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Hawley L, Smalling KL, Glaberman S. Critical review of the phytohemagglutinin assay for assessing amphibian immunity. CONSERVATION PHYSIOLOGY 2023; 11:coad090. [PMID: 38090122 PMCID: PMC10714196 DOI: 10.1093/conphys/coad090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 09/15/2023] [Accepted: 10/26/2023] [Indexed: 04/26/2024]
Abstract
Infectious diseases are a major driver of the global amphibian decline. In addition, many factors, including genetics, stress, pollution, and climate change can influence the response to pathogens. Therefore, it is important to be able to evaluate amphibian immunity in the laboratory and in the field. The phytohemagglutinin (PHA) assay is an inexpensive and relatively non-invasive tool that has been used extensively to assess immunocompetence, especially in birds, and more recently in amphibians. However, there is substantial variation in experimental methodology among amphibian PHA studies in terms of species and life stages, PHA doses and injection sites, and use of experimental controls. Here, we compile and compare all known PHA studies in amphibians to identify knowledge gaps and develop best practices for future work. We found that research has only been conducted on a limited number of species, which may not reflect the diversity of amphibians. There is also a lack of validation studies in most species, so that doses and timing of PHA injection and subsequent swelling measurements may not effectively evaluate immunocompetence. Based on these and other findings, we put forward a set of recommendations to make future PHA studies more consistent and improve the ability to utilize this assay in wild populations, where immune surveillance is greatly needed.
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Affiliation(s)
- Lauren Hawley
- Department of Environmental Science and Policy, George Mason University, Fairfax, VA, USA
| | - Kelly L Smalling
- New Jersey Water Science Center, U.S. Geological Survey, Lawrenceville, NJ, USA
| | - Scott Glaberman
- Department of Environmental Science and Policy, George Mason University, Fairfax, VA, USA
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2
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Rollins-Smith LA. The importance of antimicrobial peptides (AMPs) in amphibian skin defense. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2023; 142:104657. [PMID: 36754220 DOI: 10.1016/j.dci.2023.104657] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 01/20/2023] [Accepted: 02/04/2023] [Indexed: 06/18/2023]
Abstract
Antimicrobial peptides (AMPs) are produced for defense in nearly all taxa from simple bacteria to complex mammalian species. Some amphibian families have developed this defensive strategy to a high level of sophistication by loading the AMPs into specialized granular glands within the dermis. Enervated by the sympathetic nervous system, the granular glands are poised to deliver an array of AMPs to cleanse the wound and facilitate healing. There have been a number of excellent review publications in recent years that describe amphibian AMPs with an emphasis on their possible uses for human medicine. Instead, my aim here is to review what is known about the nature of amphibian AMPs, the diversity of amphibian AMPs, regulation of their production, and to provide the accumulated evidence that they do, indeed, play an important role in the protection of amphibian skin, vital for survival. While much has been learned about amphibian AMPs, there are still important gaps in our understanding of peptide synthesis, storage, and functions.
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Affiliation(s)
- Louise A Rollins-Smith
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA; Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN, USA; Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA.
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3
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Hardman RH, Reinert LK, Irwin KJ, Oziminski K, Rollins-Smith L, Miller DL. Disease state associated with chronic toe lesions in hellbenders may alter anti-chytrid skin defenses. Sci Rep 2023; 13:1982. [PMID: 36737574 PMCID: PMC9898527 DOI: 10.1038/s41598-023-28334-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 01/17/2023] [Indexed: 02/05/2023] Open
Abstract
Hellbenders (Cryptobranchus alleganiensis) are large, aquatic salamanders from the eastern United States. Both subspecies, eastern and Ozark hellbenders, have experienced declines resulting in federal listing of Ozark hellbenders. The globally distributed chytrid fungus, Batrachochytrium dendrobatidis (Bd) has been detected in both subspecies, and Batrachochytrium salamandrivorans (Bsal) poses a new threat if introduced into North America. Ozark hellbenders also suffer a high prevalence of toe lesions of unknown etiology, with changes in host immunocompetence hypothesized to contribute. Antimicrobial peptides (AMPs) secreted from dermal granular glands may play a role in hellbender health. We collected skin secretions from free-ranging hellbenders and enriched them for small cationic peptides used for growth inhibition assays against Bd and Bsal. Generalized linear mixed models revealed the presence of active toe lesions as the strongest and only significant predictor of decreased Bd inhibition by skin peptides. We also found skin secretions were more inhibitory of Bsal than Bd. MALDI-TOF mass spectrometry revealed candidate peptides responsible for anti-chytrid activity. Results support the hypothesis that hellbender skin secretions are important for innate immunity against chytrid pathogens, and decreased production or release of skin peptides may be linked to other sub-lethal effects of disease associated with toe lesions.
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Affiliation(s)
- Rebecca H Hardman
- Department of Biomedical and Diagnostic Sciences, University of Tennessee College of Veterinary Medicine, Knoxville, TN, 37996, USA. .,Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, St. Petersburg, FL, 33701, USA.
| | - Laura K Reinert
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Kelly J Irwin
- Arkansas Game and Fish Commission, Benton, AR, 72015, USA
| | - Kendall Oziminski
- Department of Biomedical and Diagnostic Sciences, University of Tennessee College of Veterinary Medicine, Knoxville, TN, 37996, USA
| | - Louise Rollins-Smith
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Debra L Miller
- Department of Biomedical and Diagnostic Sciences, University of Tennessee College of Veterinary Medicine, Knoxville, TN, 37996, USA.,School of Natural of Resources, University of Tennessee, Knoxville, Tennessee, 37996, USA
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4
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Besedin D, Turner BJ, Deo P, Lopes MDB, Williams CR. Effect of captivity and water salinity on culture-dependent frog skin microbiota and Batrachochytrium dendrobatidis ( Bd) infection. T ROY SOC SOUTH AUST 2022. [DOI: 10.1080/03721426.2022.2086358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Darislav Besedin
- UniSA Clinical and Health Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - Brandon J. Turner
- UniSA Clinical and Health Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - Permal Deo
- UniSA Clinical and Health Sciences, University of South Australia, Adelaide, South Australia, Australia
- Health and Biomedical Innovation, UniSA Clinical and Health Science, University of South Australia, Adelaide, South Australia, Australia
| | - Miguel De Barros Lopes
- UniSA Clinical and Health Sciences, University of South Australia, Adelaide, South Australia, Australia
- Health and Biomedical Innovation, UniSA Clinical and Health Science, University of South Australia, Adelaide, South Australia, Australia
| | - Craig R. Williams
- UniSA Clinical and Health Sciences, University of South Australia, Adelaide, South Australia, Australia
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5
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Garnham JI, Bower DS, Stockwell MP, Pickett EJ, Pollard CJ, Clulow J, Mahony MJ. Seasonal variation in the prevalence of a fungal pathogen and unexpected clearance from infection in a susceptible frog species. DISEASES OF AQUATIC ORGANISMS 2022; 148:1-11. [PMID: 35142293 DOI: 10.3354/dao03628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) causes the disease chytridiomycosis, which is a primary driver for amphibian population declines and extinctions worldwide. For highly susceptible species, such as the green and golden bell frog Litoria aurea, large numbers of Bd-related mortalities are thought to occur during the colder season (winter), when low temperatures favour the growth of the pathogen. However, extant L. aurea populations are persisting with Bd. We measured Bd prevalence and infection levels of wild L. aurea using capture-mark-recapture and radio-tracking methods. Using this information, we sought to determine host and environmental correlates of Bd prevalence and infection load. Mean ± SE infection load was higher in frogs sampled in autumn (431.5 ± 310.4 genomic equivalents; GE) and winter (1147.5 ± 735.8 GE), compared to spring (21.8 ± 19.3 GE) and summer (0.9 ± 0.8 GE). Furthermore, prevalence of Bd infection in L. aurea was highest in winter (43.6%; 95% CI 33.1-54.7%) and lowest in summer (11.2%; 95% CI 6.8-17.9%). Both prevalence and infection load decreased with increasing temperature. Seven frogs cleared their fungal infection during the coolest months when Bd prevalence was highest; however, these clearances were not permanent, as 5 frogs became infected again. Understanding the factors that allow amphibians to clear their Bd infections when temperatures are optimal for Bd growth presents the potential for manipulating such factors and provides an important step in future research.
