistance and suppress sensitive cells. Further, this efficacy can be matched by using a bacteriocin-producing competitor without any additional bacteriocin. These results provide strong proof of concept for the effectiveness of competitive suppression using live, heterospecific competitors. Currently used probiotic strains or commensals may provide promising candidates for the therapeutic use of bacteriocin-mediated competitive suppression.
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Affiliation(s)
| | | | - Farrah Bashey
- Department of BiologyIndiana UniversityBloomingtonIndiana
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7
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Karvonen A, Jokela J, Laine AL. Importance of Sequence and Timing in Parasite Coinfections. Trends Parasitol 2018; 35:109-118. [PMID: 30578150 DOI: 10.1016/j.pt.2018.11.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 11/21/2018] [Accepted: 11/25/2018] [Indexed: 12/17/2022]
Abstract
Coinfections by multiple parasites predominate in the wild. Interactions between parasites can be antagonistic, neutral, or facilitative, and they can have significant implications for epidemiology, disease dynamics, and evolution of virulence. Coinfections commonly result from sequential exposure of hosts to different parasites. We argue that the sequential nature of coinfections is important for the consequences of infection in both natural and man-made environments. Coinfections accumulate during host lifespan, determining the structure of the parasite infracommunity. Interactions within the parasite community and their joint effect on the host individual potentially shape evolution of parasite life-history traits and transmission biology. Overall, sequential coinfections have the potential to change evolutionary and epidemiological outcomes of host-parasite interactions widely across plant and animal systems.
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Affiliation(s)
- Anssi Karvonen
- University of Jyvaskyla, Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyvaskyla, Finland.
| | - Jukka Jokela
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland; ETH Zürich, Institute of Integrative Biology (IBZ), 8092 Zürich, Switzerland
| | - Anna-Liisa Laine
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, 8057 Zürich, Switzerland; Research Centre for Ecological Change, Organismal & Evolutionary Biology, P.O. Box 65 (Viikinkaari 1), FI-00014 University of Helsinki, Finland
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8
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Fortuna TM, Namias A, Snirc A, Branca A, Hood ME, Raquin C, Shykoff JA, Giraud T. Multiple infections, relatedness and virulence in the anther-smut fungus castrating Saponaria plants. Mol Ecol 2018; 27:4947-4959. [PMID: 30372557 DOI: 10.1111/mec.14911] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 09/28/2018] [Accepted: 10/08/2018] [Indexed: 11/26/2022]
Abstract
Multiple infections (co-occurrence of multiple pathogen genotypes within an individual host) can have important impacts on diseases. Relatedness among pathogens can affect the likelihood of multiple infections and their consequences through kin selection. Previous studies on the castrating anther-smut fungus Microbotryum lychnidis-dioicae have shown that multiple infections occur in its host plant Silene latifolia. Relatedness was high among fungal genotypes within plants, which could result from competitive exclusion between unrelated fungal genotypes, from population structure or from interactions between plant and fungal genotypes for infection ability. Here, we aimed at disentangling these hypotheses using M. saponariae and its host Saponaria officinalis, both experimentally tractable for these questions. By analysing populations using microsatellite markers, we also found frequent occurrence of multiple infections and high relatedness among strains within host plants. Infections resulting from experimental inoculations in the greenhouse also revealed high relatedness among strains co-infecting host plants, even in clonally replicated plant genotypes, indicating that high relatedness within plants did not result merely from plant x fungus interactions or population structure. Furthermore, hyphal growth in vitro was affected by the presence of a competitor growing nearby and by its genetic similarity, although this latter effect was strain-dependent. Altogether, our results support the hypothesis that relatedness-dependent competitive exclusion occurs in Microbotryum fungi within plants. These microorganisms can thus respond to competitors and to their level of relatedness.
