1
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Douglas AJ, Katzenback BA. The wood frog (Rana sylvatica): An emerging comparative model for anuran immunity and host-ranavirus interactions. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2023; 147:104733. [PMID: 37550009 DOI: 10.1016/j.dci.2023.104733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Revised: 05/06/2023] [Accepted: 05/09/2023] [Indexed: 08/09/2023]
Abstract
The wood frog (Rana sylvatica) is widely distributed across North America and is the only amphibian found north of the Arctic Circle due to its remarkable ability to tolerate whole-body freezing. Recent mass mortalities attributable to Ranavirus spp. (family Iridoviridae) in wild juvenile wood frogs, coupled with the apparent high susceptibility of wood frogs to experimental infection with frog virus 3 (FV3), the type species of the Ranavirus genus, or FV3-like isolates underscore the serious threat ranaviruses poses to wood frog populations. Despite the ecological relevance and unique life history of wood frogs, our understanding of the wood frog immune system and antiviral response to ranaviral infections is in its infancy. Here we aim to (1) synthesize the limited knowledge of wood frog immune defences, (2) review recent progress in establishing the wood frog as a study system for ranavirus infection, and (3) highlight the future use of wood frogs as a model anuran to provide insight into the evolution of anuran immune systems and antiviral responses.
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Affiliation(s)
- Alexander J Douglas
- Department of Biology, University of Waterloo, Waterloo, Ontario, N2L3G1, Canada
| | - Barbara A Katzenback
- Department of Biology, University of Waterloo, Waterloo, Ontario, N2L3G1, Canada.
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2
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Hughey MC, Warne R, Dulmage A, Reeve RE, Curtis GH, Whitfield K, Schock DM, Crespi E. Diet- and salinity-induced modifications of the gut microbiota are associated with differential physiological responses to ranavirus infection in Rana sylvatica. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220121. [PMID: 37305908 PMCID: PMC10258663 DOI: 10.1098/rstb.2022.0121] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Accepted: 03/26/2023] [Indexed: 06/13/2023] Open
Abstract
Greater knowledge of how host-microbiome interactions vary with anthropogenic environmental change and influence pathogenic infections is needed to better understand stress-mediated disease outcomes. We investigated how increasing salinization in freshwaters (e.g. due to road de-icing salt runoff) and associated increases in growth of nutritional algae influenced gut bacterial assembly, host physiology and responses to ranavirus exposure in larval wood frogs (Rana sylvatica). Elevating salinity and supplementing a basic larval diet with algae increased larval growth and also increased ranavirus loads. However, larvae given algae did not exhibit elevated kidney corticosterone levels, accelerated development or weight loss post-infection, whereas larvae fed a basic diet did. Thus, algal supplementation reversed a potentially maladaptive stress response to infection observed in prior studies in this system. Algae supplementation also reduced gut bacterial diversity. Notably, we observed higher relative abundances of Firmicutes in treatments with algae-a pattern consistent with increased growth and fat deposition in mammals-that may contribute to the diminished stress responses to infection via regulation of host metabolism and endocrine function. Our study informs mechanistic hypotheses about the role of microbiome mediation of host responses to infection that can be tested in future experiments in this host-pathogen system. This article is part of the theme issue 'Amphibian immunity: stress, disease and ecoimmunology'.