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Affiliation(s)
- James I Garnham
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales 2308, Australia
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6
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An Evaluation of Immersive and Handling Methods for Collecting Salamander Skin Peptides. J HERPETOL 2021. [DOI: 10.1670/20-122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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7
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Ujszegi J, Ludányi K, Móricz ÁM, Krüzselyi D, Drahos L, Drexler T, Németh MZ, Vörös J, Garner TWJ, Hettyey A. Exposure to Batrachochytrium dendrobatidis affects chemical defences in two anuran amphibians, Rana dalmatina and Bufo bufo. BMC Ecol Evol 2021; 21:135. [PMID: 34217227 PMCID: PMC8254444 DOI: 10.1186/s12862-021-01867-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 06/23/2021] [Indexed: 11/03/2022] Open
Abstract
Background Batrachochytrium dendrobatidis (Bd) is the causative agent of chytridiomycosis, one of the major causes of worldwide amphibian biodiversity loss. Many amphibians exhibit skin-based chemical defences, which may play an important role against invading pathogens, but whether the synthesis of these chemical compounds is enhanced or suppressed in the presence of pathogens is largely unknown. Here we investigated direct and indirect effects of larval exposure to the globally distributed and highly virulent Bd-GPL strain on skin secreted chemical defences and life history traits during early ontogeny of agile frogs (Rana dalmatina) and common toads (Bufo bufo). Results Exposure to Bd during the larval stage did not result in enhanced synthesis of the antimicrobial peptide Brevinin-1 Da in R. dalmatina tadpoles or in increased production of bufadienolides in B. bufo tadpoles. However, exposure to Bd during the larval stage had a carry-over effect reaching beyond metamorphosis: both R. dalmatina and B. bufo froglets contained smaller quantities of defensive chemicals than their Bd-naïve conspecifics in the control treatment. Prevalence of Bd and infection intensities were very low in both larvae and metamorphs of R. dalmatina, while in B. bufo we observed high Bd prevalence and infection intensities, especially in metamorphs. At the same time, we did not find a significant effect of Bd-exposure on body mass or development rate in larvae or metamorphs in either species. Conclusions The lack of detrimental effect of Bd-exposure on life history traits, even parallel with high infection intensities in the case of B. bufo individuals, is surprising and suggests high tolerance of local populations of these two species against Bd. However, the lowered quantity of defensive chemicals may compromise antimicrobial and antipredatory defences of froglets, which may ultimately contribute to population declines also in the absence of conspicuous mass-mortality events.
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Affiliation(s)
- János Ujszegi
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Herman Ottó út 15, Budapest, 1022, Hungary.
| | - Krisztina Ludányi
- Department of Pharmaceutics, Faculty of Pharmacy, Semmelweis University, Hőgyes Endre utca 7, Budapest, 1092, Hungary
| | - Ágnes M Móricz
- Department of Pathophysiology, Plant Protection Institute, Centre for Agricultural Research, Herman Ottó út 15, Budapest, 1022, Hungary
| | - Dániel Krüzselyi
- Department of Pathophysiology, Plant Protection Institute, Centre for Agricultural Research, Herman Ottó út 15, Budapest, 1022, Hungary
| | - László Drahos
- MS Proteomics Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary
| | - Tamás Drexler
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Herman Ottó út 15, Budapest, 1022, Hungary.,Department of Ecology, Institute for Biology, University of Veterinary Medicine, Rottenbiller utca 50, Budapest, 1077, Hungary
| | - Márk Z Németh
- Department of Plant Pathology, Plant Protection Institute, Centre for Agricultural Research, Herman Ottó út 15, Budapest, 1022, Hungary
| | - Judit Vörös
- Department of Zoology, Hungarian Natural History Museum, Baross street 13, Budapest, 1088, Hungary
| | - Trenton W J Garner
- Institute of Zoology, Zoological Society of London, Regent's Park, London, NW1 4RY, UK.,Unit for Environmental Sciences and Management, North-West University, Potchefstroom, 2520, South Africa
| | - Attila Hettyey
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Herman Ottó út 15, Budapest, 1022, Hungary.,Department of Ecology, Institute for Biology, University of Veterinary Medicine, Rottenbiller utca 50, Budapest, 1077, Hungary
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8
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Venesky MD, Laskey CA. Infection with Batrachochytrium dendrobatidis reduces salamander capacity to mount a cell-mediated immune response. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2021; 337:273-281. [PMID: 34102032 DOI: 10.1002/jez.2497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 05/07/2021] [Accepted: 05/14/2021] [Indexed: 11/06/2022]
Abstract
The vertebrate immune system is a costly defense system that is responsible for preventing and eliminating parasites and pathogens. Theory predicts that hosts experience tradeoffs associated with immune deployment and other physiological functions. Although empirical evidence for immune-physiology tradeoffs are well documented in the literature, fewer studies have examined tradeoffs within the immune system in wild vertebrates. We explored the topic of concomitant immune challenges in amphibians by exposing salamanders (Plethodon cinereus) to a fungal pathogen Batrachochytrium dendrobatidis (hereafter "Bd") and then to phytohemagglutinin (hereafter "PHA"). We measured Bd infection using quantitative PCR and used measurements of the tail thickness at the PHA injection site as an estimate of skin swelling. We tested whether Bd reduced the salamander's capacity to mount an immune response towards PHA or whether Bd would stimulate immune activity and thereby increase the response towards PHA. Salamanders that were infected with Bd had a reduced skin-swelling when injected with PHA compared to noninfected salamanders, a result that is consistent with the hypothesis that Bd-infected salamanders have lower immunocompetence than noninfected salamanders. We also found that PHA-induced swelling response was negatively associated with Bd infection abundance (i.e., the infection burden of all exposed salamanders, including those that were exposed but not infected), indicating that salamanders with a higher infection abundance had the lowest swelling response to PHA. Our results suggest that individuals of P. cinereus might experience an energetic tradeoff between successfully fighting off Bd and mounting an immune response towards PHA.
