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Zhou SO, Arunkumar R, Irfan A, Ding SD, Leitão AB, Jiggins FM. The evolution of constitutively active humoral immune defenses in Drosophila populations under high parasite pressure. PLoS Pathog 2024; 20:e1011729. [PMID: 38206983 PMCID: PMC10807768 DOI: 10.1371/journal.ppat.1011729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 01/24/2024] [Accepted: 01/04/2024] [Indexed: 01/13/2024] Open
Abstract
Both constitutive and inducible immune mechanisms are employed by hosts for defense against infection. Constitutive immunity allows for a faster response, but it comes with an associated cost that is always present. This trade-off between speed and fitness costs leads to the theoretical prediction that constitutive immunity will be favored where parasite exposure is frequent. We selected populations of Drosophila melanogaster under high parasite pressure from the parasitoid wasp Leptopilina boulardi. With RNA sequencing, we found the evolution of resistance in these populations was associated with them developing constitutively active humoral immunity, mediated by the larval fat body. Furthermore, these evolved populations were also able to induce gene expression in response to infection to a greater level, which indicates an overall more activated humoral immune response to parasitization. The anti-parasitoid immune response also relies on the JAK/STAT signaling pathway being activated in muscles following infection, and this induced response was only seen in populations that had evolved under high parasite pressure. We found that the cytokine Upd3, which induces this JAK/STAT response, is being expressed by immature lamellocytes. Furthermore, these immune cells became constitutively present when populations evolved resistance, potentially explaining why they gained the ability to activate JAK/STAT signaling. Thus, under intense parasitism, populations evolved resistance by increasing both constitutive and induced immune defenses, and there is likely an interplay between these two forms of immunity.
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Affiliation(s)
- Shuyu Olivia Zhou
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Ramesh Arunkumar
- Section of population genetics, School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Amina Irfan
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | | | - Alexandre B. Leitão
- Champalimaud Foundation, Champalimaud Centre of the Unknown, Lisbon, Portugal
| | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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2
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Critchlow JT, Prakash A, Zhong KY, Tate AT. Mapping the functional form of the trade-off between infection resistance and reproductive fitness under dysregulated immune signaling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.10.552815. [PMID: 37645726 PMCID: PMC10461925 DOI: 10.1101/2023.08.10.552815] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Immune responses benefit organismal fitness by clearing parasites but also exact costs associated with immunopathology and energetic investment. Hosts manage these costs by tightly regulating the induction of immune signaling to curtail excessive responses and restore homeostasis. Despite the theoretical importance of turning off the immune response to mitigate these costs, experimentally connecting variation in the negative regulation of immune responses to organismal fitness remains a frontier in evolutionary immunology. In this study, we used a dose-response approach to manipulate the RNAi-mediated knockdown efficiency of cactus (IκBα), a central regulator of Toll pathway signal transduction in flour beetles (Tribolium castaneum). By titrating cactus activity along a continuous gradient, we derived the shape of the relationship between immune response investment and traits associated with host fitness, including infection susceptibility, lifespan, fecundity, body mass, and gut homeostasis. Cactus knock-down increased the overall magintude of inducible immune responses and delayed their resolution in a dsRNA dose-dependent manner, promoting survival and resistance following bacterial infection. However, these benefits were counterbalanced by dsRNA dose-dependent costs to lifespan, fecundity, body mass, and gut integrity. Our results allowed us to move beyond the qualitative identification of a trade-off between immune investment and fitness to actually derive its functional form. This approach paves the way to quantitatively compare the evolution and impact of distinct regulatory elements on life-history trade-offs and fitness, filling a crucial gap in our conceptual and theoretical models of immune signaling network evolution and the maintenance of natural variation in immune systems.
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Affiliation(s)
- Justin T. Critchlow
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Arun Prakash
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Katherine Y. Zhong
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Ann T. Tate
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Evolutionary Studies Institute, Vanderbilt University, Nashville, Tennessee, United States of America
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3
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Hagen EH, Blackwell AD, Lightner AD, Sullivan RJ. Homo medicus: The transition to meat eating increased pathogen pressure and the use of pharmacological plants in Homo. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2023; 180:589-617. [PMID: 36815505 DOI: 10.1002/ajpa.24718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 01/31/2023] [Accepted: 02/08/2023] [Indexed: 02/24/2023]
Abstract
The human lineage transitioned to a more carnivorous niche 2.6 mya and evolved a large body size and slower life history, which likely increased zoonotic pathogen pressure. Evidence for this increase includes increased zoonotic infections in modern hunter-gatherers and bushmeat hunters, exceptionally low stomach pH compared to other primates, and divergence in immune-related genes. These all point to change, and probably intensification, in the infectious disease environment of Homo compared to earlier hominins and other apes. At the same time, the brain, an organ in which immune responses are constrained, began to triple in size. We propose that the combination of increased zoonotic pathogen pressure and the challenges of defending a large brain and body from pathogens in a long-lived mammal, selected for intensification of the plant-based self-medication strategies already in place in apes and other primates. In support, there is evidence of medicinal plant use by hominins in the middle Paleolithic, and all cultures today have sophisticated, plant-based medical systems, add spices to food, and regularly consume psychoactive plant substances that are harmful to helminths and other pathogens. We propose that the computational challenges of discovering effective plant-based treatments, the consequent ability to consume more energy-rich animal foods, and the reduced reliance on energetically-costly immune responses helped select for increased cognitive abilities and unique exchange relationships in Homo. In the story of human evolution, which has long emphasized hunting skills, medical skills had an equal role to play.
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Affiliation(s)
- Edward H Hagen
- Department of Anthropology, Washington State University, Pullman, Washington, USA
| | - Aaron D Blackwell
- Department of Anthropology, Washington State University, Pullman, Washington, USA
| | - Aaron D Lightner
- Department of Anthropology, Washington State University, Pullman, Washington, USA
- Department of the Study of Religion, Aarhus University, Aarhus, Denmark
| | - Roger J Sullivan
- Department of Anthropology, California State University, Sacramento, California, USA
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4
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Martin RA, Tate AT. Pleiotropy promotes the evolution of inducible immune responses in a model of host-pathogen coevolution. PLoS Comput Biol 2023; 19:e1010445. [PMID: 37022993 PMCID: PMC10079112 DOI: 10.1371/journal.pcbi.1010445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 02/23/2023] [Indexed: 04/07/2023] Open
Abstract
Components of immune systems face significant selective pressure to efficiently use organismal resources, mitigate infection, and resist parasitic manipulation. A theoretically optimal immune defense balances investment in constitutive and inducible immune components depending on the kinds of parasites encountered, but genetic and dynamic constraints can force deviation away from theoretical optima. One such potential constraint is pleiotropy, the phenomenon where a single gene affects multiple phenotypes. Although pleiotropy can prevent or dramatically slow adaptive evolution, it is prevalent in the signaling networks that compose metazoan immune systems. We hypothesized that pleiotropy is maintained in immune signaling networks despite slowed adaptive evolution because it provides some other advantage, such as forcing network evolution to compensate in ways that increase host fitness during infection. To study the effects of pleiotropy on the evolution of immune signaling networks, we used an agent-based modeling approach to evolve a population of host immune systems infected by simultaneously co-evolving parasites. Four kinds of pleiotropic restrictions on evolvability were incorporated into the networks, and their evolutionary outcomes were compared to, and competed against, non-pleiotropic networks. As the networks evolved, we tracked several metrics of immune network complexity, relative investment in inducible and constitutive defenses, and features associated with the winners and losers of competitive simulations. Our results suggest non-pleiotropic networks evolve to deploy highly constitutive immune responses regardless of parasite prevalence, but some implementations of pleiotropy favor the evolution of highly inducible immunity. These inducible pleiotropic networks are no less fit than non-pleiotropic networks and can out-compete non-pleiotropic networks in competitive simulations. These provide a theoretical explanation for the prevalence of pleiotropic genes in immune systems and highlight a mechanism that could facilitate the evolution of inducible immune responses.