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Affiliation(s)
- Myra C. Hughey
- Department of Biology, Vassar College, Poughkeepsie, NY 12604, USA
| | - Robin Warne
- School of Biological Sciences, Southern Illinois University, Carbondale, IL 62901, USA
| | - Alexa Dulmage
- School of Biological Sciences, Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA
| | - Robyn E. Reeve
- School of Biological Sciences, Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA
| | - Grace H. Curtis
- School of Biological Sciences, Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA
| | - Kourtnie Whitfield
- School of Biological Sciences, Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA
| | | | - Erica Crespi
- School of Biological Sciences, Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA
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3
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Humphries JE, Lanctôt CM, Robert J, McCallum HI, Newell DA, Grogan LF. Do immune system changes at metamorphosis predict vulnerability to chytridiomycosis? An update. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2022; 136:104510. [PMID: 35985564 DOI: 10.1016/j.dci.2022.104510] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 06/20/2022] [Accepted: 07/15/2022] [Indexed: 06/15/2023]
Abstract
Amphibians are among the vertebrate groups suffering great losses of biodiversity due to a variety of causes including diseases, such as chytridiomycosis (caused by the fungal pathogens Batrachochytrium dendrobatidis and B. salamandrivorans). The amphibian metamorphic period has been identified as being particularly vulnerable to chytridiomycosis, with dramatic physiological and immunological reorganisation likely contributing to this vulnerability. Here, we overview the processes behind these changes at metamorphosis and then perform a systematic literature review to capture the breadth of empirical research performed over the last two decades on the metamorphic immune response. We found that few studies focused specifically on the immune response during the peri-metamorphic stages of amphibian development and fewer still on the implications of their findings with respect to chytridiomycosis. We recommend future studies consider components of the immune system that are currently under-represented in the literature on amphibian metamorphosis, particularly pathogen recognition pathways. Although logistically challenging, we suggest varying the timing of exposure to Bd across metamorphosis to examine the relative importance of pathogen evasion, suppression or dysregulation of the immune system. We also suggest elucidating the underlying mechanisms of the increased susceptibility to chytridiomycosis at metamorphosis and the associated implications for population persistence. For species that overlap a distribution where Bd/Bsal are now endemic, we recommend a greater focus on management strategies that consider the important peri-metamorphic period.
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Affiliation(s)
- Josephine E Humphries
- School of Environment and Science, Griffith University, Southport, Queensland, 4222, Australia; Centre for Planetary Health and Food Security, Griffith University, Southport, Queensland, 4222, Australia; Faculty of Science and Engineering, Southern Cross University, Lismore, New South Wales, 2480, Australia.
| | - Chantal M Lanctôt
- School of Environment and Science, Griffith University, Southport, Queensland, 4222, Australia; Australian Rivers Institute, Griffith University, Southport, Queensland, 4222, Australia
| | - Jacques Robert
- Department of Microbiology and Immunology, University of Rochester Medical Center, 14642, Rochester, NY, United States
| | - Hamish I McCallum
- School of Environment and Science, Griffith University, Southport, Queensland, 4222, Australia; Centre for Planetary Health and Food Security, Griffith University, Southport, Queensland, 4222, Australia
| | - David A Newell
- Faculty of Science and Engineering, Southern Cross University, Lismore, New South Wales, 2480, Australia
| | - Laura F Grogan
- School of Environment and Science, Griffith University, Southport, Queensland, 4222, Australia; Centre for Planetary Health and Food Security, Griffith University, Southport, Queensland, 4222, Australia
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4
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Hou J, Long J, Xiang J, Pan W, Li D, Liu X. Ontogenetic characteristics of the intestinal microbiota of
Quasipaa spinosa
revealed by
16S rRNA
gene sequencing. Lett Appl Microbiol 2022; 75:1182-1192. [DOI: 10.1111/lam.13786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 07/01/2022] [Accepted: 07/05/2022] [Indexed: 11/30/2022]
Affiliation(s)
- Jingliang Hou
- College of Animal Science and Technology Hunan Agricultural University Changsha Hunan China
| | - Jiahang Long
- Hunan Fisheries Science Institute Changsha Hunan China
| | - Jianguo Xiang
- College of Animal Science and Technology Hunan Agricultural University Changsha Hunan China
| | | | - Deliang Li
- College of Animal Science and Technology Hunan Agricultural University Changsha Hunan China
| | - Xinhua Liu
- College of Animal Science and Technology Hunan Agricultural University Changsha Hunan China
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5
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Enriquez‐Urzelai U, Nicieza AG, Montori A, Llorente GA, Urrutia MB. Physiology and acclimation potential are tuned with phenology in larvae of a prolonged breeder amphibian. OIKOS 2021. [DOI: 10.1111/oik.08566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Alfredo G. Nicieza
- Biodiversity Research Inst. (IMIB), Univ. of Oviedo‐Principality of Asturias‐CSIC Oviedo Spain