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Affiliation(s)
- Matthew D Venesky
- Department of Biology, Allegheny College, Meadville, Pennsylvania, USA
| | - Corey A Laskey
- Department of Biology, Allegheny College, Meadville, Pennsylvania, USA
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9
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Pereira KE, Woodley SK. Skin defenses of North American salamanders against a deadly salamander fungus. Anim Conserv 2021. [DOI: 10.1111/acv.12666] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- K. E. Pereira
- Department of Biological Sciences Duquesne University Pittsburgh PA USA
| | - S. K. Woodley
- Department of Biological Sciences Duquesne University Pittsburgh PA USA
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10
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Brannelly LA, McCallum HI, Grogan LF, Briggs CJ, Ribas MP, Hollanders M, Sasso T, Familiar López M, Newell DA, Kilpatrick AM. Mechanisms underlying host persistence following amphibian disease emergence determine appropriate management strategies. Ecol Lett 2020; 24:130-148. [PMID: 33067922 DOI: 10.1111/ele.13621] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 06/18/2020] [Accepted: 09/08/2020] [Indexed: 12/19/2022]
Abstract
Emerging infectious diseases have caused many species declines, changes in communities and even extinctions. There are also many species that persist following devastating declines due to disease. The broad mechanisms that enable host persistence following declines include evolution of resistance or tolerance, changes in immunity and behaviour, compensatory recruitment, pathogen attenuation, environmental refugia, density-dependent transmission and changes in community composition. Here we examine the case of chytridiomycosis, the most important wildlife disease of the past century. We review the full breadth of mechanisms allowing host persistence, and synthesise research on host, pathogen, environmental and community factors driving persistence following chytridiomycosis-related declines and overview the current evidence and the information required to support each mechanism. We found that for most species the mechanisms facilitating persistence have not been identified. We illustrate how the mechanisms that drive long-term host population dynamics determine the most effective conservation management strategies. Therefore, understanding mechanisms of host persistence is important because many species continue to be threatened by disease, some of which will require intervention. The conceptual framework we describe is broadly applicable to other novel disease systems.
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Affiliation(s)
- Laura A Brannelly
- Veterinary BioSciences, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Vic, 3030, Australia
| | - Hamish I McCallum
- Environmental Futures Research Institute and School of Environment and Science, Griffith University, Nathan, Qld., 4111, Australia
| | - Laura F Grogan
- Environmental Futures Research Institute and School of Environment and Science, Griffith University, Nathan, Qld., 4111, Australia.,Forest Research Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, NSW, 2480, Australia
| | - Cheryl J Briggs
- Ecology, Evolution and Marine Biology, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Maria P Ribas
- Forest Research Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, NSW, 2480, Australia.,Wildlife Conservation Medicine Research Group, Departament de Medicina i Cirurgia Animals, Universitat Autònoma de Barcelona, Bellaterra, 08193, Spain
| | - Matthijs Hollanders
- Forest Research Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, NSW, 2480, Australia
| | - Thais Sasso
- Environmental Futures Research Institute and School of Environment and Science, Griffith University, Nathan, Qld., 4111, Australia
| | - Mariel Familiar López
- School of Environment and Sciences, Griffith University, Gold Coast, Qld., 4215, Australia
| | - David A Newell
- Forest Research Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, NSW, 2480, Australia
| | - Auston M Kilpatrick
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, 95064, USA
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11
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Loudon AH, Kurtz A, Esposito E, Umile TP, Minbiole KPC, Parfrey LW, Sheafor BA. Columbia spotted frogs (Rana luteiventris) have characteristic skin microbiota that may be shaped by cutaneous skin peptides and the environment. FEMS Microbiol Ecol 2020; 96:5894915. [DOI: 10.1093/femsec/fiaa168] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 08/13/2020] [Indexed: 01/20/2023] Open
Abstract
ABSTRACT
Global amphibian declines due to the fungal pathogen Batrachochytrium dendrobatidis (Bd) have led to questions about how amphibians defend themselves against skin diseases. A total of two amphibian defense mechanisms are antimicrobial peptides (AMPs), a component of amphibian innate immune defense and symbiotic skin bacteria, which can act in synergy. We characterized components of these factors in four populations of Columbia spotted frogs (Rana luteiventris) to investigate their role in disease defense. We surveyed the ability of their AMPs to inhibit Bd, skin bacterial community composition, skin metabolite profiles and presence and intensity of Bd infection. We found that AMPs from R. luteiventris inhibited Bd in bioassays, but inhibition did not correlate with Bd intensity on frogs. R. luteiventris had two prevalent and abundant core bacteria: Rhizobacter and Chryseobacterium. Rhizobacter relative abundance was negatively correlated with AMP's ability to inhibit Bd, but was not associated with Bd status itself. There was no relationship between metabolites and Bd. Bacterial communities and Bd differ by location, which suggests a strong environmental influence. R. luteiventris are dominated by consistent core bacteria, but also house transient bacteria that are site specific. Our emergent hypothesis is that host control and environmental factors shape the microbiota on R. luteiventris.
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Affiliation(s)
- A H Loudon
- Department of Zoology and Biodiversity Centre, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, CA
| | - A Kurtz
- Biology Department, Carroll College, Helena, Montana, 59625-0002, USA
| | - E Esposito
- Biology Department, Carroll College, Helena, Montana, 59625-0002, USA
| | - T P Umile
- Department of Chemistry, Villanova University, Villanova, Pennsylvania, 19085-1603, USA
| | - K P C Minbiole
- Department of Chemistry, Villanova University, Villanova, Pennsylvania, 19085-1603, USA
| | - L W Parfrey
- Department of Zoology and Biodiversity Centre, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, CA
- Department of Botany, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, CA
| | - B A Sheafor
- Biology Department, Carroll College, Helena, Montana, 59625-0002, USA
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12
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Rollins-Smith LA. Global Amphibian Declines, Disease, and the Ongoing Battle between Batrachochytrium Fungi and the Immune System. HERPETOLOGICA 2020. [DOI: 10.1655/0018-0831-76.2.178] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Louise A. Rollins-Smith
- Departments of Pathology, Microbiology and Immunology and Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
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13
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Cortázar-Chinarro M, Meyer-Lucht Y, Van der Valk T, Richter-Boix A, Laurila A, Höglund J. Antimicrobial peptide and sequence variation along a latitudinal gradient in two anurans. BMC Genet 2020; 21:38. [PMID: 32228443 PMCID: PMC7106915 DOI: 10.1186/s12863-020-00839-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 03/06/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND While there is evidence of both purifying and balancing selection in immune defense genes, large-scale genetic diversity in antimicrobial peptides (AMPs), an important part of the innate immune system released from dermal glands in the skin, has remained uninvestigated. Here we describe genetic diversity at three AMP loci (Temporin, Brevinin and Palustrin) in two ranid frogs (Rana arvalis and R. temporaria) along a 2000 km latitudinal gradient. We amplified and sequenced part of the Acidic Propiece domain and the hypervariable Mature Peptide domain (~ 150-200 bp) in the three genes using Illumina Miseq and expected to find decreased AMP genetic variation towards the northern distribution limit of the species similarly to studies on MHC genetic patterns. RESULTS We found multiple loci for each AMP and relatively high gene diversity, but no clear pattern of geographic genetic structure along the latitudinal gradient. We found evidence of trans-specific polymorphism in the two species, indicating a common evolutionary origin of the alleles. Temporin and Brevinin did not form monophyletic clades suggesting that they belong to the same gene family. By implementing codon evolution models we found evidence of strong positive selection acting on the Mature Peptide. We also found evidence of diversifying selection as indicated by divergent allele frequencies among populations and high Theta k values. CONCLUSION Our results suggest that AMPs are an important source of adaptive diversity, minimizing the chance of microorganisms developing resistance to individual peptides.