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Affiliation(s)
- Reese A. Martin
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Evolutionary Studies Initiative, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Ann T. Tate
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Evolutionary Studies Initiative, Vanderbilt University, Nashville, Tennessee, United States of America
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5
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Mucin induces CRISPR-Cas defense in an opportunistic pathogen. Nat Commun 2022; 13:3653. [PMID: 35752617 PMCID: PMC9233685 DOI: 10.1038/s41467-022-31330-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 06/14/2022] [Indexed: 01/21/2023] Open
Abstract
Parasitism by bacteriophages has led to the evolution of a variety of defense mechanisms in their host bacteria. However, it is unclear what factors lead to specific defenses being deployed upon phage infection. To explore this question, we co-evolved the bacterial fish pathogen Flavobacterium columnare and its virulent phage V156 in presence and absence of a eukaryotic host signal (mucin) for sixteen weeks. The presence of mucin leads to a dramatic increase in CRISPR spacer acquisition, especially in low nutrient conditions where over 60% of colonies obtain at least one new spacer. Additionally, we show that the presence of a competitor bacterium further increases CRISPR spacer acquisition in F. columnare. These results suggest that ecological factors are important in determining defense strategies against phages, and that the phage-bacterium interactions on mucosal surfaces may select for the diversification of bacterial immune systems. It is unknown what circumstances promote particular bacterial defenses against bacterial viruses (phages). Almeida & Hoikkala et al. show that mucin, derived from mucus, greatly accelerates CRISPR-Cas defenses against phage in an opportunistic pathogen.
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6
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de Freitas Almeida GM, Hoikkala V, Ravantti J, Rantanen N, Sundberg LR. Mucin induces CRISPR-Cas defense in an opportunistic pathogen. Nat Commun 2022; 13:3653. [PMID: 35752617 DOI: 10.1101/2021.08.10.455787v1.abstract] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 06/14/2022] [Indexed: 05/27/2023] Open
Abstract
Parasitism by bacteriophages has led to the evolution of a variety of defense mechanisms in their host bacteria. However, it is unclear what factors lead to specific defenses being deployed upon phage infection. To explore this question, we co-evolved the bacterial fish pathogen Flavobacterium columnare and its virulent phage V156 in presence and absence of a eukaryotic host signal (mucin) for sixteen weeks. The presence of mucin leads to a dramatic increase in CRISPR spacer acquisition, especially in low nutrient conditions where over 60% of colonies obtain at least one new spacer. Additionally, we show that the presence of a competitor bacterium further increases CRISPR spacer acquisition in F. columnare. These results suggest that ecological factors are important in determining defense strategies against phages, and that the phage-bacterium interactions on mucosal surfaces may select for the diversification of bacterial immune systems.
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Affiliation(s)
- Gabriel Magno de Freitas Almeida
- University of Jyväskylä, Department of Biological and Environmental Science and Nanoscience Center, Jyväskylä, Finland
- Faculty of Biosciences, Fisheries and Economics, Norwegian College of Fishery Science, UiT The Arctic University of Norway, Tromsø, Norway
| | - Ville Hoikkala
- University of Jyväskylä, Department of Biological and Environmental Science and Nanoscience Center, Jyväskylä, Finland
| | - Janne Ravantti
- University of Helsinki, Molecular and Integrative Biosciences Research Programme, Helsinki, Finland
| | - Noora Rantanen
- University of Jyväskylä, Department of Biological and Environmental Science and Nanoscience Center, Jyväskylä, Finland
| | - Lotta-Riina Sundberg
- University of Jyväskylä, Department of Biological and Environmental Science and Nanoscience Center, Jyväskylä, Finland.
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7
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Tate AT, Schulz NK. The within-host ecology of insects and their parasites: integrating experiments and mathematical models. CURRENT OPINION IN INSECT SCIENCE 2022; 49:37-41. [PMID: 34793990 DOI: 10.1016/j.cois.2021.11.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 11/03/2021] [Accepted: 11/11/2021] [Indexed: 06/13/2023]
Abstract
The within-host ecology of hosts and their microbes involves complex feedbacks between the host immune system, energetic resources, and microbial growth and virulence, which in turn affect the probability of transmission to new hosts. This complexity can be challenging to address with experiments alone, and mathematical models have traditionally played an essential role in disentangling these processes, making new predictions, and bridging gaps across biological scales. Insect hosts serve as uniquely powerful systems for the integration of experiments and theory in disease biology. In this review, we highlight recent studies in fruit flies, moths, beetles and other invertebrates that have inspired important mathematical models, and present open questions arising from recent modeling efforts that are ripe for testing in insects.
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Affiliation(s)
- Ann T Tate
- Department of Biological Sciences, Vanderbilt University, 465 21(st) Ave S., Nashville, TN, USA.
| | - Nora Ke Schulz
- Department of Biological Sciences, Vanderbilt University, 465 21(st) Ave S., Nashville, TN, USA
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8
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Downie AE, Mayer A, Metcalf CJE, Graham AL. Optimal immune specificity at the intersection of host life history and parasite epidemiology. PLoS Comput Biol 2021; 17:e1009714. [PMID: 34932551 PMCID: PMC8730424 DOI: 10.1371/journal.pcbi.1009714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 01/05/2022] [Accepted: 12/02/2021] [Indexed: 11/30/2022] Open
Abstract
Hosts diverge widely in how, and how well, they defend themselves against infection and immunopathology. Why are hosts so heterogeneous? Both epidemiology and life history are commonly hypothesized to influence host immune strategy, but the relationship between immune strategy and each factor has commonly been investigated in isolation. Here, we show that interactions between life history and epidemiology are crucial for determining optimal immune specificity and sensitivity. We propose a demographically-structured population dynamics model, in which we explore sensitivity and specificity of immune responses when epidemiological risks vary with age. We find that variation in life history traits associated with both reproduction and longevity alters optimal immune strategies-but the magnitude and sometimes even direction of these effects depends on how epidemiological risks vary across life. An especially compelling example that explains previously-puzzling empirical observations is that depending on whether infection risk declines or rises at reproductive maturity, later reproductive maturity can select for either greater or lower immune specificity, potentially illustrating why studies of lifespan and immune variation across taxa have been inconclusive. Thus, the sign of selection on the life history-immune specificity relationship can be reversed in different epidemiological contexts. Drawing on published life history data from a variety of chordate taxa, we generate testable predictions for this facet of the optimal immune strategy. Our results shed light on the causes of the heterogeneity found in immune defenses both within and among species and the ultimate variability of the relationship between life history and immune specificity.
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Affiliation(s)
- Alexander E. Downie
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Andreas Mayer
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
| | - C. Jessica E. Metcalf
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
- School of Public and International Affairs, Princeton University, Princeton, New Jersey, United States of America
| | - Andrea L. Graham
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
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9
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Eskew EA, Fraser D, Vonhof MJ, Pinsky ML, Maslo B. Host gene expression in wildlife disease: making sense of species-level responses. Mol Ecol 2021; 30:6517-6530. [PMID: 34516689 DOI: 10.1111/mec.16172] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 08/16/2021] [Accepted: 08/31/2021] [Indexed: 12/11/2022]
Abstract
Emerging infectious diseases are significant threats to wildlife conservation, yet the impacts of pathogen exposure and infection can vary widely among host species. As such, conservation biologists and disease ecologists have increasingly aimed to understand species-specific host susceptibility using molecular methods. In particular, comparative gene expression assays have been used to contrast the transcriptomic responses of disease-resistant and disease-susceptible hosts to pathogen exposure. This work usually assumes that the gene expression responses of disease-resistant species will reveal the activation of molecular pathways contributing to host defence. However, results often show that disease-resistant hosts undergo little gene expression change following pathogen challenge. Here, we discuss the mechanistic implications of these "null" findings and offer methodological suggestions for future molecular studies of wildlife disease. First, we highlight that muted transcriptomic responses with minimal immune system recruitment may indeed be protective for nonsusceptible hosts if they limit immunopathology and promote pathogen tolerance in systems where susceptible hosts suffer from genetic dysregulation. Second, we argue that overly narrow investigation of responses to pathogen exposure may overlook important, constitutively active molecular pathways that underlie species-specific defences. Finally, we outline alternative study designs and approaches that complement interspecific transcriptomic comparisons, including intraspecific gene expression studies and genomic methods to detect signatures of selection. Collectively, these insights will help ecologists extract maximal information from conservation-relevant transcriptomic data sets, leading to a deeper understanding of host defences and, ultimately, the implementation of successful conservation interventions.