- Ecology Unit, Dept of Biology of Organisms and Systems, Univ. of Oviedo Oviedo Spain
| | - Albert Montori
- CREAC, Centre de Recerca i Educació Ambiental de Calafell, Calafell Barcelona Spain
| | - Gustavo A. Llorente
- Dept of Evolutionary Biology, Ecology and Environmental Sciences and Inst. de Recerca de la Biodiversitat (IRBIO), Faculty of Biology, Univ. of Barcelona Barcelona Spain
| | - Miren Bego Urrutia
- Depto de Genética, Antropología Física y Fisiología Animal, Univ. del País Vasco/Euskal Herriko Unibertsitatea Bilbao Spain
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6
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Urbina J, Bredeweg EM, Blaustein AR, Garcia TS. Direct and Latent Effects of Pathogen Exposure Across Native and Invasive Amphibian Life Stages. Front Vet Sci 2021; 8:732993. [PMID: 34778428 PMCID: PMC8585985 DOI: 10.3389/fvets.2021.732993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 09/28/2021] [Indexed: 11/13/2022] Open
Abstract
Emerging infectious diseases are one of the multiple factors contributing to the current "biodiversity crisis". As part of the worldwide biodiversity crisis, amphibian populations are declining globally. Chytridiomycosis, an emerging infectious disease, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is a major cause of amphibian population declines. This fungus primarily affects keratinized structures in larval, juvenile, and adult amphibians as well as heart function. However, we know little about how Bd can impact embryos as well as potential latent effects of Bd exposure over ontogeny. Using two different Bd strains and multiple exposure times, we examined the effects of Bd exposure in Pacific chorus frog (Pseudacris regilla), Western toad (Anaxyrus boreas) and American bullfrog (Lithobates catesbeianus) life stages. Using a factorial experimental design, embryos of these three species were exposed to Bd at early and late embryonic stages, with some individuals re-exposed after hatching. Embryonic Bd exposure resulted in differential survival as a function of host species, Bd strain and timing of exposure. P. regilla experienced embryonic mortality when exposed during later developmental stages to one Bd strain. There were no differences across the treatments in embryonic mortality of A. boreas and embryonic mortality of L. catesbeianus occurred in all Bd exposure treatments. We detected latent effects in A. boreas and L. catesbeianus larvae, as mortality increased when individuals had been exposed to any of the Bd strains during the embryonic stage. We also detected direct effects on larval mortality in all three anuran species as a function of Bd strain, and when individuals were double exposed (late in the embryonic stage and again as larvae). Our results suggest that exposure to Bd can directly affect embryo survival and has direct and latent effects on larvae survival of both native and invasive species. However, these impacts were highly context dependent, with timing of exposure and Bd strain influencing the severity of the effects.
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Affiliation(s)
- Jenny Urbina
- Environmental Sciences Graduate Program, Oregon State University, Corvallis, OR, United States
| | - Evan M Bredeweg
- Department of Fisheries, Wildlife and Conservation Sciences, Oregon State University, Corvallis, OR, United States
| | - Andrew R Blaustein
- Department of Integrative Biology, Oregon State University, Corvallis, OR, United States
| | - Tiffany S Garcia
- Department of Fisheries, Wildlife and Conservation Sciences, Oregon State University, Corvallis, OR, United States
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7
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Pu YC, Wang R, Liu HH, Lu SP, Tang FX, Hou YM. Immunosenescence along with direct physiological allocation trade-offs between life history and immunity in the red palm weevil Rhynchophorus ferrugineus. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2021; 123:104143. [PMID: 34051204 DOI: 10.1016/j.dci.2021.104143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 05/19/2021] [Accepted: 05/22/2021] [Indexed: 06/12/2023]
Abstract
Recent works have generally indicated that insects exhibit two immune response strategies: external and internal immune defense. However, the immune-related trade-offs and physiological regulatory mechanisms in red palm weevil, a major invasive pest, remain unclear. Based on postinfection survivorship experiments, we initially measured baseline constitutive external immunity (antibacterial activity of external secretions) and internal immunity (phenoloxidase and antibacterial activity of hemolymph) in uninfected individuals. Then, we challenged the individual immune system and examined subsequent investment in immune function. Our data showed that multiple factors (instar, age, sex, mating status, immune treatment) interacted to affect immune components and infection outcomes, but the magnitude and nature of the impact varied in each case. Although immune senescence is a common phenomenon in which immune function decreases with age, different components of the immune system changed differentially. Notably, mating activity may impose an immunity-related cost, with some evidence of sexual dimorphism and age-associated differences. Finally, parameters related to life-history traits usually decreased temporarily because of increased immunity, suggesting that the ultimate consequences of immune function fitness may be physiologically traded off with other fitness aspects, including growth, development, mating, reproduction, and longevity. These results reveal the complex factors that impact immunity as well as the physiological regulation of individual immunity, which may determine the evolution and outcome of immune senescence and trade-offs.