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Affiliation(s)
- Taiadjana M Fortuna
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, France
| | - Alice Namias
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, France.,Département de Biologie, Ecole Normale Supérieure, PSL Research University, Paris, France
| | - Alodie Snirc
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, France
| | - Antoine Branca
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, France
| | - Michael E Hood
- Department of Biology, Amherst College, Amherst, Massachusetts
| | - Christian Raquin
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, France
| | - Jacqui A Shykoff
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, France
| | - Tatiana Giraud
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, France
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9
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Bertoloni Meli S, Bashey F. Trade-off between reproductive and anti-competitor abilities in an insect-parasitic nematode-bacteria symbiosis. Ecol Evol 2018; 8:10847-10856. [PMID: 30519411 PMCID: PMC6262920 DOI: 10.1002/ece3.4538] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 06/27/2018] [Accepted: 08/18/2018] [Indexed: 11/29/2022] Open
Abstract
Mutualistic symbionts can provide diverse benefits to their hosts and often supply key trait variation for host adaptation. The bacterial symbionts of entomopathogenic nematodes play a crucial role in successful colonization of and reproduction in the insect host. Additionally, these symbionts can produce a diverse array of antimicrobial compounds to deter within-host competitors. Natural isolates of the symbiont, Xenorhabdus bovienii, show considerable variation in their ability to target sympatric competitors via bacteriocins, which can inhibit the growth of sensitive Xenorhabdus strains. Both the bacteria and its nematode partner have been shown to benefit from bacteriocin production when within-host competition with a sensitive competitor occurs. Despite this benefit, several isolates of Xenorhabdus do not inhibit sympatric strains. To understand how this variation in allelopathy could be maintained, we tested the hypothesis that inhibiting isolates face a reproductive cost in the absence of competition. We tested this hypothesis by examining the reproductive success of inhibiting and non-inhibiting isolates coupled with their natural nematode host in a non-competitive context. We found that nematodes carrying non-inhibitors killed the insect host more rapidly and were more likely to successfully reproduce than nematodes carrying inhibitors. Lower reproductive success of inhibiting isolates was repeatable across nematode generations and across insect host species. However, no difference in insect mortality was observed between inhibiting and non-inhibiting isolates when bacteria were injected into insects without their nematode partners. Our results indicate a trade-off between the competitive and reproductive roles of symbionts, such that inhibiting isolates, which are better in the face of within-host competition, pay a reproductive cost in the absence of competition. Furthermore, our results support the hypothesis that symbiont variation within populations can be maintained through context-dependent fitness benefits conferred to their hosts. As such, our study offers novel insights into the selective forces maintaining variation within a single host-symbiont population and highlights the role of competition in mutualism evolution.
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Affiliation(s)
| | - Farrah Bashey
- Department of BiologyIndiana UniversityBloomingtonIndiana
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10
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Bhattacharya A, Pak HT, Bashey F. Plastic responses to competition: Does bacteriocin production increase in the presence of nonself competitors? Ecol Evol 2018; 8:6880-6888. [PMID: 30073052 PMCID: PMC6065276 DOI: 10.1002/ece3.4203] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 03/15/2018] [Accepted: 04/17/2018] [Indexed: 11/07/2022] Open
Abstract
Anticompetitor traits such as the production of allelopathic toxins can confer significant competitive benefits but are often costly to produce. Evolution of these traits may be facilitated by environment-specific induction; however, the extent to which costly anticompetitor traits are induced by competitors is not well explored. Here, we addressed this question using bacteriocins, which are highly specific, proteinaceous anticompetitor toxins, produced by most lineages of bacteria and archaea. We tested the prediction that bacteriocin production is phenotypically plastic and induced by the presence of competitors by examining bacteriocin production in the presence and absence of nonself competitors over the course of growth of a producing strain. Our results show that bacteriocin production is detectable only at high cell densities, when competition for resources is high. However, the amount of bacteriocin activity was not significantly different in the presence vs. the absence of nonself competitors. These results suggest that bacteriocin production is either (a) canalized, constitutively produced by a fixed frequency of cells in the population or (b) induced by generic cues of competition, rather than specific self/nonself discrimination. Such a nonspecific response to competition could be favored in the natural environment where competition is ubiquitous.
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Affiliation(s)
| | | | - Farrah Bashey
- Department of BiologyIndiana UniversityBloomingtonIndiana
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11
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Kinnula H, Mappes J, Sundberg LR. Coinfection outcome in an opportunistic pathogen depends on the inter-strain interactions. BMC Evol Biol 2017; 17:77. [PMID: 28288561 PMCID: PMC5348763 DOI: 10.1186/s12862-017-0922-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 02/22/2017] [Indexed: 11/11/2022] Open
Abstract
Background In nature, organisms are commonly coinfected by two or more parasite strains, which has been shown to influence disease virulence. Yet, the effects of coinfections of environmental opportunistic pathogens on disease outcome are still poorly known, although as host-generalists they are highly likely to participate in coinfections. We asked whether coinfection with conspecific opportunistic strains leads to changes in virulence, and if these changes are associated with bacterial growth or interference competition. We infected zebra fish (Danio rerio) with three geographically and/or temporally distant environmental opportunist Flavobacterium columnare strains in single and in coinfection. Growth of the strains was studied in single and in co-cultures in liquid medium, and interference competition (growth-inhibiting ability) on agar. Results The individual strains differed in their virulence, growth and ability for interference competition. Number of coinfecting strains significantly influenced the virulence of infection, with three-strain coinfection differing from the two-strain and single infections. Differences in virulence seemed to associate with the identity of the coinfecting bacterial strains, and their pairwise interactions. This indicates that benefits of competitive ability (production of growth-inhibiting compounds) for virulence are highest when multiple strains co-occur, whereas the high virulence in coinfection may be independent from in vitro bacterial growth. Conclusions Intraspecific competition can lead to plastic increase in virulence, likely caused by faster utilization of host resources stimulated by the competitive interactions between the strains. However, disease outcome depends both on the characteristics of individual strains and their interactions. Our results highlight the importance of strain interactions in disease dynamics in environments where various pathogen genotypes co-occur. Electronic supplementary material The online version of this article (doi:10.1186/s12862-017-0922-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Hanna Kinnula
- Department of Biological and Environmental Science (and Nanoscience Center), Jyvaskyla, Finland
| | - Johanna Mappes
- Department of Biological and Environmental Science (and Nanoscience Center), Jyvaskyla, Finland
| | - Lotta-Riina Sundberg
- Department of Biological and Environmental Science (and Nanoscience Center), Jyvaskyla, Finland.