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Affiliation(s)
- Evan A Eskew
- Department of Ecology, Evolution and Natural Resources, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, USA.,Department of Biology, Pacific Lutheran University, Tacoma, Washington, USA
| | - Devaughn Fraser
- Wildlife Genetics Research Laboratory, California Department of Fish and Wildlife, Sacramento, California, USA
| | - Maarten J Vonhof
- Department of Biological Sciences, Western Michigan University, Kalamazoo, Michigan, USA
| | - Malin L Pinsky
- Department of Ecology, Evolution and Natural Resources, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, USA
| | - Brooke Maslo
- Department of Ecology, Evolution and Natural Resources, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, USA
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10
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Paddock KJ, Pereira AE, Finke DL, Ericsson AC, Hibbard BE, Shelby KS. Host resistance to Bacillus thuringiensis is linked to altered bacterial community within a specialist insect herbivore. Mol Ecol 2021; 30:5438-5453. [PMID: 33683750 PMCID: PMC9290792 DOI: 10.1111/mec.15875] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 02/12/2021] [Accepted: 03/01/2021] [Indexed: 12/19/2022]
Abstract
Evolution of resistance to transgenic crops producing toxins from Bacillus thuringiensis (Bt) threatens the sustainability of the technology. Examination of resistance mechanisms has largely focused on characterization of mutations in proteins serving as Bt toxin binding sites. However, insect microbial communities have the potential to provide host resistance to pesticides in a myriad of ways. Previous findings suggest the killing mechanism of Bt relies on enteric bacteria becoming pathogenic in the disrupted gut environment of the insect following Bt intoxication. Thus, here we hypothesized that resistance to Bt would alter the microbiome composition of the insect. Previous studies have manipulated the microbiome of susceptible insects and monitored their response to Bt. In our study, we characterized the associated bacterial communities of Bt‐resistant and ‐susceptible western corn rootworms, a widespread pest of maize in the United States. We found resistant insects harbor a bacterial community that is less rich and distinct from susceptible insects. After feeding on Bt‐expressing maize, susceptible insects exhibited dysbiosis of the associated bacterial community, whereas the community within resistant insects remained relatively unchanged. These results suggest resistance to Bt produces alterations in the microbiome of the western corn rootworm that may contribute to resistance. We further demonstrated that by itself, feeding on Bt toxin‐expressing seedlings caused a shift in the microbiota. This work provides a broader picture of the effect stressors have on microbiome composition, and the potential heritable changes induced as a result of intense selection.
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Affiliation(s)
- Kyle J Paddock
- Division of Plant Sciences, University of Missouri, Columbia, MO, USA
| | - Adriano E Pereira
- Division of Plant Sciences, University of Missouri, Columbia, MO, USA
| | - Deborah L Finke
- Division of Plant Sciences, University of Missouri, Columbia, MO, USA
| | - Aaron C Ericsson
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO, USA
| | - Bruce E Hibbard
- Division of Plant Sciences, University of Missouri, Columbia, MO, USA.,USDA-ARS, University of Missouri, Columbia, MO, USA
| | - Kent S Shelby
- Division of Plant Sciences, University of Missouri, Columbia, MO, USA.,USDA-ARS, Columbia, MO, USA
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11
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Bradde S, Mora T, Walczak AM. Cost and benefits of clustered regularly interspaced short palindromic repeats spacer acquisition. Philos Trans R Soc Lond B Biol Sci 2020; 374:20180095. [PMID: 30905281 PMCID: PMC6452266 DOI: 10.1098/rstb.2018.0095] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPR)-Cas-mediated immunity in bacteria allows bacterial populations to protect themselves against pathogens. However, it also exposes them to the dangers of auto-immunity by developing protection that targets its own genome. Using a simple model of the coupled dynamics of phage and bacterial populations, we explore how acquisition rates affect the probability of the bacterial colony going extinct. We find that the optimal strategy depends on the initial population sizes of both viruses and bacteria. Additionally, certain combinations of acquisition and dynamical rates and initial population sizes guarantee protection, owing to a dynamical balance between the evolving population sizes, without relying on acquisition of viral spacers. Outside this regime, the high cost of auto-immunity limits the acquisition rate. We discuss these optimal strategies that minimize the probability of the colony going extinct in terms of recent experiments. This article is part of a discussion meeting issue ‘The ecology and evolution of prokaryotic CRISPR-Cas adaptive immune systems’.
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Affiliation(s)
- Serena Bradde
- 1 American Physical Society , 1 Research Road, Ridge, NY 11961-2701 , USA.,2 David Rittenhouse Laboratories, University of Pennsylvania , Philadelphia, PA 19104 , USA
| | - Thierry Mora
- 3 Laboratoire de physique statistique, CNRS, Sorbonne Université , Paris , France.,4 Université Paris-Diderot , 24, rue Lhomond, 75005 Paris , France.,5 École Normale Supérieure (PSL University) , 24, rue Lhomond, 75005 Paris , France
| | - Aleksandra M Walczak
- 5 École Normale Supérieure (PSL University) , 24, rue Lhomond, 75005 Paris , France.,6 Laboratoire de physique théorique, CNRS, Sorbonne Université , 24, rue Lhomond, 75005 Paris , France
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12
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Jent D, Perry A, Critchlow J, Tate AT. Natural variation in the contribution of microbial density to inducible immune dynamics. Mol Ecol 2019; 28:5360-5372. [PMID: 31674070 DOI: 10.1111/mec.15293] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 10/13/2019] [Accepted: 10/21/2019] [Indexed: 12/23/2022]
Abstract
Immune responses evolve to balance the benefits of microbial killing against the costs of autoimmunity and energetic resource use. Models that explore the evolution of optimal immune responses generally include a term for constitutive immunity, or the level of immunological investment prior to microbial exposure, and for inducible immunity, or investment in immune function after microbial challenge. However, studies rarely consider the functional form of inducible immune responses with respect to microbial density, despite the theoretical dependence of immune system evolution on microbe- versus immune-mediated damage to the host. In this study, we analyse antimicrobial peptide (AMP) gene expression from seven wild-caught flour beetle populations (Tribolium spp.) during acute infection with the virulent bacteria Bacillus thuringiensis (Bt) and Photorhabdus luminescens (P.lum) to demonstrate that inducible immune responses mediated by the humoral IMD pathway exhibit natural variation in both microbe density-dependent and independent temporal dynamics. Beetle populations that exhibited greater AMP expression sensitivity to Bt density were also more likely to die from infection, while populations that exhibited higher microbe density-independent AMP expression were more likely to survive P. luminescens infection. Reduction in pathway signalling efficiency through RNAi-mediated knockdown of the imd gene reduced the magnitude of both microbe-independent and dependent responses and reduced host resistance to Bt growth, but had no net effect on host survival. This study provides a framework for understanding natural variation in the flexibility of investment in inducible immune responses and should inform theory on the contribution of nonequilibrium host-microbe dynamics to immune system evolution.
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Affiliation(s)
- Derrick Jent
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Abby Perry
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Justin Critchlow
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Ann T Tate
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
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13
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Brown LD, Shapiro LLM, Thompson GA, Estévez‐Lao TY, Hillyer JF. Transstadial immune activation in a mosquito: Adults that emerge from infected larvae have stronger antibacterial activity in their hemocoel yet increased susceptibility to malaria infection. Ecol Evol 2019; 9:6082-6095. [PMID: 31161020 PMCID: PMC6540708 DOI: 10.1002/ece3.5192] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 04/01/2019] [Accepted: 04/03/2019] [Indexed: 01/24/2023] Open
Abstract
Larval and adult mosquitoes mount immune responses against pathogens that invade their hemocoel. Although it has been suggested that a correlation exists between immune processes across insect life stages, the influence that an infection in the hemocoel of a larva has on the immune system of the eclosed adult remains unknown. Here, we used Anopheles gambiae to test whether a larval infection influences the adult response to a subsequent bacterial or malaria parasite infection. We found that for both female and male mosquitoes, a larval infection enhances the efficiency of bacterial clearance following a secondary infection in the hemocoel of adults. The adults that emerge from infected larvae have more hemocytes than adults that emerge from naive or injured larvae, and individual hemocytes have greater phagocytic activity. Furthermore, mRNA abundance of immune genes-such as cecropin A, Lysozyme C1, Stat-A, and Tep1-is higher in adults that emerge from infected larvae. A larval infection, however, does not have a meaningful effect on the probability that female adults will survive a systemic bacterial infection, and increases the susceptibility of females to Plasmodium yoelii, as measured by oocyst prevalence and intensity in the midgut. Finally, immune proficiency varies by sex; females exhibit increased bacterial killing, have twice as many hemocytes, and more highly express immune genes. Together, these results show that a larval hemocoelic infection induces transstadial immune activation-possibly via transstadial immune priming-but that it confers both costs and benefits to the emerged adults.