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Affiliation(s)
- Yu-Chen Pu
- School of Biological Science and Biotechnology, Minnan Normal University, Zhangzhou, Fujian, 363000, China; State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China; Fujian Provincial Key Laboratory of Insect Ecology, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Rui Wang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China; Fujian Provincial Key Laboratory of Insect Ecology, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Hui-Hui Liu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China; Fujian Provincial Key Laboratory of Insect Ecology, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Sheng-Ping Lu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China; Fujian Provincial Key Laboratory of Insect Ecology, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - Fan-Xi Tang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China; Fujian Provincial Key Laboratory of Insect Ecology, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
| | - You-Ming Hou
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China; Fujian Provincial Key Laboratory of Insect Ecology, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China.
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8
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Kirschman LJ, Khadjinova A, Ireland K, Milligan-Myhre KC. Early life disruption of the microbiota affects organ development and cytokine gene expression in threespine stickleback. Integr Comp Biol 2020; 63:icaa136. [PMID: 32970813 PMCID: PMC10388389 DOI: 10.1093/icb/icaa136] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 09/04/2020] [Accepted: 09/08/2020] [Indexed: 12/20/2022] Open
Abstract
The microbiota that inhabits vertebrates exerts strong effects on host physiology and can be crucial to the development of a normal phenotype. This includes development of the immune system, somatic growth and maintenance, and morphogenesis. However, the genetic background of the host can also affect these life history traits. To this end, we investigated the effects of the microbiota on growth, development, and immune gene expression on two populations of threespine stickleback (Gasterosteus aculeatus), one anadromous and one freshwater. We tested the hypotheses that microbial colonization and the genetic background of the host would affect survival, cytokine gene expression, growth, and development. We raised in vitro crosses of stickleback larvae with and without conventional microbiota. We then exposed all these treatments to Vibrio anguillarum, a potential fish pathogen, in a full factorial design. We found stickleback raised without conventional microbiota had smaller swim bladders relative to those raised with conventional microbiota. Stickleback raised with conventional microbiota exhibited small increases in cytokine gene expression. We found no differences in growth or survival regardless of treatment. These results are consistent with other investigations that show microbiota disruption, in early life, can alter host organ and tissue development and immune responses.