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12
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Sundberg LR, Ketola T, Laanto E, Kinnula H, Bamford JKH, Penttinen R, Mappes J. Intensive aquaculture selects for increased virulence and interference competition in bacteria. Proc Biol Sci 2016; 283:20153069. [PMID: 26936249 DOI: 10.1098/rspb.2015.3069] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Although increased disease severity driven by intensive farming practices is problematic in food production, the role of evolutionary change in disease is not well understood in these environments. Experiments on parasite evolution are traditionally conducted using laboratory models, often unrelated to economically important systems. We compared how the virulence, growth and competitive ability of a globally important fish pathogen, Flavobacterium columnare, change under intensive aquaculture. We characterized bacterial isolates from disease outbreaks at fish farms during 2003-2010, and compared F. columnare populations in inlet water and outlet water of a fish farm during the 2010 outbreak. Our data suggest that the farming environment may select for bacterial strains that have high virulence at both long and short time scales, and it seems that these strains have also evolved increased ability for interference competition. Our results are consistent with the suggestion that selection pressures at fish farms can cause rapid changes in pathogen populations, which are likely to have long-lasting evolutionary effects on pathogen virulence. A better understanding of these evolutionary effects will be vital in prevention and control of disease outbreaks to secure food production.
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Affiliation(s)
- Lotta-Riina Sundberg
- University of Jyvaskyla, Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science (and Nanoscience Centre), PO Box 35, Jyvaskyla 40014, Finland
| | - Tarmo Ketola
- University of Jyvaskyla, Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science (and Nanoscience Centre), PO Box 35, Jyvaskyla 40014, Finland
| | - Elina Laanto
- University of Jyvaskyla, Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science (and Nanoscience Centre), PO Box 35, Jyvaskyla 40014, Finland
| | - Hanna Kinnula
- University of Jyvaskyla, Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science (and Nanoscience Centre), PO Box 35, Jyvaskyla 40014, Finland
| | - Jaana K H Bamford
- University of Jyvaskyla, Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science (and Nanoscience Centre), PO Box 35, Jyvaskyla 40014, Finland
| | - Reetta Penttinen
- University of Jyvaskyla, Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science (and Nanoscience Centre), PO Box 35, Jyvaskyla 40014, Finland
| | - Johanna Mappes
- University of Jyvaskyla, Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science (and Nanoscience Centre), PO Box 35, Jyvaskyla 40014, Finland
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13
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Ciezki K, Murfin K, Goodrich-Blair H, Stock SP, Forst S. R-type bacteriocins in related strains of Xenorhabdus bovienii: Xenorhabdicin tail fiber modularity and contribution to competitiveness. FEMS Microbiol Lett 2016; 364:fnw235. [PMID: 27737947 DOI: 10.1093/femsle/fnw235] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 02/25/2016] [Accepted: 10/11/2016] [Indexed: 01/09/2023] Open
Abstract
R-type bacteriocins are contractile phage tail-like structures that are bactericidal towards related bacterial species. The C-terminal region of the phage tail fiber protein determines target-binding specificity. The mutualistic bacteria Xenorhabdus nematophila and X. bovienii produce R-type bacteriocins (xenorhabdicins) that are selectively active against different Xenorhabdus species. We analyzed the P2-type remnant prophage clusters in draft sequences of nine strains of X. bovienii The C-terminal tail fiber region in each of the respective strains was unique and consisted of mosaics of modular units. The region between the main tail fiber gene (xbpH1) and the sheath gene (xbpS1) contained a variable number of modules encoding tail fiber fragments. DNA inversion and module exchange between strains was involved in generating tail fiber diversity. Xenorhabdicin-enriched fractions from three different X. bovienii strains isolated from the same nematode species displayed distinct activities against each other. In one set of strains, the strain that produced highly active xenorhabdicin was able to eliminate a sensitive strain. In contrast, xenorhabdicin activity was not a determining factor in the competitive fitness of a second set of strains. These findings suggest that related strains of X. bovienii use xenorhabdicin and additional antagonistic molecules to compete against each other.