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Affiliation(s)
- Lisa D. Brown
- Department of Biological SciencesVanderbilt UniversityNashvilleTennessee
- Present address:
Department of BiologyGeorgia Southern UniversityStatesboroGeorgia
| | | | | | | | - Julián F. Hillyer
- Department of Biological SciencesVanderbilt UniversityNashvilleTennessee
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14
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Boots M, Best A. The evolution of constitutive and induced defences to infectious disease. Proc Biol Sci 2018; 285:rspb.2018.0658. [PMID: 30051865 PMCID: PMC6083258 DOI: 10.1098/rspb.2018.0658] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 06/21/2018] [Indexed: 01/15/2023] Open
Abstract
In response to infectious disease, hosts typically mount both constitutive and induced defences. Constitutive defence prevents infection in the first place, while induced defence typically shortens the infectious period. The two routes to defence, therefore, have very different implications not only to individuals but also to the epidemiology of the disease. Moreover, the costs of constitutive defences are likely to be paid even in the absence of disease, while induced defences are likely to incur the most substantial costs when they are used in response to infection. We examine theoretically the evolutionary implications of these fundamental differences. A key result is that high virulence in the parasite typically selects for higher induced defences even if they result in immunopathology leading to very high disease mortality. Disease impacts on fecundity are critical to the relative investment in constitutive and induced defence with important differences found when parasites castrate their hosts. The trade-off between constitutive and induced defence has been cited as a cause of the diversity in defence, but we show that the trade-off alone is unlikely to lead to diversity. Our models provide a framework to examine relative investment in different defence components both experimentally and in the field.
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Affiliation(s)
- Mike Boots
- Department of Integrative Biology, University of California, Berkeley, Berkeley CA, USA .,Department of Biosciences, University of Exeter, Penryn Campus, Penryn TR11 9FE, UK
| | - Alex Best
- School of Mathematics and Statistics, University of Sheffield, Sheffield S3 7RH, UK
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15
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Souto-Maior C, Sylvestre G, Braga Stehling Dias F, Gomes MGM, Maciel-de-Freitas R. Model-based inference from multiple dose, time course data reveals Wolbachia effects on infection profiles of type 1 dengue virus in Aedes aegypti. PLoS Negl Trop Dis 2018; 12:e0006339. [PMID: 29558464 PMCID: PMC5877886 DOI: 10.1371/journal.pntd.0006339] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 03/30/2018] [Accepted: 02/23/2018] [Indexed: 11/29/2022] Open
Abstract
Infection is a complex and dynamic process involving a population of invading microbes, the host and its responses, aimed at controlling the situation. Depending on the purpose and level of organization, infection at the organism level can be described by a process as simple as a coin toss, or as complex as a multi-factorial dynamic model; the former, for instance, may be adequate as a component of a population model, while the latter is necessary for a thorough description of the process beginning with a challenge with an infectious inoculum up to establishment or elimination of the pathogen. Experimental readouts in the laboratory are often static, snapshots of the process, assayed under some convenient experimental condition, and therefore cannot comprehensively describe the system. Different from the discrete treatment of infection in population models, or the descriptive summarized accounts of typical lab experiments, in this manuscript, infection is treated as a dynamic process dependent on the initial conditions of the infectious challenge, viral growth, and the host response along time. Here, experimental data is generated for multiple doses of type 1 dengue virus, and pathogen levels are recorded at different points in time for two populations of mosquitoes: either carrying endosymbiont bacteria Wolbachia or not. A dynamic microbe/host-response mathematical model is used to describe pathogen growth in the face of a host response like the immune system, and to infer model parameters for the two populations of insects, revealing a slight—but potentially important—protection conferred by the symbiont. Infection is usually assayed as a static observation of a pathogen within a host; it is, nevertheless, a dynamic process that cannot be described from a single time point and arbitrary conditions. Results based on the usual methods are a snapshot of a convenient laboratory condition; a more comprehensive data set is required to describe the entire process of infection from inoculation of the host with a microorganism to establishment of a systemic infection, or elimination of the threat by the host. We design an experiment that takes into account increasing pathogen challenges to a mosquito host and viral levels along time; we use a dynamic mathematical model to analyze the resulting data set. The entire framework is used to compare susceptibility to dengue virus of Aedes aegypti mosquitoes either carrying the Wolbachia symbiont or not. Instead of a simple pairwise comparison, we are able to compare infection profiles and parameters associated to host immune processes in this insect-symbiont-virus system.
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Affiliation(s)
| | - Gabriel Sylvestre
- Laboratório de Mosquitos Transmissores de Hematozoários, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil
| | | | - M. Gabriela M. Gomes
- CIBIO-InBIo, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Porto, Portugal
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Rafael Maciel-de-Freitas
- Laboratório de Mosquitos Transmissores de Hematozoários, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil
- Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM)/CNPq, Rio de Janeiro, Brazil
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16
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Schrom EC, Prada JM, Graham AL. Immune Signaling Networks: Sources of Robustness and Constrained Evolvability during Coevolution. Mol Biol Evol 2017; 35:676-687. [PMID: 29294066 DOI: 10.1093/molbev/msx321] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Defense against infection incurs costs as well as benefits that are expected to shape the evolution of optimal defense strategies. In particular, many theoretical studies have investigated contexts favoring constitutive versus inducible defenses. However, even when one immune strategy is theoretically optimal, it may be evolutionarily unachievable. This is because evolution proceeds via mutational changes to the protein interaction networks underlying immune responses, not by changes to an immune strategy directly. Here, we use a theoretical simulation model to examine how underlying network architectures constrain the evolution of immune strategies, and how these network architectures account for desirable immune properties such as inducibility and robustness. We focus on immune signaling because signaling molecules are common targets of parasitic interference but are rarely studied in this context. We find that in the presence of a coevolving parasite that disrupts immune signaling, hosts evolve constitutive defenses even when inducible defenses are theoretically optimal. This occurs for two reasons. First, there are relatively few network architectures that produce immunity that is both inducible and also robust against targeted disruption. Second, evolution toward these few robust inducible network architectures often requires intermediate steps that are vulnerable to targeted disruption. The few networks that are both robust and inducible consist of many parallel pathways of immune signaling with few connections among them. In the context of relevant empirical literature, we discuss whether this is indeed the most evolutionarily accessible robust inducible network architecture in nature, and when it can evolve.
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Affiliation(s)
- Edward C Schrom
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ
| | - Joaquín M Prada
- Mathematics Institute, University of Warwick, Coventry, United Kingdom.,Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Andrea L Graham
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ
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17
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Chabas H, van Houte S, Høyland-Kroghsbo NM, Buckling A, Westra ER. Immigration of susceptible hosts triggers the evolution of alternative parasite defence strategies. Proc Biol Sci 2017; 283:rspb.2016.0721. [PMID: 27581884 DOI: 10.1098/rspb.2016.0721] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 08/12/2016] [Indexed: 12/21/2022] Open
Abstract
Migration of hosts and parasites can have a profound impact on host-parasite ecological and evolutionary interactions. Using the bacterium Pseudomonas aeruginosa UCBPP-PA14 and its phage DMS3vir, we here show that immigration of naive hosts into coevolving populations of hosts and parasites can influence the mechanistic basis underlying host defence evolution. Specifically, we found that at high levels of bacterial immigration, bacteria switched from clustered regularly interspaced short palindromic repeats (CRISPR-Cas) to surface modification-mediated defence. This effect emerges from an increase in the force of infection, which tips the balance from CRISPR to surface modification-based defence owing to the induced and fixed fitness costs associated with these mechanisms, respectively.