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Affiliation(s)
- Lucas J Kirschman
- Department Biology, Southeast Missouri University, 1 University Plaza, Cape Girardeau, MO 63701, USA
| | | | - Kelly Ireland
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508, USA
| | - Kathryn C Milligan-Myhre
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508, USA
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269-3125, USA
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9
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Bienentreu JF, Lesbarrères D. Amphibian Disease Ecology: Are We Just Scratching the Surface? HERPETOLOGICA 2020. [DOI: 10.1655/0018-0831-76.2.153] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
| | - David Lesbarrères
- Department of Biology, Laurentian University, Sudbury, ON P3E 2C6, Canada
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10
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Barnhart KL, Bletz MC, LaBumbard BC, Tokash-Peters AG, Gabor CR, Woodhams DC. Batrachochytrium salamandrivorans ELICITS ACUTE STRESS RESPONSE IN SPOTTED SALAMANDERS BUT NOT INFECTION OR MORTALITY. Anim Conserv 2020; 23:533-546. [PMID: 33071596 DOI: 10.1111/acv.12565] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The emerging fungal pathogen Batrachochytrium salamandrivorans (Bsal) is a major threat to amphibian species worldwide with potential to infect many species if it invades salamander biodiversity hotspots in the Americas. Bsal can cause the disease chytridiomycosis, and it is important to assess the risk of Bsal-induced chytridiomycosis to species in North America. We evaluated the susceptibility to Bsal of the common and widespread spotted salamander, Ambystoma maculatum, across life history stages and monitored the effect of Bsal exposure on growth rate and response of the stress hormone, corticosterone. We conclude that spotted salamanders appear resistant to Bsal because they showed no indication of disease or infection, and experienced minor effects on growth upon exposure. While we focused on a single population for this study, results were consistent across conditions of exposure including high or repeated doses of Bsal, life-stage at exposure, environmental conditions including two temperatures and two substrates, and promoting pathogen infectivity by conditioning Bsal cultures with thyroid hormone. Exposure to high levels of Bsal elicited an acute but not chronic increase in corticosterone in spotted salamanders, and reduced growth. We hypothesize that the early acute increase in corticosterone facilitated mounting an immune response to the pathogen, perhaps through immunoredistribution to the skin, but further study is needed to determine immune responses to Bsal. These results will contribute to development of appropriate Bsal management plans to conserve species at risk of emerging disease.
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Affiliation(s)
- Kelly L Barnhart
- University of Massachusetts Boston, Department of Biology, 100 William T Morrissey Blvd, Boston, MA 02125
| | - Molly C Bletz
- University of Massachusetts Boston, Department of Biology, 100 William T Morrissey Blvd, Boston, MA 02125
| | - Brandon C LaBumbard
- University of Massachusetts Boston, Department of Biology, 100 William T Morrissey Blvd, Boston, MA 02125
| | - Amanda G Tokash-Peters
- University of Massachusetts Boston, Department of Biology, 100 William T Morrissey Blvd, Boston, MA 02125
| | - Caitlin R Gabor
- Texas State University, Department of Biology, 601 University Drive, San Marcos, TX 78666
| | - Douglas C Woodhams
- University of Massachusetts Boston, Department of Biology, 100 William T Morrissey Blvd, Boston, MA 02125
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11
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Hammond TT, Blackwood PE, Shablin SA, Richards-Zawacki CL. Relationships between glucocorticoids and infection with Batrachochytrium dendrobatidis in three amphibian species. Gen Comp Endocrinol 2020; 285:113269. [PMID: 31493395 DOI: 10.1016/j.ygcen.2019.113269] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Revised: 08/20/2019] [Accepted: 09/03/2019] [Indexed: 11/19/2022]
Abstract
It is often hypothesized that organisms exposed to environmental change may experience physiological stress, which could reduce individual quality and make them more susceptible to disease. Amphibians are amongst the most threatened taxa, particularly in the context of disease, but relatively few studies explore links between stress and disease in amphibian species. Here, we use the fungal pathogen Batrachochytrium dendrobatidis (Bd) and amphibians as an example to explore relationships between disease and glucocorticoids (GCs), metabolic hormones that comprise one important component of the stress response. While previous work is limited, it has largely identified positive relationships between GCs and Bd-infection. However, the causality remains unclear and few studies have integrated both baseline (GC release that is related to standard, physiological functioning) and stress-induced (GC release in response to an acute stressor) measures of GCs. Here, we examine salivary corticosterone before and after exposure to a stressor, in both field and captive settings. We present results for Bd-infected and uninfected individuals of three amphibian species with differential susceptibilities to this pathogen (Rana catesbeiana, R. clamitans, and R. sylvatica). We hypothesized that prior to stress, baseline GCs would be higher in Bd-infected animals, particularly in more Bd-susceptible species. We also expected that after exposure to a stressor, stress-induced GCs would be lower in Bd-infected animals. These species exhibited significant interspecific differences in baseline and stress induced corticosterone, though other variables like sex, body size, and day of year were usually not predictive of corticosterone. In contrast to most previous work, we found no relationships between Bd and corticosterone for two species (R. catesbeiana and R. clamitans), and in the least Bd-tolerant species (R. sylvatica) animals exhibited context-dependent differences in relationships between Bd infection and corticosterone: Bd-positive R. sylvatica had significantly lower baseline and stress-induced corticosterone, with this pattern being stronger in the field than in captivity. These results were surprising, as past work in other species has more often found elevated GCs in Bd-positive animals, a pattern that aligns with well-documented relationships between chronically high GCs, reduced individual quality, and immunosuppression. This work highlights the potential relevance of GCs to disease susceptibility in the context of amphibian declines, while underscoring the importance of characterizing these relationships in diverse contexts.