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Affiliation(s)
- Kristin Ciezki
- Department of Biological Sciences, University of Wisconsin, Milwaukee, WI 53211, USA
| | - Kristen Murfin
- Department of Bacteriology, University of Wisconsin, Madison, WI 53706, USA.,Department of Microbiology, Yale University, New Haven, CT 06519, USA
| | - Heidi Goodrich-Blair
- Department of Bacteriology, University of Wisconsin, Madison, WI 53706, USA.,Department of Microbiology, University of Tennessee-Knoxville, TN 37996, USA
| | - S Patricia Stock
- Department of Entomology, University of Arizona, Tucson, AZ 85721, USA
| | - Steven Forst
- Department of Biological Sciences, University of Wisconsin, Milwaukee, WI 53211, USA
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14
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Death Becomes Them: Bacterial Community Dynamics and Stilbene Antibiotic Production in Cadavers of Galleria mellonella Killed by Heterorhabditis and Photorhabdus spp. Appl Environ Microbiol 2016; 82:5824-37. [PMID: 27451445 DOI: 10.1128/aem.01211-16] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 07/14/2016] [Indexed: 12/19/2022] Open
Abstract
UNLABELLED Insect larvae killed by entomopathogenic nematodes are thought to contain bacterial communities dominated by a single bacterial genus, that of the nematode's bacterial symbiont. In this study, we used next-generation sequencing to profile bacterial community dynamics in greater wax moth (Galleria mellonella) larvae cadavers killed by Heterorhabditis nematodes and their Photorhabdus symbionts. We found that, although Photorhabdus strains did initially displace an Enterococcus-dominated community present in uninfected G. mellonella insect larvae, the cadaver community was not static. Twelve days postinfection, Photorhabdus shared the cadaver with Stenotrophomonas species. Consistent with this result, Stenotrophomonas strains isolated from infected cadavers were resistant to Photorhabdus-mediated toxicity in solid coculture assays. We isolated and characterized a Photorhabdus-produced antibiotic from G. mellonella cadavers, produced it synthetically, and demonstrated that both the natural and synthetic compounds decreased G. mellonella-associated Enterococcus growth, but not Stenotrophomonas growth, in vitro Finally, we showed that the Stenotrophomonas strains described here negatively affected Photorhabdus growth in vitro Our results add an important dimension to a broader understanding of Heterorhabditis-Photorhabdus biology and also demonstrate that interspecific bacterial competition likely characterizes even a theoretically monoxenic environment, such as a Heterorhabditis-Photorhabdus-parasitized insect cadaver. IMPORTANCE Understanding, and eventually manipulating, both human and environmental health depends on a complete accounting of the forces that act on and shape microbial communities. One of these underlying forces is hypothesized to be resource competition. A resource that has received little attention in the general microbiological literature, but likely has ecological and evolutionary importance, is dead/decaying multicellular organisms. Metazoan cadavers, including those of insects, are ephemeral and nutrient-rich environments, where resource competition might shape interspecific macrobiotic and microbiotic interactions. This study is the first to use a next-generation sequencing approach to study the community dynamics of bacteria within a model insect cadaver system: insect larvae parasitized by entomopathogenic nematodes and their bacterial symbionts. By integrating bioinformatic, biochemical, and classic in vitro microbiological approaches, we have provided mechanistic insight into how antibiotic-mediated bacterial interactions may shape community dynamics within insect cadavers.
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15
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Ketola T, Mikonranta L, Mappes J. Evolution of bacterial life-history traits is sensitive to community structure. Evolution 2016; 70:1334-41. [DOI: 10.1111/evo.12947] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 04/20/2016] [Accepted: 04/30/2016] [Indexed: 11/30/2022]
Affiliation(s)
- Tarmo Ketola
- Department of Biological and Environmental Science, Centre of Excellence in Biological Interactions; University of Jyvaskyla; P. O. Box 35 Jyväskylä 40014 Finland
| | - Lauri Mikonranta
- Department of Biological and Environmental Science, Centre of Excellence in Biological Interactions; University of Jyvaskyla; P. O. Box 35 Jyväskylä 40014 Finland
| | - Johanna Mappes
- Department of Biological and Environmental Science, Centre of Excellence in Biological Interactions; University of Jyvaskyla; P. O. Box 35 Jyväskylä 40014 Finland
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16
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Abstract
Be it their pervasiveness, experimental tractability or their impact on human health and agriculture, nematode–bacterium associations are far-reaching research subjects. Although the omics hype did not spare them and helped reveal mechanisms of communication and exchange between the associated partners, a huge amount of knowledge still awaits to be harvested from their study. Here, I summarize and compare the kind of research that has been already performed on the model nematode Caenorhabditis elegans and on symbiotic nematodes, both marine and entomopathogenic ones. The emerging picture highlights how complementing genetic studies with ecological ones (in the case of well-established genetic model systems such as C. elegans) and vice versa (in the case of the yet uncultured Stilbonematinae) will deepen our understanding of how microbial symbioses evolved and how they impact our environment. Nematode–bacterium associations are major research subjects. Complementing genetic studies with ecological ones is necessary to boost our understanding of how microbial symbioses evolved and how they impact the environment.