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Affiliation(s)
- Maria Cortázar-Chinarro
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden.
| | - Yvonne Meyer-Lucht
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden.,Centre for Paleogenetics Svante Arrhenius väg 20C, SE-106 91, Stockholm, Sweden
| | - Tom Van der Valk
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden
| | - Alex Richter-Boix
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden
| | - Anssi Laurila
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden
| | - Jacob Höglund
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden
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14
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Bradley PW, Snyder PW, Blaustein AR. Host age alters amphibian susceptibility to Batrachochytrium dendrobatidis, an emerging infectious fungal pathogen. PLoS One 2019; 14:e0222181. [PMID: 31491016 PMCID: PMC6730893 DOI: 10.1371/journal.pone.0222181] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 08/23/2019] [Indexed: 11/18/2022] Open
Abstract
Parasites and pathogens are often aggregated in a minority of susceptible hosts within a population, with a majority of individuals harboring low infection intensities. However, determining the relative importance of host traits to explain this heterogeneity is a challenge. One ecologically important pathogen is Batrachochytrium dendrobatidis (Bd), which causes the disease chytridiomycosis and has been associated with many amphibian population declines worldwide. For many hosts, post-metamorphic stages are generally more susceptible than the larval stage. Yet, examination of the effects of Bd infection at different ages within a life stage, has received little attention. This study investigated the hypothesis that recently-post-metamorphic frogs were more sensitive to chytridiomycosis than older frogs, and that sensitivity to Bd infection decreased as frogs aged. We examined this relationship with Pacific treefrogs (Pseudacris regilla) and red legged frogs (Rana aurora). Age had a strong effect on susceptibility to infection, infection intensity, and survival-but not in the directions we had predicted. In both host species, an increase in age was associated with frogs becoming more susceptible to Bd infection, harboring larger infection intensities, and greater risk of mortality. This suggests that the timing of Bd exposure may influence amphibian population dynamics.
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Affiliation(s)
- Paul W. Bradley
- Environmental Sciences Graduate Program, Oregon State University, Corvallis, Oregon, United States of America
- * E-mail:
| | - Paul W. Snyder
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
| | - Andrew R. Blaustein
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
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15
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Fu M, Waldman B. Ancestral chytrid pathogen remains hypervirulent following its long coevolution with amphibian hosts. Proc Biol Sci 2019; 286:20190833. [PMID: 31161901 DOI: 10.1098/rspb.2019.0833] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Many amphibian species around the world, except in Asia, suffer morbidity and mortality when infected by the emerging infectious pathogen Batrachochytrium dendrobatidis (Bd). A lineage of the amphibian chytrid fungus isolated from South Korean amphibians (BdAsia-1) is evolutionarily basal to recombinant global pandemic lineages (BdGPL) associated with worldwide amphibian population declines. In Asia, the Bd pathogen and its amphibian hosts have coevolved over 100 years or more. Thus, resilience of Asian amphibian populations to infection might result from attenuated virulence of endemic Bd lineages, evolved immunity to the pathogen or both. We compared susceptibilities of an Australasian amphibian, Litoria caerulea, known to lack resistance to BdGPL, with those of three Korean species, Bufo gargarizans, Bombina orientalis and Hyla japonica, after inoculation with BdAsia-1, BdGPL or a blank solution. Subjects became infected in all experimental treatments but Korean species rapidly cleared themselves of infection, regardless of Bd lineage. They survived with no apparent secondary effects. By contrast, L. caerulea, after infection by either BdAsia-1 or BdGPL, suffered deteriorating body condition and carried progressively higher Bd loads over time. Subsequently, most subjects died. Comparing their effects on L. caerulea, BdAsia-1 induced more rapid disease progression than BdGPL. The results suggest that genomic recombination with other lineages was not necessary for the ancestral Bd lineage to evolve hypervirulence over its long period of coevolution with amphibian hosts. The pathogen's virulence may have driven strong selection for immune responses in endemic Asian amphibian host species.
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Affiliation(s)
- Minjie Fu
- 1 Laboratory of Behavioral and Population Ecology, School of Biological Sciences, Seoul National University , Seoul 08826 , South Korea
| | - Bruce Waldman
- 1 Laboratory of Behavioral and Population Ecology, School of Biological Sciences, Seoul National University , Seoul 08826 , South Korea.,2 Department of Integrative Biology, Oklahoma State University , Stillwater, OK 74078 , USA
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16
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Robak MJ, Reinert LK, Rollins-Smith LA, Richards-Zawacki CL. Out in the cold and sick: Low temperatures and fungal infections impair a frog's skin defenses. J Exp Biol 2019; 222:jeb.209445. [DOI: 10.1242/jeb.209445] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Accepted: 09/02/2019] [Indexed: 12/29/2022]
Abstract
Amphibians worldwide continue to battle an emerging infectious disease, chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd). Southern leopard frogs, Rana sphenocephala, are known to become infected with this pathogen, yet they are considered ‘of least concern’ for declines due to chytridiomycosis. Previous studies have shown that R. sphenocephala secretes four antimicrobial peptides (AMPs) onto their skin which may play an important role in limiting susceptibility to chytridiomycosis. Here we examined the (1) effects of temperature and AMP depletion on infections with Bd and (2) effects of temperature and Bd infection on the capacity to secrete AMPs in juvenile leopard frogs. Pathogen burden and mortality were greater in frogs exposed to Bd at low temperature but did not increase following monthly AMP depletion. Both low temperature and Bd exposure reduced the capacity of juvenile frogs to restore peptides after monthly depletions. Frogs held at 14°C were poorly able to restore peptides in comparison with those at 26 °C. Frogs held at 26 °C were better able to restore their peptides, but when exposed to Bd, this capacity was significantly reduced. These results strongly support the hypothesis that both colder temperatures and Bd infections impair the capacity of juvenile frogs to produce and secrete AMPs, an important component of their innate defense against chytrid fungi and other pathogens. Thus, in the face of unpredictable climate changes and enzootic pathogens, assessments of disease risk should consider the potential for effects of environmental variation and pathogen exposure on the quality of host defenses.