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Affiliation(s)
- Talisin T Hammond
- Department of Biological Sciences, University of Pittsburgh, 105 Clapp Hall, 5th Ave at Ruskin Ave, Pittsburgh, PA 15260, USA; San Diego Zoo Institute for Conservation Research, 15600 San Pasqual Valley Rd., Escondido, CA 92027, USA.
| | - Paradyse E Blackwood
- Department of Biological Sciences, University of Pittsburgh, 105 Clapp Hall, 5th Ave at Ruskin Ave, Pittsburgh, PA 15260, USA
| | - Samantha A Shablin
- Department of Biological Sciences, University of Pittsburgh, 105 Clapp Hall, 5th Ave at Ruskin Ave, Pittsburgh, PA 15260, USA
| | - Corinne L Richards-Zawacki
- Department of Biological Sciences, University of Pittsburgh, 105 Clapp Hall, 5th Ave at Ruskin Ave, Pittsburgh, PA 15260, USA
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12
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Bramke K, Müller U, McMahon DP, Rolff J. Exposure of Larvae of the Solitary Bee Osmia bicornis to the Honey Bee Pathogen Nosema ceranae Affects Life History. INSECTS 2019; 10:E380. [PMID: 31683739 PMCID: PMC6921066 DOI: 10.3390/insects10110380] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 10/24/2019] [Accepted: 10/28/2019] [Indexed: 01/16/2023]
Abstract
Wild bees are important pollinators of wild plants and agricultural crops and they are threatened by several environmental stressors including emerging pathogens. Honey bees have been suggested as a potential source of pathogen spillover. One prevalent pathogen that has recently emerged as a honey bee disease is the microsporidian Nosema ceranae. While the impacts of N. ceranae in honey bees are well documented, virtually nothing is known about its effects in solitary wild bees. The solitary mason bee Osmia bicornis is a common pollinator in orchards and amenable to commercial management. Here, we experimentally exposed larvae of O. bicornis to food contaminated with N. ceranae and document spore presence during larval development. We measured mortality, growth parameters, and timing of pupation in a semi-field experiment. Hatched individuals were assessed for physiological state including fat body mass, wing muscle mass, and body size. We recorded higher mortality in the viable-spore-exposed group but could only detect a low number of spores among the individuals of this treatment. Viable-spore-treated individuals with higher head capsule width had a delayed pupation start. No impact on the physiological status could be detected in hatched imagines. Although we did not find overt evidence of O. bicornis infection, our findings indicate that exposure of larvae to viable N. ceranae spores could affect bee development.
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Affiliation(s)
- Kathrin Bramke
- Institut für Biologie, Universität Berlin, 14195 Berlin, Germany.
| | - Uta Müller
- Institut für Biologie, Universität Berlin, 14195 Berlin, Germany.
| | - Dino P McMahon
- Institut für Biologie, Universität Berlin, 14195 Berlin, Germany.
- Abteilung 4 Material und Umwelt, Bundesanstalt für Materialforschung und-prüfung (BAM), 12205 Berlin, Germany.
| | - Jens Rolff
- Institut für Biologie, Universität Berlin, 14195 Berlin, Germany.