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Affiliation(s)
- Silvia Bulgheresi
- Department of Ecogenomics and Systems Biology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
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17
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Tollenaere C, Susi H, Laine AL. Evolutionary and Epidemiological Implications of Multiple Infection in Plants. TRENDS IN PLANT SCIENCE 2016; 21:80-90. [PMID: 26651920 DOI: 10.1016/j.tplants.2015.10.014] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 10/02/2015] [Accepted: 10/20/2015] [Indexed: 05/04/2023]
Abstract
Recent methodological advances have uncovered tremendous microbial diversity cohabiting in the same host plant, and many of these microbes cause disease. In this review we highlight how the presence of other pathogen species, or other pathogen genotypes, within a plant can affect key components of host-pathogen interactions: (i) within-plant virulence and pathogen accumulation, through direct and host-mediated mechanisms; (ii) evolutionary trajectories of pathogen populations, through virulence evolution, generation of novel genetic combinations, and maintenance of genetic diversity; and (iii) disease dynamics, with multiple infection likely to render epidemics more devastating. The major future challenges are to couple a community ecology approach with a molecular investigation of the mechanisms operating under coinfection and to evaluate the evolution and effectiveness of resistance within a coinfection framework.
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Affiliation(s)
- Charlotte Tollenaere
- Interactions Plantes-Microorganismes et Environnement (IPME), Institut de Recherches pour le Développement (IRD) - Cirad - Université de Montpellier, 34394 Montpellier, France; Laboratoire Mixte International Patho-Bios, IRD-INERA (Institut de l'Environnement et de Recherches Agricoles), BP171, Bobo-Dioulasso, Burkina Faso
| | - Hanna Susi
- Metapopulation Research Centre, Department of Biosciences, PO Box 65 (Viikinkaari 1), FI-00014 University of Helsinki, Helsinki, Finland
| | - Anna-Liisa Laine
- Metapopulation Research Centre, Department of Biosciences, PO Box 65 (Viikinkaari 1), FI-00014 University of Helsinki, Helsinki, Finland.
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18
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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.
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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
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19
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Abstract
Why is it that some parasites cause high levels of host damage (i.e. virulence) whereas others are relatively benign? There are now numerous reviews of virulence evolution in the literature but it is nevertheless still difficult to find a comprehensive treatment of the theory and data on the subject that is easily accessible to non-specialists. Here we attempt to do so by distilling the vast theoretical literature on the topic into a set of relatively few robust predictions. We then provide a comprehensive assessment of the available empirical literature that tests these predictions. Our results show that there have been some notable successes in integrating theory and data but also that theory and empiricism in this field do not ‘speak’ to each other very well. We offer a few suggestions for how the connection between the two might be improved.
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20
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Bashey F. Within-host competitive interactions as a mechanism for the maintenance of parasite diversity. Philos Trans R Soc Lond B Biol Sci 2015; 370:20140301. [PMID: 26150667 PMCID: PMC4528499 DOI: 10.1098/rstb.2014.0301] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/14/2015] [Indexed: 12/11/2022] Open
Abstract
Variation among parasite strains can affect the progression of disease or the effectiveness of treatment. What maintains parasite diversity? Here I argue that competition among parasites within the host is a major cause of variation among parasites. The competitive environment within the host can vary depending on the parasite genotypes present. For example, parasite strategies that target specific competitors, such as bacteriocins, are dependent on the presence and susceptibility of those competitors for success. Accordingly, which parasite traits are favoured by within-host selection can vary from host to host. Given the fluctuating fitness landscape across hosts, genotype by genotype (G×G) interactions among parasites should be prevalent. Moreover, selection should vary in a frequency-dependent manner, as attacking genotypes select for resistance and genotypes producing public goods select for cheaters. I review competitive coexistence theory with regard to parasites and highlight a few key examples where within-host competition promotes diversity. Finally, I discuss how within-host competition affects host health and our ability to successfully treat infectious diseases.
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Affiliation(s)
- Farrah Bashey
- Department of Biology, Indiana University, 1001 East Third Street, Bloomington, IN 47405, USA
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21
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Buono L, López-Villavicencio M, Shykoff JA, Snirc A, Giraud T. Influence of multiple infection and relatedness on virulence: disease dynamics in an experimental plant population and its castrating parasite. PLoS One 2014; 9:e98526. [PMID: 24892951 PMCID: PMC4043691 DOI: 10.1371/journal.pone.0098526] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 05/02/2014] [Indexed: 11/18/2022] Open
Abstract
The level of parasite virulence, i.e., the decrease in host's fitness due to a pathogen, is expected to depend on several parameters, such as the type of the disease (e.g., castrating or host-killing) and the prevalence of multiple infections. Although these parameters have been extensively studied theoretically, few empirical data are available to validate theoretical predictions. Using the anther smut castrating disease on Silene latifolia caused by Microbotryum lychnidis-dioicae, we studied the dynamics of multiple infections and of different components of virulence (host death, non-recovery and percentage of castrated stems) during the entire lifespan of the host in an experimental population. We monitored the number of fungal genotypes within plants and their relatedness across five years, using microsatellite markers, as well as the rates of recovery and host death in the population. The mean relatedness among genotypes within plants remained at a high level throughout the entire host lifespan despite the dynamics of the disease, with recurrent new infections. Recovery was lower for plants with multiple infections compared to plants infected by a single genotype. As expected for castrating parasites, M. lychnidis-dioicae did not increase host mortality. Mortality varied across years but was generally lower for plants that had been diseased the preceding year. This is one of the few studies to have empirically verified theoretical expectations for castrating parasites, and to show particularly i) that castrated hosts live longer, suggesting that parasites can redirect resources normally used in reproduction to increase host lifespan, lengthening their transmission phase, and ii) that multiple infections increase virulence, here in terms of non-recovery and host castration.