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Affiliation(s)
- Hélène Chabas
- ESI, Biosciences, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK
| | - Stineke van Houte
- ESI, Biosciences, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK
| | | | - Angus Buckling
- ESI, Biosciences, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK
| | - Edze R Westra
- ESI, Biosciences, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK
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18
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Long-term genomic coevolution of host-parasite interaction in the natural environment. Nat Commun 2017; 8:111. [PMID: 28740072 PMCID: PMC5524643 DOI: 10.1038/s41467-017-00158-7] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 06/02/2017] [Indexed: 12/14/2022] Open
Abstract
Antagonistic coevolution of parasite infectivity and host resistance may alter the biological functionality of species, yet these dynamics in nature are still poorly understood. Here we show the molecular details of a long-term phage-bacterium arms race in the environment. Bacteria (Flavobacterium columnare) are generally resistant to phages from the past and susceptible to phages isolated in years after bacterial isolation. Bacterial resistance selects for increased phage infectivity and host range, which is also associated with expansion of phage genome size. We identified two CRISPR loci in the bacterial host: a type II-C locus and a type VI-B locus. While maintaining a core set of conserved spacers, phage-matching spacers appear in the variable ends of both loci over time. The spacers mostly target the terminal end of the phage genomes, which also exhibit the most variation across time, resulting in arms-race-like changes in the protospacers of the coevolving phage population.Arms races between phage and bacteria are well known from lab experiments, but insight from field systems is limited. Here, the authors show changes in the resistance and CRISPR loci of bacteria and the infectivity, host range and genome size of phage over multiple years in an aquaculture environment.
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19
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Snyder-Mackler N, Sanz J, Kohn JN, Brinkworth JF, Morrow S, Shaver AO, Grenier JC, Pique-Regi R, Johnson ZP, Wilson ME, Barreiro LB, Tung J. Social status alters immune regulation and response to infection in macaques. Science 2017; 354:1041-1045. [PMID: 27885030 DOI: 10.1126/science.aah3580] [Citation(s) in RCA: 183] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 10/17/2016] [Indexed: 12/13/2022]
Abstract
Social status is one of the strongest predictors of human disease risk and mortality, and it also influences Darwinian fitness in social mammals more generally. To understand the biological basis of these effects, we combined genomics with a social status manipulation in female rhesus macaques to investigate how status alters immune function. We demonstrate causal but largely plastic social status effects on immune cell proportions, cell type-specific gene expression levels, and the gene expression response to immune challenge. Further, we identify specific transcription factor signaling pathways that explain these differences, including low-status-associated polarization of the Toll-like receptor 4 signaling pathway toward a proinflammatory response. Our findings provide insight into the direct biological effects of social inequality on immune function, thus improving our understanding of social gradients in health.
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Affiliation(s)
- Noah Snyder-Mackler
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708, USA.,Duke Center for the Study of Aging and Human Development, Duke University, Durham, NC 27708, USA
| | - Joaquín Sanz
- Department of Biochemistry, Faculty of Medicine, Université de Montréal, Montréal, Quebec H3T1J4, Canada.,Department of Genetics, Centre Hospitalier Universitaire Sainte-Justine Research Center, Montréal, Quebec H3T1C5, Canada
| | - Jordan N Kohn
- Yerkes National Primate Research Center, Emory University, Atlanta, GA 30322, USA
| | - Jessica F Brinkworth
- Department of Biochemistry, Faculty of Medicine, Université de Montréal, Montréal, Quebec H3T1J4, Canada.,Department of Anthropology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Shauna Morrow
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708, USA
| | - Amanda O Shaver
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708, USA
| | - Jean-Christophe Grenier
- Department of Genetics, Centre Hospitalier Universitaire Sainte-Justine Research Center, Montréal, Quebec H3T1C5, Canada
| | - Roger Pique-Regi
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, MI 48201, USA.,Department of Obstetrics and Gynecology, Wayne State University, Detroit, MI 48201, USA
| | - Zachary P Johnson
- Yerkes National Primate Research Center, Emory University, Atlanta, GA 30322, USA.,Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Mark E Wilson
- Yerkes National Primate Research Center, Emory University, Atlanta, GA 30322, USA.,Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Luis B Barreiro
- Department of Genetics, Centre Hospitalier Universitaire Sainte-Justine Research Center, Montréal, Quebec H3T1C5, Canada. .,Department of Pediatrics, Faculty of Medicine, Université de Montréal, Montréal, Quebec H3T1J4, Canada
| | - Jenny Tung
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708, USA. .,Department of Biology, Duke University, Durham, NC 27708, USA.,Institute of Primate Research, National Museums of Kenya, Nairobi 00502, Kenya.,Duke Population Research Institute, Duke University, Durham, NC 27708, USA
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20
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Üveges B, Fera G, Móricz ÁM, Krüzselyi D, Bókony V, Hettyey A. Age- and environment-dependent changes in chemical defences of larval and post-metamorphic toads. BMC Evol Biol 2017; 17:137. [PMID: 28610604 PMCID: PMC5470210 DOI: 10.1186/s12862-017-0956-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Accepted: 04/25/2017] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Chemical defences are widespread in animals, but how their production is adjusted to ecological conditions is poorly known. Optimal defence theory predicts that inducible defences are favoured over constitutive defences when toxin production is costly and the need for it varies across environments. However, if some environmental changes occur predictably (e.g. coupled to transitions during ontogeny), whereas others are unpredictable (e.g. predation, food availability), changes in defences may have constitutive as well as plastic elements. To investigate this phenomenon, we raised common toad (Bufo bufo) tadpoles with ad libitum or limited food and in the presence or absence of chemical cues on predation risk, and measured their toxin content on 5 occasions during early ontogeny. RESULTS The number of compounds showed limited variation with age in tadpoles and was unaffected by food limitation and predator cues. The total amount of bufadienolides first increased and later decreased during development, and it was elevated in young and mid-aged tadpoles with limited food availability compared to their ad libitum fed conspecifics, whereas it did not change in response to cues on predation risk. We provide the first evidence for the active synthesis of defensive toxin compounds this early during ontogeny in amphibians. Furthermore, the observation of increased quantities of bufadienolides in food-restricted tadpoles is the first experimental demonstration of resource-dependent induction of elevated de novo toxin production, suggesting a role for bufadienolides in allelopathy. CONCLUSIONS Our study shows that the evolution of phenotypic plasticity in chemical defences may depend on the ecological context (i.e. predation vs. competition). Our results furthermore suggest that the age-dependent changes in the diversity of toxin compounds in developing toads may be fixed (i.e., constitutive), timed for the developmental stages in which they are most reliant on their chemical arsenal, whereas inducible plasticity may prevail in the amount of synthesized compounds.