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Affiliation(s)
- Matthew J. Robak
- Department of Ecology & Evolutionary Biology, Tulane University, New Orleans, LA 70118, USA
| | - Laura K. Reinert
- Department of Pathology, Microbiology and Immunology Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Louise A. Rollins-Smith
- Department of Pathology, Microbiology and Immunology Vanderbilt University School of Medicine, Nashville, TN 37232, USA
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Corinne L. Richards-Zawacki
- Department of Ecology & Evolutionary Biology, Tulane University, New Orleans, LA 70118, USA
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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17
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Liu J, Chen Z, Chen G, Wang B, Jiang J. Skin innate immunity of diskless-fingered odorous frogs (Odorrana grahami) with spatial-temporal variations. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 89:23-30. [PMID: 30092315 DOI: 10.1016/j.dci.2018.08.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 08/05/2018] [Accepted: 08/05/2018] [Indexed: 06/08/2023]
Abstract
The skin innate immunities of diskless-fingered odorous frogs (Odorrana grahami) from three populations were investigated. The antimicrobial capacities of skin secretions against the 60 representative environmental bacterial strains were evaluated using the values of the minimum inhibitory concentration (MIC) equivalents, which were defined as the volumes of antimicrobial solution just inhibiting the tested bacteria per 1 cm2 of surface area, from 0.06 to 9.10 mL/cm2. Our results revealed significantly different skin antimicrobial capacities among the three populations: Mianning < Huili < Kunming. Within the frog population, the skin antimicrobial capacities are highly variable depending on the season: in Mianning frogs, summer < autumn and spring; in Huili frogs, spring < autumn < summer; in Kunming frogs, autumn < spring < summer. The animal density and body mass significantly impacted the skin antimicrobial capacity, while the sex ratio and soil or water bacterial counts did not.
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Affiliation(s)
- Jiongyu Liu
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, China.
| | - Zhenyong Chen
- College of Life Science, China West Normal University, Nanchong 637009, China
| | - Guiying Chen
- Department of Biology, Sichuan Normal University, Chengdu 610101, China
| | - Bin Wang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, China
| | - Jianping Jiang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, China.
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18
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Grogan LF, Robert J, Berger L, Skerratt LF, Scheele BC, Castley JG, Newell DA, McCallum HI. Review of the Amphibian Immune Response to Chytridiomycosis, and Future Directions. Front Immunol 2018; 9:2536. [PMID: 30473694 PMCID: PMC6237969 DOI: 10.3389/fimmu.2018.02536] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 10/15/2018] [Indexed: 12/27/2022] Open
Abstract
The fungal skin disease, chytridiomycosis (caused by Batrachochytrium dendrobatidis and B. salamandrivorans), has caused amphibian declines and extinctions globally since its emergence. Characterizing the host immune response to chytridiomycosis has been a focus of study with the aim of disease mitigation. However, many aspects of the innate and adaptive arms of this response are still poorly understood, likely due to the wide range of species' responses to infection. In this paper we provide an overview of expected immunological responses (with inference based on amphibian and mammalian immunology), together with a synthesis of current knowledge about these responses for the amphibian-chytridiomycosis system. We structure our review around four key immune stages: (1) the naïve immunocompetent state, (2) immune defenses that are always present (constitutive defenses), (3) mechanisms for recognition of a pathogen threat and innate immune defenses, and (4) adaptive immune responses. We also evaluate the current hot topics of immunosuppression and immunopathology in chytridiomycosis, and discuss their respective roles in pathogenesis. Our synthesis reveals that susceptibility to chytridiomycosis is likely to be multifactorial. Susceptible amphibians appear to have ineffective constitutive and innate defenses, and a late-stage response characterized by immunopathology and Bd-induced suppression of lymphocyte responses. Overall, we identify substantial gaps in current knowledge, particularly concerning the entire innate immune response (mechanisms of initial pathogen detection and possible immunoevasion by Bd, degree of activation and efficacy of the innate immune response, the unexpected absence of innate leukocyte infiltration, and the cause and role of late-stage immunopathology in pathogenesis). There are also gaps concerning most of the adaptive immune system (the relative importance of B and T cell responses for pathogen clearance, the capacity and extent of immunological memory, and specific mechanisms of pathogen-induced immunosuppression). Improving our capacity for amphibian immunological research will require selection of an appropriate Bd-susceptible model species, the development of taxon-specific affinity reagents and cell lines for functional assays, and the application of a suite of conventional and emerging immunological methods. Despite current knowledge gaps, immunological research remains a promising avenue for amphibian conservation management.
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Affiliation(s)
- Laura F Grogan
- Environmental Futures Research Institute and School of Environment and Science, Griffith University, Nathan, QLD, Australia
| | - Jacques Robert
- University of Rochester Medical Center, Rochester, NY, United States
| | - Lee Berger
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia.,Faculty of Veterinary and Agricultural Sciences, Melbourne Veterinary School, University of Melbourne, Werribee, VIC, Australia
| | - Lee F Skerratt
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia.,Faculty of Veterinary and Agricultural Sciences, Melbourne Veterinary School, University of Melbourne, Werribee, VIC, Australia
| | - Benjamin C Scheele
- Fenner School of Environment and Society, The Australian National University, Canberra, ACT, Australia.,Threatened Species Recovery Hub, National Environmental Science Program, Fenner School of Environment and Society, The Australian National University, Canberra, ACT, Australia
| | - J Guy Castley
- Environmental Futures Research Institute and School of Environment and Science, Griffith University, Nathan, QLD, Australia
| | - David A Newell
- Forest Research Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, NSW, Australia
| | - Hamish I McCallum
- Environmental Futures Research Institute and School of Environment and Science, Griffith University, Nathan, QLD, Australia
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19
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Griffiths SM, Harrison XA, Weldon C, Wood MD, Pretorius A, Hopkins K, Fox G, Preziosi RF, Antwis RE. Genetic variability and ontogeny predict microbiome structure in a disease-challenged montane amphibian. THE ISME JOURNAL 2018; 12:2506-2517. [PMID: 29942072 PMCID: PMC6155040 DOI: 10.1038/s41396-018-0167-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Revised: 02/09/2018] [Accepted: 03/10/2018] [Indexed: 12/21/2022]
Abstract
Amphibian populations worldwide are at risk of extinction from infectious diseases, including chytridiomycosis caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd). Amphibian cutaneous microbiomes interact with Bd and can confer protective benefits to the host. The composition of the microbiome itself is influenced by many environment- and host-related factors. However, little is known about the interacting effects of host population structure, genetic variation and developmental stage on microbiome composition and Bd prevalence across multiple sites. Here we explore these questions in Amietia hymenopus, a disease-affected frog in southern Africa. We use microsatellite genotyping and 16S amplicon sequencing to show that the microbiome associated with tadpole mouthparts is structured spatially, and is influenced by host genotype and developmental stage. We observed strong genetic structure in host populations based on rivers and geographic distances, but this did not correspond to spatial patterns in microbiome composition. These results indicate that demographic and host genetic factors affect microbiome composition within sites, but different factors are responsible for host population structure and microbiome structure at the between-site level. Our results help to elucidate complex within- and among- population drivers of microbiome structure in amphibian populations. That there is a genetic basis to microbiome composition in amphibians could help to inform amphibian conservation efforts against infectious diseases.