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Affiliation(s)
- Lorenza Buono
- Ecologie, Systématique et Evolution, Université Paris-Sud, Orsay, France
- Ecologie, Systématique et Evolution, CNRS, Orsay, France
| | - Manuela López-Villavicencio
- Department Systématique et Evolution, Origine, Structure, Evolution de la Biodiversité, UMR 7205 CNRS-MNHN, Muséum National d'Histoire Naturelle, Paris, France
| | - Jacqui A. Shykoff
- Ecologie, Systématique et Evolution, Université Paris-Sud, Orsay, France
- Ecologie, Systématique et Evolution, CNRS, Orsay, France
| | - Alodie Snirc
- Ecologie, Systématique et Evolution, Université Paris-Sud, Orsay, France
- Ecologie, Systématique et Evolution, CNRS, Orsay, France
| | - Tatiana Giraud
- Ecologie, Systématique et Evolution, Université Paris-Sud, Orsay, France
- Ecologie, Systématique et Evolution, CNRS, Orsay, France
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22
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Abstract
Parasite virulence, or the damage a parasite does to its host, is measured in terms of both host costs (reductions in host growth, reproduction and survival) and parasite benefits (increased transmission and parasite numbers) in the literature. Much work has shown that ecological and genetic factors can be strong selective forces in virulence evolution. This review uses kin selection theory to explore how variations in host ecological parameters impact the genetic relatedness of parasite populations and thus virulence. We provide a broad overview of virulence and population genetics studies and then draw connections to existing knowledge about natural parasite populations. The impact of host movement (transporting parasites) and host resistance (filtering parasites) on the genetic structure and virulence of parasite populations is explored, and empirical studies of these factors using Plasmodium and trematode systems are proposed.
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23
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Werner GDA, Strassmann JE, Ivens ABF, Engelmoer DJP, Verbruggen E, Queller DC, Noë R, Johnson NC, Hammerstein P, Kiers ET. Evolution of microbial markets. Proc Natl Acad Sci U S A 2014; 111:1237-44. [PMID: 24474743 PMCID: PMC3910570 DOI: 10.1073/pnas.1315980111] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Biological market theory has been used successfully to explain cooperative behavior in many animal species. Microbes also engage in cooperative behaviors, both with hosts and other microbes, that can be described in economic terms. However, a market approach is not traditionally used to analyze these interactions. Here, we extend the biological market framework to ask whether this theory is of use to evolutionary biologists studying microbes. We consider six economic strategies used by microbes to optimize their success in markets. We argue that an economic market framework is a useful tool to generate specific and interesting predictions about microbial interactions, including the evolution of partner discrimination, hoarding strategies, specialized versus diversified mutualistic services, and the role of spatial structures, such as flocks and consortia. There is untapped potential for studying the evolutionary dynamics of microbial systems. Market theory can help structure this potential by characterizing strategic investment of microbes across a diversity of conditions.