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Affiliation(s)
- Bálint Üveges
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó út 15, Budapest, 1022 Hungary
| | - Gábor Fera
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó út 15, Budapest, 1022 Hungary
| | - Ágnes M. Móricz
- Department of Pathophysiology, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó út 15, Budapest, 1022 Hungary
| | - Dániel Krüzselyi
- Department of Pathophysiology, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó út 15, Budapest, 1022 Hungary
| | - Veronika Bókony
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó út 15, Budapest, 1022 Hungary
| | - Attila Hettyey
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó út 15, Budapest, 1022 Hungary
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21
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Simone-Finstrom M. Social Immunity and the Superorganism: Behavioral Defenses Protecting Honey Bee Colonies from Pathogens and Parasites. ACTA ACUST UNITED AC 2017. [DOI: 10.1080/0005772x.2017.1307800] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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22
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Westra ER, Dowling AJ, Broniewski JM, van Houte S. Evolution and Ecology of CRISPR. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2016. [DOI: 10.1146/annurev-ecolsys-121415-032428] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Edze R. Westra
- Environment and Sustainability Institute and Centre for Ecology and Conservation, Biosciences, University of Exeter, Tremough Campus, Penryn TR10 9FE, United Kingdom;
| | - Andrea J. Dowling
- Environment and Sustainability Institute and Centre for Ecology and Conservation, Biosciences, University of Exeter, Tremough Campus, Penryn TR10 9FE, United Kingdom;
| | - Jenny M. Broniewski
- Environment and Sustainability Institute and Centre for Ecology and Conservation, Biosciences, University of Exeter, Tremough Campus, Penryn TR10 9FE, United Kingdom;
| | - Stineke van Houte
- Environment and Sustainability Institute and Centre for Ecology and Conservation, Biosciences, University of Exeter, Tremough Campus, Penryn TR10 9FE, United Kingdom;
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23
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Beemelmanns A, Roth O. Bacteria-type-specific biparental immune priming in the pipefish Syngnathus typhle. Ecol Evol 2016; 6:6735-6757. [PMID: 27777744 PMCID: PMC5058542 DOI: 10.1002/ece3.2391] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 07/27/2016] [Accepted: 08/01/2016] [Indexed: 12/29/2022] Open
Abstract
The transfer of acquired and specific immunity against previously encountered bacteria from mothers to offspring boosts the immune response of the next generation and supports the development of a successful pathogen defense. While most studies claim that the transfer of immunity is a maternal trait, in the sex-role-reversed pipefish Syngnathus typhle, fathers nurse the embryos over a placenta-like structure, which opens the door for additional paternal immune priming. We examined the potential and persistence of bacteria-type-specific parental immune priming in the pipefish S. typhle over maturation time using a fully reciprocal design with two different bacteria species (Vibrio spp. and Tenacibaculum maritimum). Our results suggest that S. typhle is able to specifically prime the next generation against prevalent local bacteria and to a limited extent even also against newly introduced bacteria species. Long-term protection was thereby maintained only against prevailing Vibrio bacteria. Maternal and paternal transgenerational immune priming can complement each other, as they affect different pathways of the offspring immune system and come with distinct degree of specificity. The differential regulation of DNA-methylation genes upon parental bacteria exposure in premature pipefish offspring indicates that epigenetic regulation processes are involved in transferring immune-related information across generations. The identified trade-offs between immune priming and reproduction determine TGIP as a costly trait, which might constrain the evolution of long-lasting TGIP, if parental and offspring generations do not share the same parasite assembly.
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Affiliation(s)
- Anne Beemelmanns
- Helmholtz‐Centre for Ocean Research Kiel (GEOMAR)Evolutionary Ecology of Marine FishesDüsternbrooker Weg 2024105KielGermany
| | - Olivia Roth
- Helmholtz‐Centre for Ocean Research Kiel (GEOMAR)Evolutionary Ecology of Marine FishesDüsternbrooker Weg 2024105KielGermany
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24
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Kamiya T, Oña L, Wertheim B, van Doorn GS. Coevolutionary feedback elevates constitutive immune defence: a protein network model. BMC Evol Biol 2016; 16:92. [PMID: 27150135 PMCID: PMC4858902 DOI: 10.1186/s12862-016-0667-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 04/23/2016] [Indexed: 11/19/2022] Open
Abstract
Background Organisms have evolved a variety of defence mechanisms against natural enemies, which are typically used at the expense of other life history components. Induced defence mechanisms impose minor costs when pathogens are absent, but mounting an induced response can be time-consuming. Therefore, to ensure timely protection, organisms may partly rely on constitutive defence despite its sustained cost that renders it less economical. Existing theoretical models addressing the optimal combination of constitutive versus induced defence focus solely on host adaptation and ignore the fact that the efficacy of protection depends on genotype-specific host-parasite interactions. Here, we develop a signal-transduction network model inspired by the invertebrate innate immune system, in order to address the effect of parasite coevolution on the optimal combination of constitutive and induced defence. Results Our analysis reveals that coevolution of parasites with specific immune components shifts the host’s optimal allocation from induced towards constitutive immunity. This effect is dependent upon whether receptors (for detection) or effectors (for elimination) are subjected to parasite counter-evolution. A parasite population subjected to a specific immune receptor can evolve heightened genetic diversity, which makes parasite detection more difficult for the hosts. We show that this coevolutionary feedback renders the induced immune response less efficient, forcing the hosts to invest more heavily in constitutive immunity. Parasites diversify to escape elimination by a specific effector too. However, this diversification does not alter the optimal balance between constitutive and induced defence: the reliance on constitutive defence is promoted by the receptor’s inability to detect, but not the effectors’ inability to eliminate parasites. If effectors are useless, hosts simply adapt to tolerate, rather than to invest in any defence against parasites. These contrasting results indicate that evolutionary feedback between host and parasite populations is a key factor shaping the selection regime for immune networks facing antagonistic coevolution. Conclusion Parasite coevolution against specific immune defence alters the prediction of the optimal use of defence, and the effect of parasite coevolution varies between different immune components. Electronic supplementary material The online version of this article (doi:10.1186/s12862-016-0667-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tsukushi Kamiya
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, P.O. Box 11103, CC Groningen, 9700, The Netherlands. .,Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Canada.
| | - Leonardo Oña
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, P.O. Box 11103, CC Groningen, 9700, The Netherlands
| | - Bregje Wertheim
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, P.O. Box 11103, CC Groningen, 9700, The Netherlands
| | - G Sander van Doorn
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, P.O. Box 11103, CC Groningen, 9700, The Netherlands
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25
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Cressler CE, Graham AL, Day T. Evolution of hosts paying manifold costs of defence. Proc Biol Sci 2015; 282:20150065. [PMID: 25740895 DOI: 10.1098/rspb.2015.0065] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Hosts are expected to incur several physiological costs in defending against parasites. These include constitutive energetic (or other resource) costs of a defence system, facultative resource costs of deploying defences when parasites strike, and immunopathological costs of collateral damage. Here, we investigate the evolution of host recovery rates, varying the source and magnitude of immune costs. In line with previous work, we find that hosts paying facultative resource costs evolve faster recovery rates than hosts paying constitutive costs. However, recovery rate is more sensitive to changes in facultative costs, potentially explaining why constitutive costs are hard to detect empirically. Moreover, we find that immunopathology costs which increase with recovery rate can erode the benefits of defence, promoting chronicity of infection. Immunopathology can also lead to hosts evolving low recovery rate in response to virulent parasites. Furthermore, when immunopathology reduces fecundity as recovery rate increases (e.g. as for T-cell responses to urogenital chlamydiosis), then recovery and reproductive rates do not covary as predicted in eco-immunology. These results suggest that immunopathological and resource costs have qualitatively different effects on host evolution and that embracing the complexity of immune costs may be essential for explaining variability in immune defence in nature.
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Affiliation(s)
- Clayton E Cressler
- Department of Mathematics and Statistics, Queen's University, Kingston, Ontario, Canada K7L 3N6
| | - Andrea L Graham
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA
| | - Troy Day
- Department of Mathematics and Statistics, Queen's University, Kingston, Ontario, Canada K7L 3N6 Department of Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6
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26
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Tate AT, Graham AL. Dynamic Patterns of Parasitism and Immunity across Host Development Influence Optimal Strategies of Resource Allocation. Am Nat 2015; 186:495-512. [DOI: 10.1086/682705] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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28
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Parasite Exposure Drives Selective Evolution of Constitutive versus Inducible Defense. Curr Biol 2015; 25:1043-9. [PMID: 25772450 DOI: 10.1016/j.cub.2015.01.065] [Citation(s) in RCA: 179] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 01/09/2015] [Accepted: 01/28/2015] [Indexed: 12/26/2022]
Abstract
In the face of infectious disease, organisms evolved a range of defense mechanisms, with a clear distinction between those that are constitutive (always active) and those that are inducible (elicited by parasites). Both defense strategies have evolved from each other, but we lack an understanding of the conditions that favor one strategy over the other. While it is hard to generalize about their degree of protection, it is possible to make generalizations about their associated fitness costs, which are commonly detected. By definition, constitutive defenses are always "on," and are therefore associated with a fixed cost, independent of parasite exposure. Inducible defenses, on the other hand, may lack costs in the absence of parasites but become costly when defense is elicited through processes such as immunopathology. Bacteria can evolve constitutive defense against phage by modification/masking of surface receptors, which is often associated with reduced fitness in the absence of phage. Bacteria can also evolve inducible defense using the CRISPR-Cas (clustered regularly interspaced short palindromic repeat, CRISPR associated) immune system, which is typically elicited upon infection. CRISPR-Cas functions by integrating phage sequences into CRISPR loci on the host genome. Upon re-infection, CRISPR transcripts guide cleavage of phage genomes. In nature, both mechanisms are important. Using a general theoretical model and experimental evolution, we tease apart the mechanism that drives their evolution and show that infection risk determines the relative investment in the two arms of defense.