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13
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An Acute Stress Model in New Zealand White Rabbits Exhibits Altered Immune Response to Infection with West Nile Virus. Pathogens 2019; 8:pathogens8040195. [PMID: 31635289 PMCID: PMC6963736 DOI: 10.3390/pathogens8040195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 10/14/2019] [Accepted: 10/16/2019] [Indexed: 12/17/2022] Open
Abstract
The immune competence of an individual is a major determinant of morbidity in West Nile virus (WNV)-infection. Previously, we showed that immunocompetent New Zealand White rabbits (NZWRs; Oryctolagus cuniculus) are phenotypically resistant to WNV-induced disease, thus presenting a suitable model for study of virus-control mechanisms. The current study used corticosteroid-treated NZWRs to model acute “stress”-related immunosuppression. Maximal effects on immune parameters were observed on day 3 post dexamethasone-treatment (pdt). However, contrary to our hypothesis, intradermal WNV challenge at this time pdt produced significantly lower viremia 1 day post-infection (dpi) compared to untreated controls, suggestive of changes to antiviral control mechanisms. To examine this further, RNAseq was performed on RNA extracted from draining lymph node—the first site of virus replication and immune detection. Unaffected by dexamethasone-treatment, an early antiviral response, primarily via interferon (IFN)-I, and induction of a range of known and novel IFN-stimulated genes, was observed. However, treatment was associated with expression of a different repertoire of IFN-α-21-like and IFN-ω-1-like subtypes on 1 dpi, which may have driven the different chemokine response on 3 dpi. Ongoing expression of Toll-like receptor-3 and transmembrane protein-173/STING likely contributed to signaling of the treatment-independent IFN-I response. Two novel genes (putative HERC6 and IFIT1B genes), and the SLC16A5 gene were also highlighted as important component of the transcriptomic response. Therefore, the current study shows that rabbits are capable of restricting WNV replication and dissemination by known and novel robust antiviral mechanisms despite environmental challenges such as stress.
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The Costs of Living Together: Immune Responses to the Microbiota and Chronic Gut Inflammation. Appl Environ Microbiol 2019; 85:AEM.02147-18. [PMID: 30530709 DOI: 10.1128/aem.02147-18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
While the vertebrate microbiota is critical to the normal function of many host traits, hosts may expend a large amount of energy to constrain and interface with their microbiota via their immune system to avoid the high fitness costs associated with gut dysbiosis, pathobionts, and opportunistic pathogens. All jawed vertebrates share mucosal immunity dedicated to isolating the microbiota, and a breakdown of this system can result in chronic gut inflammation. In humans, chronic gut inflammation negatively affects growth and development. There is little information available on the prevalence of chronic gut inflammation in wild animals, but given that animals with different life histories emphasize different immune responses, it follows that wild animals may vary in their susceptibility to chronic gut inflammation, and most animals will experience signaling that can lead to this state. These can be top-down signals originating from sources like the central nervous system or bottom-up signals originating from changes in the gut microbiota. The sources of these signals might include stress, developmental transitions, food restriction, and dietary shifts. Here, we briefly discuss host-microbiota interactions from the perspective of life history theory and ecoimmunology, focusing on the mucosal immune system and chronic gut inflammation. We also include future directions for research and the tools necessary to investigate them.
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Schoenle LA, Zimmer C, Vitousek MN. Understanding Context Dependence in Glucocorticoid-Fitness Relationships: The Role of the Nature of the Challenge, the Intensity and Frequency of Stressors, and Life History. Integr Comp Biol 2019; 58:777-789. [PMID: 29889246 DOI: 10.1093/icb/icy046] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
It has been well-established that there is variation in the strength and direction of the relationship between circulating glucocorticoids (GCs) and fitness. When studies demonstrate such variation or the direction of the GC-fitness relationship is unexpected, the results are often attributed to context-dependency. However, descriptors of context can be vague (e.g., "environmental context") and few studies explicitly test how the optimal hypothalamic-pituitary-adrenal (HPA) axis response to stressors varies across specific contexts. Although existing hypotheses create a strong foundation for understanding GC-fitness relationships, many do not provide explicit predictions of how, when, and why the relationships will change. Here, we discuss three broad factors which we expect to shape the relationships between HPA axis activity and fitness metrics: (1) whether the HPA axis-mediated response matches the challenge, (2) the intensity and frequency of challenges, and (3) life history. We also make predictions for how these factors might affect GC-fitness relationships and discuss ways to test these predictions. Observational studies, experimental manipulations of context, and large-scale cross-species comparisons will be critical to understanding the observed variation in GC-fitness relationships.