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Affiliation(s)
- Gijsbert D. A. Werner
- Department of Ecological Science, Vrije Universiteit Amsterdam, 1081 HV, Amsterdam, The Netherlands
| | - Joan E. Strassmann
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130
| | - Aniek B. F. Ivens
- Theoretical Biology Group, Centre for Ecological and Evolutionary Studies, University of Groningen, 9700 CC, Groningen, The Netherlands
- Laboratory of Insect Social Evolution, The Rockefeller University, New York, NY 10065
| | - Daniel J. P. Engelmoer
- Department of Ecological Science, Vrije Universiteit Amsterdam, 1081 HV, Amsterdam, The Netherlands
| | - Erik Verbruggen
- Institut für Biologie, Plant Ecology, Freie Universität Berlin, 14195 Berlin, Germany
| | - David C. Queller
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130
| | - Ronald Noë
- Faculté de Psychologie, Université de Strasbourg et Ethologie Evolutive, Département Ecologie, Physiologie et Ethologie, Centre National de la Recherche Scientifique, 67087 Strasbourg Cedex, France
- Netherlands Institute of Advanced Studies, 2242 PR, Wassenaar, The Netherlands
| | - Nancy Collins Johnson
- School of Earth Sciences and Environmental Sustainability and Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011-5694; and
| | - Peter Hammerstein
- Institute for Theoretical Biology, Humboldt University, 10115 Berlin, Germany
| | - E. Toby Kiers
- Department of Ecological Science, Vrije Universiteit Amsterdam, 1081 HV, Amsterdam, The Netherlands
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24
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Bashey F, Hawlena H, Lively CM. Alternative paths to success in a parasite community: within-host competition can favor higher virulence or direct interference. Evolution 2012; 67:900-7. [PMID: 23461339 DOI: 10.1111/j.1558-5646.2012.01825.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Selection imposed by coinfection may vary with the mechanism of within-host competition between parasites. Exploitative competition is predicted to favor more virulent parasites, whereas interference competition may result in lower virulence. Here, we examine whether exploitative or interference competition determines the outcome of competition between two nematode species (Steinernema spp.), which in combination with their bacterial symbionts (Xenorhabdus spp.), infect and kill insect hosts. Multiple isolates of each nematode species, carrying their naturally associated bacteria, were characterized by (1) the rate at which they killed insect hosts, and by (2) the ability of their bacteria to interfere with each other's growth via bacteriocidal toxins called "bacteriocins." We found that both exploitative and interference abilities were important in predicting which species had a selective advantage in pairwise competition experiments. When nematodes carried bacteria that did not interact via bacteriocins, the faster killing isolate had a competitive advantage. Alternatively, nematodes could gain a competitive advantage when they carried bacteria able to inhibit the bacteria of their competitor. Thus, the combination of nematode/bacterial traits that led to competitive success depended on which isolates were paired, suggesting that variation in competitive interactions may be important for maintaining species diversity in this community.
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Affiliation(s)
- Farrah Bashey
- Department of Biology, Indiana University, Bloomington, Indiana 47405-3700, USA.
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25
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Hawlena H, Bashey F, Lively CM. Bacteriocin-mediated interactions within and between coexisting species. Ecol Evol 2012; 2:2521-6. [PMID: 23145336 PMCID: PMC3492777 DOI: 10.1002/ece3.354] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 07/15/2012] [Accepted: 07/22/2012] [Indexed: 12/27/2022] Open
Abstract
Bacteriocins are bacteriocidal toxins released by almost all bacteria. They are thought to have a narrow range of killing, but as bacteriocin-mediated interactions have been rarely studied at biologically relevant scales, whether this narrow range of action falls mostly within or mostly between coexisting species in natural communities is an open question with important ecological and evolutionary implications. In a previous study, we systematically sampled Xenorhabdus bacteria along a hillside and found evidence for genotypic variability and bacteriocin-mediated interactions within Xenorhabdus bovienii and X. koppenhoeferi colonies that were collected only a few meters apart. In contrast, colonies that were isolated from the same soil sample were always genetically similar and showed no inhibitions. Here, we conducted pairwise growth-inhibition assays within and between seven X. bovienii and five X. koppenhoeferi colonies that were isolated from different soil samples; all seven X. bovienii colonies and at least three of the X. koppenhoeferi have been distinguished as distinct genotypes based on coarse-grain genomic markers. We found signatures for both conspecific and heterospecific bacteriocin inhibitions in this natural community of Xenorhabdus bacteria, but intraspecific inhibitions were significantly more common than interspecific inhibitions. These results suggest that bacteriocins have a major role in intraspecific competition in nature, but also suggest that bacterocins are important in mediating interspecific interactions among coexisting species in natural communities.
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Affiliation(s)
- Hadas Hawlena
- Department of Life Sciences, Ben Gurion University of the NegevBeer-Sheva, 84105, Israel
| | - Farrah Bashey
- Department of Biology, Indiana UniversityBloomington, Indiana, 47405-3700, USA
| | - Curtis M Lively
- Department of Biology, Indiana UniversityBloomington, Indiana, 47405-3700, USA
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26
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Murfin KE, Dillman AR, Foster JM, Bulgheresi S, Slatko BE, Sternberg PW, Goodrich-Blair H. Nematode-bacterium symbioses--cooperation and conflict revealed in the "omics" age. THE BIOLOGICAL BULLETIN 2012; 223:85-102. [PMID: 22983035 PMCID: PMC3508788 DOI: 10.1086/bblv223n1p85] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Nematodes are ubiquitous organisms that have a significant global impact on ecosystems, economies, agriculture, and human health. The applied importance of nematodes and the experimental tractability of many species have promoted their use as models in various research areas, including developmental biology, evolutionary biology, ecology, and animal-bacterium interactions. Nematodes are particularly well suited for the investigation of host associations with bacteria because all nematodes have interacted with bacteria during their evolutionary history and engage in a variety of association types. Interactions between nematodes and bacteria can be positive (mutualistic) or negative (pathogenic/parasitic) and may be transient or stably maintained (symbiotic). Furthermore, since many mechanistic aspects of nematode-bacterium interactions are conserved, their study can provide broader insights into other types of associations, including those relevant to human diseases. Recently, genome-scale studies have been applied to diverse nematode-bacterial interactions and have helped reveal mechanisms of communication and exchange between the associated partners. In addition to providing specific information about the system under investigation, these studies also have helped inform our understanding of genome evolution, mutualism, and innate immunity. In this review we discuss the importance and diversity of nematodes, "omics"' studies in nematode-bacterial systems, and the wider implications of the findings.