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29
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Kennedy DA, Dukic V, Dwyer G. Pathogen growth in insect hosts: inferring the importance of different mechanisms using stochastic models and response-time data. Am Nat 2014; 184:407-23. [PMID: 25141148 PMCID: PMC10495239 DOI: 10.1086/677308] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Pathogen population dynamics within individual hosts can alter disease epidemics and pathogen evolution, but our understanding of the mechanisms driving within-host dynamics is weak. Mathematical models have provided useful insights, but existing models have only rarely been subjected to rigorous tests, and their reliability is therefore open to question. Most models assume that initial pathogen population sizes are so large that stochastic effects due to small population sizes, so-called demographic stochasticity, are negligible, but whether this assumption is reasonable is unknown. Most models also assume that the dynamic effects of a host's immune system strongly affect pathogen incubation times or "response times," but whether such effects are important in real host-pathogen interactions is likewise unknown. Here we use data for a baculovirus of the gypsy moth to test models of within-host pathogen growth. By using Bayesian statistical techniques and formal model-selection procedures, we are able to show that the response time of the gypsy moth virus is strongly affected by both demographic stochasticity and a dynamic response of the host immune system. Our results imply that not all response-time variability can be explained by host and pathogen variability, and that immune system responses to infection may have important effects on population-level disease dynamics.
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Affiliation(s)
- David A. Kennedy
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, Pennsylvania 16802
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland 20892
| | - Vanja Dukic
- Department of Applied Mathematics, University of Colorado, Boulder, Colorado 80305
| | - Greg Dwyer
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637
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Hoverman JT, Hoye BJ, Johnson PTJ. Does timing matter? How priority effects influence the outcome of parasite interactions within hosts. Oecologia 2013; 173:1471-80. [DOI: 10.1007/s00442-013-2692-x] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Accepted: 05/16/2013] [Indexed: 11/29/2022]
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Russo J, Madec L. Linking immune patterns and life history shows two distinct defense strategies in land snails (gastropoda, pulmonata). Physiol Biochem Zool 2013; 86:193-204. [PMID: 23434779 DOI: 10.1086/669482] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Life history integration of the defense response was investigated at intra- and interspecific levels in land snails of the family Helicidae. Two hypotheses were tested: (i) fitness consequences of defense responses are closely related to life history traits such as size at maturity and life span; (ii) different pathways of the immune response based on "nonspecific" versus "specific" responses may reflect different defense options. Relevant immune responses to a challenge with E. coli were measured using the following variables: blood cell density, cellular or plasma antibacterial activity via reactive oxygen species (ROS) level, and bacterial growth inhibition. The results revealed that the largest snails did not exhibit the strongest immune response. Instead, body mass influenced the type of response in determining the appropriate strategy. Snails with a higher body mass at maturity had more robust plasma immune responses than snails with a lower mass, which had greater cell-mediated immune responses with a higher hemocyte density. In addition, ROS appeared also to be a stress mediator as attested by differences between sites and generations for the same species.
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Affiliation(s)
- Jacqueline Russo
- Université de Rennes 1, Unité Mixte de Recherche 6553 ECOBIO, Campus de Beaulieu, Rennes Cedex, France.
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Ponton F, Wilson K, Holmes AJ, Cotter SC, Raubenheimer D, Simpson SJ. Integrating nutrition and immunology: a new frontier. JOURNAL OF INSECT PHYSIOLOGY 2013; 59:130-7. [PMID: 23159523 DOI: 10.1016/j.jinsphys.2012.10.011] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 10/09/2012] [Accepted: 10/09/2012] [Indexed: 05/20/2023]
Abstract
Nutrition is critical to immune defence and parasite resistance, which not only affects individual organisms, but also has profound ecological and evolutionary consequences. Nutrition and immunity are complex traits that interact via multiple direct and indirect pathways, including the direct effects of nutrition on host immunity but also indirect effects mediated by the host's microbiota and pathogen populations. The challenge remains, however, to capture the complexity of the network of interactions that defines nutritional immunology. The aim of this paper is to discuss the recent findings in nutritional research in the context of immunological studies. By taking examples from the entomological literature, we argue that insects provide a powerful tool for examining the network of interactions between nutrition and immunity due to their tractability, short lifespan and ethical considerations. We describe the relationships between dietary composition, immunity, disease and microbiota in insects, and highlight the importance of adopting an integrative and multi-dimensional approach to nutritional immunology.
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Affiliation(s)
- Fleur Ponton
- School of Biological Sciences, The University of Sydney, Sydney, New South Wales 2006, Australia.
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Vézilier J, Nicot A, Lorgeril J, Gandon S, Rivero A. The impact of insecticide resistance on Culex pipiens immunity. Evol Appl 2012; 6:497-509. [PMID: 23745141 PMCID: PMC3673477 DOI: 10.1111/eva.12037] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2012] [Revised: 10/30/2012] [Accepted: 11/05/2012] [Indexed: 11/28/2022] Open
Abstract
Because of their role as vectors of diseases, the evolution of insecticide resistance in mosquitoes has been intensively investigated. Insecticide resistance is associated to a wide range of pleiotropic effects on several key life-history traits of mosquitoes such as longevity and behavior. However, despite its potential implications in pathogen transmission, the effects of insecticide resistance on mosquito immunity have received little, if any, attention. Here, we investigate the impact of insecticide resistance in Culex pipiens, an epidemiologically important vector of a wide array of pathogens. Using both isogenic laboratory strains and field-caught mosquitoes, we investigate the impact of two main insecticide resistance mechanisms (metabolic detoxification and target site modification) on the relative transcription of several genes involved in the immune response to pathogens, at both their constitutive and inducible levels. Our results show a discrepancy between the isogenic laboratory lines and field-collected mosquitoes: While in the isogenic strains, insecticide-resistant mosquitoes show a drastic increase in immune gene expression, no such effect appears in the field. We speculate on the different mechanisms that may underlie this discrepancy and discuss the risks of making inferences on the pleiotropic effects of insecticide-resistant genes by using laboratory-selected insecticide-resistant lines.
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Affiliation(s)
- Julien Vézilier
- MIVEGEC (CNRS UMR 5290), Centre de Recherche IRD Montpellier, France
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34
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White S, Burden J, Maini P, Hails R. Modelling the within-host growth of viral infections in insects. J Theor Biol 2012; 312:34-43. [PMID: 22877574 DOI: 10.1016/j.jtbi.2012.07.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 05/16/2012] [Accepted: 07/23/2012] [Indexed: 10/28/2022]
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Ali A, Moushib LI, Lenman M, Levander F, Olsson K, Carlson-Nilson U, Zoteyeva N, Liljeroth E, Andreasson E. Paranoid potato: phytophthora-resistant genotype shows constitutively activated defense. PLANT SIGNALING & BEHAVIOR 2012; 7:400-8. [PMID: 22476463 PMCID: PMC3443922 DOI: 10.4161/psb.19149] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Phytophthora is the most devastating pathogen of dicot plants. There is a need for resistance sources with different modes of action to counteract the fast evolution of this pathogen. In order to better understand mechanisms of defense against P. infestans, we analyzed several clones of potato. Two of the genotypes tested, Sarpo Mira and SW93-1015, exhibited strong resistance against P. infestans in field trials, whole plant assays and detached leaf assays. The resistant genotypes developed different sizes of hypersensitive response (HR)-related lesions. HR lesions in SW93-1015 were restricted to very small areas, whereas those in Sarpo Mira were similar to those in Solanum demissum, the main source of classical resistance genes. SW93-1015 can be characterized as a cpr (constitutive expressor of PR genes) genotype without spontaneous microscopic or macroscopic HR lesions. This is indicated by constitutive hydrogen peroxide (H₂O₂) production and PR1 (pathogenesis-related protein 1) secretion. SW93-1015 is one of the first plants identified as having classical protein-based induced defense expressed constitutively without any obvious metabolic costs or spontaneous cell death lesions.