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Affiliation(s)
- Sarah M Griffiths
- School of Science and the Environment, Manchester Metropolitan University, Manchester, UK.
| | | | - Ché Weldon
- Unit for Environmental Research and Management, Faculty of Natural Science, North-West University, Potchefstroom, South Africa
| | - Michael D Wood
- School of Environment and Life Sciences, University of Salford, Salford, UK
| | - Abigail Pretorius
- Unit for Environmental Research and Management, Faculty of Natural Science, North-West University, Potchefstroom, South Africa
| | - Kevin Hopkins
- Institute of Zoology, Zoological Society of London, London, UK
| | - Graeme Fox
- School of Science and the Environment, Manchester Metropolitan University, Manchester, UK
| | - Richard F Preziosi
- School of Science and the Environment, Manchester Metropolitan University, Manchester, UK
| | - Rachael E Antwis
- Unit for Environmental Research and Management, Faculty of Natural Science, North-West University, Potchefstroom, South Africa.
- School of Environment and Life Sciences, University of Salford, Salford, UK.
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20
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Flechas SV, Acosta-González A, Escobar LA, Kueneman JG, Sánchez-Quitian ZA, Parra-Giraldo CM, Rollins-Smith LA, Reinert LK, Vredenburg VT, Amézquita A, Woodhams DC. Microbiota and skin defense peptides may facilitate coexistence of two sympatric Andean frog species with a lethal pathogen. ISME JOURNAL 2018; 13:361-373. [PMID: 30254321 DOI: 10.1038/s41396-018-0284-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 08/21/2018] [Accepted: 08/23/2018] [Indexed: 12/13/2022]
Abstract
Management of hyper-virulent generalist pathogens is an emergent global challenge, yet for most disease systems we lack a basic understanding as to why some host species suffer mass mortalities, while others resist epizootics. We studied two sympatric species of frogs from the Colombian Andes, which coexist with the amphibian pathogen Batrachochytrium dendrobatidis (Bd), to understand why some species did not succumb to the infection. We found high Bd prevalence in juveniles for both species, yet infection intensities remained low. We also found that bacterial community composition and host defense peptides are specific to amphibian life stages. We detected abundant Bd-inhibitory skin bacteria across life stages and Bd-inhibitory defense peptides post-metamorphosis in both species. Bd-inhibitory bacteria were proportionally more abundant in adults of both species than in earlier developmental stages. We tested for activity of peptides against the skin microbiota and found that in general peptides did not negatively affect bacterial growth and in some instances facilitated growth. Our results suggest that symbiotic bacteria and antimicrobial peptides may be co-selected for, and that together they contribute to the ability of Andean amphibian species to coexist with the global pandemic lineage of Bd.
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Affiliation(s)
- Sandra V Flechas
- Department of Biological Sciences, Universidad de los Andes, Bogotá, 111711, Colombia. .,Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, Bogotá, Colombia.
| | | | - Laura A Escobar
- Department of Microbiology, Faculty of Sciences, Pontificia Universidad Javeriana, Bogotá, AA 56710, Colombia
| | - Jordan G Kueneman
- Biology Department, University of Massachusetts Boston, Boston, MA, 02125, USA.,Smithsonian Tropical Research Institute, Panama, Apartado 0843-03092, Republic of Panama
| | - Zilpa Adriana Sánchez-Quitian
- Department of Microbiology, Faculty of Sciences, Pontificia Universidad Javeriana, Bogotá, AA 56710, Colombia.,Environmental Management Group, Department of Biology and Microbiology, Universidad de Boyacá, Tunja, 150000003, Colombia
| | - Claudia M Parra-Giraldo
- Department of Microbiology, Faculty of Sciences, Pontificia Universidad Javeriana, Bogotá, AA 56710, Colombia
| | - Louise A Rollins-Smith
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, School of Medicine, Nashville, TN, 37232, USA
| | - Laura K Reinert
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, School of Medicine, Nashville, TN, 37232, USA
| | - Vance T Vredenburg
- Department of Biology, San Francisco State University, San Francisco, CA, 94132-1722, USA
| | - Adolfo Amézquita
- Department of Biological Sciences, Universidad de los Andes, Bogotá, 111711, Colombia
| | - Douglas C Woodhams
- Biology Department, University of Massachusetts Boston, Boston, MA, 02125, USA.,Smithsonian Tropical Research Institute, Panama, Apartado 0843-03092, Republic of Panama
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21
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Pereira KE, Crother BI, Sever DM, Fontenot CL, Pojman JA, Wilburn DB, Woodley SK. Skin glands of an aquatic salamander vary in size and distribution and release antimicrobial secretions effective against chytrid fungal pathogens. ACTA ACUST UNITED AC 2018; 221:jeb.183707. [PMID: 29880633 DOI: 10.1242/jeb.183707] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 05/31/2018] [Indexed: 12/29/2022]
Abstract
Amphibian skin is unique among vertebrate classes, containing a large number of multicellular exocrine glands that vary among species and have diverse functions. The secretions of skin glands contain a rich array of bioactive compounds including antimicrobial peptides (AMPs). Such compounds are important for amphibian innate immune responses and may protect some species from chytridiomycosis, a lethal skin disease caused by the fungal pathogens Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal). While the bioactivity of skin secretions against Bd has been assessed for many amphibian taxa, similar studies are lacking for Bsal, a chytrid fungus that is especially pathogenic for salamanders. We studied the skin glands and their potential functions in an aquatic salamander, the three-toed amphiuma (Amphiuma tridactylum). Skin secretions of captive adult salamanders were analyzed by RP-HPLC and tested against the growth of Bd and Bsal using in vitro assays. We found that compounds within collected skin secretions were similar between male and female salamanders and inhibited the growth of Bd and Bsal. Thus, skin secretions that protect against Bd may also provide protection against Bsal. Histological examination of the skin glands of preserved salamanders revealed the presence of enlarged granular glands concentrated within caudal body regions. A site of potential gland specialization was identified at the tail base and may indicate specialized granular glands related to courtship and communication.