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Affiliation(s)
- Laura A Schoenle
- Department of Global Health, University of South Florida, Tampa, FL 33620, USA.,Department of Biology, Hamilton College, Clinton, NY 13323, USA
| | - Cedric Zimmer
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - Maren N Vitousek
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA.,Cornell Lab of Ornithology, Ithaca, NY 14850, USA
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Warne RW, Kirschman L, Zeglin L. Manipulation of gut microbiota during critical developmental windows affects host physiological performance and disease susceptibility across ontogeny. J Anim Ecol 2019; 88:845-856. [PMID: 30828805 DOI: 10.1111/1365-2656.12973] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 01/17/2019] [Indexed: 11/29/2022]
Abstract
Colonization of gut microbiomes during early life can shape metabolism and immunity of adult animals. However, most data are derived from antibiotic-treated or germ-free laboratory mammals. Furthermore, few studies have explored how microbial colonization during critical windows influences a suite of other fitness-related traits in wild animals. This study tested whether hatching constitutes a critical developmental window for gut microbiome colonization in wild-caught amphibians and whether perturbations to gut microbiota at hatching shape fitness-related traits of larval growth, metabolism, metamorphosis and disease susceptibility. We sterilized wood frog eggs and then inoculated them with microbes from differing sources, including from another species (bullfrogs) that differ in disease resistance and life history. We measured development, growth and metabolic rates through metamorphosis among individuals from each microbial treatment. A separate group was exposed to an LD50 dose of ranavirus-an emerging disease-to test for microbiome effects on disease susceptibility. We also quantified rates of deformities to test for microbial treatment effects on overall health. Manipulation of microbiota on eggs altered the trajectory of gut microbiome communities across larval ontogeny, though disruption appeared to be transitory. While microbiome structure converged among the treatments by metamorphosis, the effects of disruption on host phenotypes persisted. Larvae inoculated with the bullfrog gut microbiota exhibited accelerated growth and development rates compared to controls. By contrast, sterilized larvae maintained in sterile water for several days after hatching exhibited greater disruption to their gut microbiota across ontogeny, as well as altered metabolism, more tail deformities, and were more likely to die when exposed to an LD50 dose of ranavirus compared to the other treatments. These results suggest perturbations to the microbiota during critical developmental windows can alter the trajectory of the gut microbiome, and have long-term effects on fitness-related traits in larval amphibians. These results suggest that explicit tests of how changes in the composition and abundance of the microbial community shape phenotypes across ontogeny in amphibians could shed light on host-microbe interactions in wildlife, as well as inform conservation efforts to mitigate emerging diseases.
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Affiliation(s)
- Robin W Warne
- Department of Zoology, Southern Illinois University, Carbondale, Illinois
| | - Lucas Kirschman
- Department of Zoology, Southern Illinois University, Carbondale, Illinois
| | - Lydia Zeglin
- Biology Department, Kansas State University, Manhattan, Kansas
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Waye HL, Dolan PC, Hernandez A. White Blood Cell Profiles in Long-Term Captive and Recently Captured Eastern Tiger Salamanders (Ambystoma tigrinum). COPEIA 2019. [DOI: 10.1643/cp-18-126] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Heather L. Waye
- University of Minnesota Morris, Morris, Minnesota 56267; (HLW) . Send reprint requests to HLW
| | - Peter C. Dolan
- University of Minnesota Morris, Morris, Minnesota 56267; (HLW) . Send reprint requests to HLW
| | - Alexis Hernandez
- University of Minnesota Morris, Morris, Minnesota 56267; (HLW) . Send reprint requests to HLW
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Seasonal dynamics and potential drivers of ranavirus epidemics in wood frog populations. Oecologia 2018; 188:1253-1262. [DOI: 10.1007/s00442-018-4274-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 10/14/2018] [Indexed: 12/22/2022]
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