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Affiliation(s)
- Kristen E. Murfin
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706
| | - Adler R. Dillman
- HHMI and Division of Biology, California Institute of Technology, 156-29, Pasadena, CA 91125, USA
| | - Jeremy M. Foster
- Parasitology Division, New England Biolabs, Inc., 240 County Rd, Ipswich, MA 01938, USA
| | - Silvia Bulgheresi
- Department of Genetics in Ecology, University of Vienna, Vienna, Austria
| | - Barton E. Slatko
- Parasitology Division, New England Biolabs, Inc., 240 County Rd, Ipswich, MA 01938, USA
| | - Paul W. Sternberg
- HHMI and Division of Biology, California Institute of Technology, 156-29, Pasadena, CA 91125, USA
| | - Heidi Goodrich-Blair
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706
- Corresponding author Department of Bacteriology, University of Wisconsin-Madison, 1550 Linden Dr., Madison, WI 53706, , phone: 608-265-4537, fax: 608-262-9865
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27
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Inglis RF, Brown SP, Buckling A. Spite versus cheats: competition among social strategies shapes virulence in Pseudomonas aeruginosa. Evolution 2012; 66:3472-84. [PMID: 23106711 PMCID: PMC3795443 DOI: 10.1111/j.1558-5646.2012.01706.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Social interactions have been shown to play an important role in bacterial evolution and virulence. The majority of empirical studies conducted have only considered social traits in isolation, yet numerous social traits, such as the production of spiteful bacteriocins (anticompetitor toxins) and iron-scavenging siderophores (a public good) by the opportunistic pathogen Pseudomonas aeruginosa, are frequently expressed simultaneously. Crucially, both bacteriocin production and siderophore cheating can be favored under the same competitive conditions, and we develop theory and carry out experiments to determine how the success of a bacteriocin-producing genotype is influenced by social cheating of susceptible competitors and the resultant impact on disease severity (virulence). Consistent with our theoretical predictions, we find that the spiteful genotype is favored at higher local frequencies when competing against public good cheats. Furthermore, the relationship between spite frequency and virulence is significantly altered when the spiteful genotype is competed against cheats compared with cooperators. These results confirm the ecological and evolutionary importance of considering multiple social traits simultaneously. Moreover, our results are consistent with recent theory regarding the invasion conditions for strong reciprocity (helping cooperators and harming noncooperators).
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Affiliation(s)
- R Fredrik Inglis
- Department of Zoology, University of Oxford, Oxford, OX1 3PS, United Kingdom.
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Cory JS, Franklin MT. Evolution and the microbial control of insects. Evol Appl 2012; 5:455-69. [PMID: 22949921 PMCID: PMC3407864 DOI: 10.1111/j.1752-4571.2012.00269.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 04/24/2012] [Indexed: 11/26/2022] Open
Abstract
Insect pathogens can be utilized in a variety of pest management approaches, from inundative release to augmentation and classical biological control, and microevolution and the consideration of evolutionary principles can potentially influence the success of all these strategies. Considerable diversity exists in natural entomopathogen populations and this diversity can be either beneficial or detrimental for pest suppression, depending on the pathogen and its mode of competition, and this should be considered in the selection of isolates for biological control. Target hosts can exhibit considerable variation in their susceptibility to entomopathogens, and cases of field-evolved resistance have been documented for Bacillus thuringiensis and baculoviruses. Strong selection, limited pathogen diversity, reduced gene flow, and host plant chemistry are linked to cases of resistance and should be considered when developing resistance management strategies. Pre- and post-release monitoring of microbial control programs have received little attention; however, to date there have been no reports of host-range evolution or long-term negative effects on nontarget hosts. Comparative analyses of pathogen population structure, virulence, and host resistance over time are required to elucidate the evolutionary dynamics of microbial control systems.
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Affiliation(s)
- Jenny S Cory
- Department of Biological Sciences, Simon Fraser UniversityBurnaby, BC, Canada
- * Correspondence Jenny S. Cory, Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada. Tel.: 17787825714; fax: 17787823496; e-mail:
| | - Michelle T Franklin
- Department of Biological Sciences, Simon Fraser UniversityBurnaby, BC, Canada
- Department of Zoology, University of British ColumbiaVancouver, BC, Canada
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