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Affiliation(s)
- Kenzie E Pereira
- Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15282, USA .,Department of Biology, Southeastern Louisiana University, Hammond, LA 70402, USA
| | - Brian I Crother
- Department of Biology, Southeastern Louisiana University, Hammond, LA 70402, USA
| | - David M Sever
- Department of Biology, Southeastern Louisiana University, Hammond, LA 70402, USA
| | - Clifford L Fontenot
- Department of Biology, Southeastern Louisiana University, Hammond, LA 70402, USA
| | - John A Pojman
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Damien B Wilburn
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Sarah K Woodley
- Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15282, USA
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22
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Brannelly LA, Roberts AA, Skerratt LF, Berger L. Using Terminal Transferase-mediated dUTP Nick End-labelling (TUNEL) and Caspase 3/7 Assays to Measure Epidermal Cell Death in Frogs with Chytridiomycosis. J Vis Exp 2018. [PMID: 29863673 DOI: 10.3791/57345] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Amphibians are experiencing a great loss in biodiversity globally and one of the major causes is the infectious disease chytridiomycosis. This disease is caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), which infects and disrupts frog epidermis; however, pathological changes have not been explicitly characterized. Apoptosis (programmed cell death) can be used by pathogens to damage host tissue, but can also be a host mechanism of disease resistance for pathogen removal. In this study, we quantify epidermal cell death of infected and uninfected animals using two different assays: terminal transferase-mediated dUTP nick end-labelling (TUNEL), and caspase 3/7. Using ventral, dorsal, and thigh skin tissue in the TUNEL assay, we observe cell death in the epidermal cells in situ of clinically infected animals and compare cell death with uninfected animals using fluorescent microscopy. In order to determine how apoptosis levels in the epidermis change over the course of infection we remove toe-tip samples fortnightly over an 8-week period, and use a caspase 3/7 assay with extracted proteins to quantify activity within the samples. We then correlate caspase 3/7 activity with infection load. The TUNEL assay is useful for localization of cell death in situ, but is expensive and time intensive per sample. The caspase 3/7 assay is efficient for large sample sizes and time course experiments. However, because frog toe tip biopsies are small there is limited extract available for sample standardization via protein quantification methods, such as the Bradford assay. Therefore, we suggest estimating skin surface area through photographic analysis of toe biopsies to avoid consuming extracts during sample standardization.
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Affiliation(s)
- Laura A Brannelly
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University; Department of Biological Sciences, University of Pittsburgh;
| | - Alexandra A Roberts
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University
| | - Lee F Skerratt
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University
| | - Lee Berger
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University
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23
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Johnson PTJ, Calhoun DM, Stokes AN, Susbilla CB, McDevitt-Galles T, Briggs CJ, Hoverman JT, Tkach VV, de Roode JC. Of poisons and parasites-the defensive role of tetrodotoxin against infections in newts. J Anim Ecol 2018; 87:1192-1204. [PMID: 29476541 DOI: 10.1111/1365-2656.12816] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 01/17/2018] [Indexed: 11/29/2022]
Abstract
Classical research on animal toxicity has focused on the role of toxins in protection against predators, but recent studies suggest these same compounds can offer a powerful defense against parasites and infectious diseases. Newts in the genus Taricha are brightly coloured and contain the potent neurotoxin, tetrodotoxin (TTX), which is hypothesized to have evolved as a defense against vertebrate predators such as garter snakes. However, newt populations often vary dramatically in toxicity, which is only partially explained by predation pressure. The primary aim of this study was to evaluate the relationships between TTX concentration and infection by parasites. By systematically assessing micro- and macroparasite infections among 345 adult newts (sympatric populations of Taricha granulosa and T. torosa), we detected 18 unique taxa of helminths, fungi, viruses and protozoans. For both newt species, per-host concentrations of TTX, which varied from undetectable to >60 μg/cm2 skin, negatively predicted overall parasite richness as well as the likelihood of infection by the chytrid fungus, Batrachochytrium dendrobatidis, and ranavirus. No such effect was found on infection load among infected hosts. Despite commonly occurring at the same wetlands, T. torosa supported higher parasite richness and average infection load than T. granulosa. Host body size and sex (females > males) tended to positively predict infection levels in both species. For hosts in which we quantified leucocyte profiles, total white blood cell count correlated positively with both parasite richness and total infection load. By coupling data on host toxicity and infection by a broad range of micro- and macroparasites, these results suggest that-alongside its effects on predators-tetrodotoxin may help protect newts against parasitic infections, highlighting the importance of integrative research on animal chemistry, immunological defenses and natural enemy ecology.
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Affiliation(s)
- Pieter T J Johnson
- Department of Ecology and Evolutionary Biology, University of Colorado at Boulder, Boulder, CO, USA
| | - Dana M Calhoun
- Department of Ecology and Evolutionary Biology, University of Colorado at Boulder, Boulder, CO, USA
| | - Amber N Stokes
- Department of Biology, California State University, Bakersfield, CA, USA
| | - Calvin B Susbilla
- Department of Biology, California State University, Bakersfield, CA, USA
| | - Travis McDevitt-Galles
- Department of Ecology and Evolutionary Biology, University of Colorado at Boulder, Boulder, CO, USA
| | - Cheryl J Briggs
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA, USA
| | - Jason T Hoverman
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, USA
| | - Vasyl V Tkach
- Department of Biology, University of North Dakota, Grand Forks, ND, USA
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24
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Bower DS, Mengersen K, Alford RA, Schwarzkopf L. Using a Bayesian network to clarify areas requiring research in a host-pathogen system. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2017; 31:1373-1382. [PMID: 28464282 DOI: 10.1111/cobi.12950] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 03/24/2017] [Accepted: 04/17/2017] [Indexed: 06/07/2023]
Abstract
Bayesian network analyses can be used to interactively change the strength of effect of variables in a model to explore complex relationships in new ways. In doing so, they allow one to identify influential nodes that are not well studied empirically so that future research can be prioritized. We identified relationships in host and pathogen biology to examine disease-driven declines of amphibians associated with amphibian chytrid fungus (Batrachochytrium dendrobatidis). We constructed a Bayesian network consisting of behavioral, genetic, physiological, and environmental variables that influence disease and used them to predict host population trends. We varied the impacts of specific variables in the model to reveal factors with the most influence on host population trend. The behavior of the nodes (the way in which the variables probabilistically responded to changes in states of the parents, which are the nodes or variables that directly influenced them in the graphical model) was consistent with published results. The frog population had a 49% probability of decline when all states were set at their original values, and this probability increased when body temperatures were cold, the immune system was not suppressing infection, and the ambient environment was conducive to growth of B. dendrobatidis. These findings suggest the construction of our model reflected the complex relationships characteristic of host-pathogen interactions. Changes to climatic variables alone did not strongly influence the probability of population decline, which suggests that climate interacts with other factors such as the capacity of the frog immune system to suppress disease. Changes to the adaptive immune system and disease reservoirs had a large effect on the population trend, but there was little empirical information available for model construction. Our model inputs can be used as a base to examine other systems, and our results show that such analyses are useful tools for reviewing existing literature, identifying links poorly supported by evidence, and understanding complexities in emerging infectious-disease systems.