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Affiliation(s)
- Ashfaq Ali
- Department of Biology; Lund University; Lund, Sweden
| | | | - Marit Lenman
- Department of Plant Protection Biology; Swedish University of Agricultural Sciences; Alnarp, Sweden
| | | | - Kerstin Olsson
- Department of Plant Breeding and Biotechnology; Swedish University of Agricultural Sciences; Alnarp, Sweden
| | - Ulrika Carlson-Nilson
- Department of Plant Breeding and Biotechnology; Swedish University of Agricultural Sciences; Alnarp, Sweden
| | - Nadezhda Zoteyeva
- Genetic Department of N.I. Vavilov Institute of Plant Industry; St. Petersburg, Russia
| | - Erland Liljeroth
- Department of Plant Protection Biology; Swedish University of Agricultural Sciences; Alnarp, Sweden
| | - Erik Andreasson
- Department of Plant Protection Biology; Swedish University of Agricultural Sciences; Alnarp, Sweden
- Correspondence to: Erik Andreasson,
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Schulte RD, Hasert B, Makus C, Michiels NK, Schulenburg H. Increased responsiveness in feeding behaviour of Caenorhabditis elegans after experimental coevolution with its microparasite Bacillus thuringiensis. Biol Lett 2011; 8:234-6. [PMID: 21880622 DOI: 10.1098/rsbl.2011.0684] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Immune responses, either constitutive or induced, are costly. An alternative defence strategy may be based on behavioural responses. For example, avoidance behaviour reduces contact with pathogens and thus the risk of infection as well as the requirement of immune system activation. Similarly, if pathogens are taken up orally, preferential feeding of pathogen-free food may be advantageous. Behavioural defences have been found in many animals, including the nematode Caenorhabditis elegans. We here tested nematodes from a laboratory based evolution experiment which had either coevolved with their microparasite Bacillus thuringiensis (BT) or evolved under control conditions. After 48 generations, coevolved populations were more sensitive to food conditions: in comparison with the controls, they reduced feeding activity in the presence of pathogenic BT strains while at the same time increasing it in the presence of non-pathogenic strains. We conclude that host-parasite coevolution can drive changes in the behavioural responsiveness to bacterial microbes, potentially leading to an increased defence against pathogens.
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Affiliation(s)
- Rebecca D Schulte
- Institute for Evolution and Biodiversity, University of Muenster, Muenster, Germany.
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Armitage SAO, Broch JF, Marín HF, Nash DR, Boomsma JJ. Immune defense in leaf-cutting ants: a cross-fostering approach. Evolution 2011; 65:1791-9. [PMID: 21644963 DOI: 10.1111/j.1558-5646.2011.01241.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To ameliorate the impact of disease, social insects combine individual innate immune defenses with collective social defenses. This implies that there are different levels of selection acting on investment in immunity, each with their own trade-offs. We present the results of a cross-fostering experiment designed to address the influences of genotype and social rearing environment upon individual and social immune defenses. We used a multiply mating leaf-cutting ant, enabling us to test for patriline effects within a colony, as well as cross-colony matriline effects. The worker's father influenced both individual innate immunity (constitutive antibacterial activity) and the size of the metapleural gland, which secretes antimicrobial compounds and functions in individual and social defense, indicating multiple mating could have important consequences for both defense types. However, the primarily social defense, a Pseudonocardia bacteria that helps to control pathogens in the ants' fungus garden, showed a significant colony of origin by rearing environment interaction, whereby ants that acquired the bacteria of a foster colony obtained a less abundant cover of bacteria: one explanation for this pattern would be co-adaptation between host colonies and their vertically transmitted mutualist. These results illustrate the complexity of the selection pressures that affect the expression of multilevel immune defenses.
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Affiliation(s)
- Sophie A O Armitage
- Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark.
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Elliot SL, Hart AG. Density-dependent prophylactic immunity reconsidered in the light of host group living and social behavior. Ecology 2010; 91:65-72. [PMID: 20380197 DOI: 10.1890/09-0424.1] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
According to the density-dependent hypothesis (DDP), hosts living at high densities suffer greater risk of disease and so invest more in immunity. Although there is much empirical support for this, especially from invertebrate systems, there are many exceptions, notably in social insects. We propose that (A) density is not always the most appropriate population parameter to use when considering the risks associated with disease and (B) behavioral defenses should be given a greater emphasis in considerations of a host's repertoire of immune defenses. We propose a complementary framework stressing the connectivity between and within populations as a starting point and emphasizing the costs represented by disease above the risk of disease per se. We consider the components of immune defense and propose that behaviors may represent lower-cost defenses than their physiological counterparts. As group-living and particularly social animals will have a greater behavioral repertoire, we conclude that with group living comes a greater capacity for behavioral immune defense, most particularly for social insects. This may escape our notice if we consider physiological parameters alone.
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Affiliation(s)
- Simon L Elliot
- Department of Animal Biology, Federal University of Viçosa, Vi,cosa, MG, 36571-000, Brazil.
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Optimal defense strategy against herbivory in plants: conditions selecting for induced defense, constitutive defense, and no-defense. J Theor Biol 2009; 260:453-9. [PMID: 19591847 DOI: 10.1016/j.jtbi.2009.07.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 06/30/2009] [Accepted: 07/02/2009] [Indexed: 11/21/2022]
Abstract
To examine the conditions selecting for induced defense, constitutive defense, and no-defense, we developed a model of plant defense strategy against herbivory. In the model, a plant consists of two modules between which signal inducing defense compounds can be translocated. We assume three strategies: plants produce defense compounds responding to herbivory (induced defense), they have the compounds beforehand (constitutive defense), and they never produce the compounds (no-defense). We found that no-defense is optimal if the amount of biomass lost due to herbivory is small because of the growth cost of having defense compounds. The constitutive defense is optimal if the amount of biomass lost is not so small and the probability of herbivory is high. If the biomass loss is not so small but the probability of herbivory is low, the induced defense or no-defense is optimal. When the induced defense is optimal, the probability of herbivory necessarily increases in plants once herbivory has occurred. If the probability stays the same, no-defense is optimal. Thus, the behavior of herbivores, i.e., whether they remain around a plant and attack it repeatedly, affects the evolution of the induced defense.
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Sorci G, Faivre B. Inflammation and oxidative stress in vertebrate host-parasite systems. Philos Trans R Soc Lond B Biol Sci 2009; 364:71-83. [PMID: 18930878 DOI: 10.1098/rstb.2008.0151] [Citation(s) in RCA: 218] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Innate, inflammation-based immunity is the first line of vertebrate defence against micro-organisms. Inflammation relies on a number of cellular and molecular effectors that can strike invading pathogens very shortly after the encounter between inflammatory cells and the intruder, but in a non-specific way. Owing to this non-specific response, inflammation can generate substantial costs for the host if the inflammatory response, and the associated oxygen-based damage, get out of control. This imposes strong selection pressure that acts to optimize two key features of the inflammatory response: the timing of activation and resolution (the process of downregulation of the response). In this paper, we review the benefits and costs of inflammation-driven immunity. Our aim is to emphasize the importance of resolution of inflammation as a way of maintaining homeostasis against oxidative stress and to prevent the 'horror autotoxicus' of chronic inflammation. Nevertheless, host immune regulation also opens the way to pathogens to subvert host defences. Therefore, quantifying inflammatory costs requires assessing (i) short-term negative effects, (ii) delayed inflammation-driven diseases, and (iii) parasitic strategies to subvert inflammation.
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Affiliation(s)
- Gabriele Sorci
- BioGéoSciences, CNRS UMR 5561, Université de Bourgogne, 6 Boulevard Gabriel, 21000 Dijon, France.
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Abstract
Strepsiptera are obligate endoparasitoids that exhibit extreme sexual dimorphism and parasitize seven orders and 33 families of Insecta. The adult males and the first instar larvae in the Mengenillidia and Stylopidia are free-living, whereas the adult females in Mengenillidia are free-living but in the suborder Stylopidia they remain endoparasitic in the host. Parasitism occurs at the host larval/nymphal stage and continues in a mobile host until that host's adult stage. The life of the host is lengthened to allow the male strepsipteran to complete maturation and the viviparous female to release the first instar larvae when the next generation of the host's larvae/nymphs has been produced. The ability of strepsipterans to parasitize a wide range of hosts, in spite of being endoparasitoids, is perhaps due to their unique immune avoidance system. Aspects of virulence, heterotrophic heteronomy in the family Myrmecolacidae, cryptic species, genomics, immune response, and behavior of stylopized hosts are discussed in this chapter.
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