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Affiliation(s)
- D S Bower
- College of Science and Engineering, James Cook University, 1 James Cook Drive, Douglas, QLD, 4811, Australia
| | - K Mengersen
- Faculty of Science and Engineering, Mathematical Sciences, Statistical Science, Queensland University of Technology, Brisbane, QLD, 4000, Australia
| | - R A Alford
- College of Science and Engineering, James Cook University, 1 James Cook Drive, Douglas, QLD, 4811, Australia
| | - L Schwarzkopf
- College of Science and Engineering, James Cook University, 1 James Cook Drive, Douglas, QLD, 4811, Australia
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25
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Greenberg DA, Palen WJ, Mooers AØ. Amphibian species traits, evolutionary history and environment predict Batrachochytrium dendrobatidis infection patterns, but not extinction risk. Evol Appl 2017; 10:1130-1145. [PMID: 29151866 PMCID: PMC5680631 DOI: 10.1111/eva.12520] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 07/18/2017] [Indexed: 12/17/2022] Open
Abstract
The fungal pathogen Batrachochytrium dendrobatidis (B. dendrobatidis) has emerged as a major agent of amphibian extinction, requiring conservation intervention for many susceptible species. Identifying susceptible species is challenging, but many aspects of species biology are predicted to influence the evolution of host resistance, tolerance, or avoidance strategies towards disease. In turn, we may expect species exhibiting these distinct strategies to differ in their ability to survive epizootic disease outbreaks. Here, we test for phylogenetic and trait-based patterns of B. dendrobatidis infection risk and infection intensity among 302 amphibian species by compiling a global data set of B. dendrobatidis infection surveys across 95 sites. We then use best-fit models that associate traits, taxonomy and environment with B. dendrobatidis infection risk and intensity to predict host disease mitigation strategies (tolerance, resistance, avoidance) for 122 Neotropical amphibian species that experienced epizootic B. dendrobatidis outbreaks, and noted species persistence or extinction from these events. Aspects of amphibian species life history, habitat use and climatic niche were consistently linked to variation in B. dendrobatidis infection patterns across sites around the world. However, predicted B. dendrobatidis infection risk and intensity based on site environment and species traits did not reveal a consistent pattern between the predicted host disease mitigation strategy and extinction outcome. This suggests that either tolerant or resistant species may have no advantage in ameliorating disease during epizootic events, or that other factors drive the persistence of amphibian populations during chytridiomycosis outbreaks. These results suggest that using a trait-based approach may allow us to identify species with resistance or tolerance to endemic B. dendrobatidis infections, but that this approach may be insufficient to ultimately identify species at risk of extinction from epizootics.
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Affiliation(s)
- Dan A. Greenberg
- Department of Biological Sciences and Crawford Laboratory of Evolutionary StudiesSimon Fraser UniversityBurnabyBCCanada
- Department of Biological Sciences and Earth to Ocean Research GroupSimon Fraser UniversityBurnabyBCCanada
| | - Wendy J. Palen
- Department of Biological Sciences and Earth to Ocean Research GroupSimon Fraser UniversityBurnabyBCCanada
| | - Arne Ø. Mooers
- Department of Biological Sciences and Crawford Laboratory of Evolutionary StudiesSimon Fraser UniversityBurnabyBCCanada
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Burkart D, Flechas SV, Vredenburg VT, Catenazzi A. Cutaneous bacteria, but not peptides, are associated with chytridiomycosis resistance in Peruvian marsupial frogs. Anim Conserv 2017. [DOI: 10.1111/acv.12352] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- D. Burkart
- Department of Zoology Southern Illinois University Carbondale IL USA
| | - S. V. Flechas
- Department of Biological Sciences Universidad de los Andes Bogotá Colombia
| | - V. T. Vredenburg
- Department of Biology San Francisco State University San Francisco CA USA
| | - A. Catenazzi
- Department of Zoology Southern Illinois University Carbondale IL USA
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27
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Davis LR, Bigler L, Woodhams DC. Developmental trajectories of amphibian microbiota: response to bacterial therapy depends on initial community structure. Environ Microbiol 2017; 19:1502-1517. [DOI: 10.1111/1462-2920.13707] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 02/16/2017] [Accepted: 02/17/2017] [Indexed: 01/21/2023]
Affiliation(s)
- Leyla R. Davis
- Institute of Evolutionary Biology and Environmental Studies
| | - Laurent Bigler
- Institute of Organic Chemistry; University of Zurich; Winterthurerstrasse 190 Zurich CH-8057 Switzerland
| | - Douglas C. Woodhams
- Institute of Evolutionary Biology and Environmental Studies
- Department of Biology; University of Massachusetts Boston; 100 Morrissey Blvd. Boston MA 02125 USA
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28
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Brannelly LA, Roberts AA, Skerratt LF, Berger L. Epidermal cell death in frogs with chytridiomycosis. PeerJ 2017; 5:e2925. [PMID: 28168107 PMCID: PMC5291105 DOI: 10.7717/peerj.2925] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 12/19/2016] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Amphibians are declining at an alarming rate, and one of the major causes of decline is the infectious disease chytridiomycosis. Parasitic fungal sporangia occur within epidermal cells causing epidermal disruption, but these changes have not been well characterised. Apoptosis (planned cell death) can be a damaging response to the host but may alternatively be a mechanism of pathogen removal for some intracellular infections. METHODS In this study we experimentally infected two endangered amphibian species Pseudophryne corroboree and Litoria verreauxii alpina with the causal agent of chytridiomycosis. We quantified cell death in the epidermis through two assays: terminal transferase-mediated dUTP nick end-labelling (TUNEL) and caspase 3/7. RESULTS Cell death was positively associated with infection load and morbidity of clinically infected animals. In infected amphibians, TUNEL positive cells were concentrated in epidermal layers, correlating to the localisation of infection within the skin. Caspase activity was stable and low in early infection, where pathogen loads were light but increasing. In animals that recovered from infection, caspase activity gradually returned to normal as the infection cleared. Whereas, in amphibians that did not recover, caspase activity increased dramatically when infection loads peaked. DISCUSSION Increased cell death may be a pathology of the fungal parasite, likely contributing to loss of skin homeostatic functions, but it is also possible that apoptosis suppression may be used initially by the pathogen to help establish infection. Further research should explore the specific mechanisms of cell death and more specifically apoptosis regulation during fungal infection.
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Affiliation(s)
- Laura A Brannelly
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University , Townsville , QLD , Australia
| | - Alexandra A Roberts
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University , Townsville , QLD , Australia
| | - Lee F Skerratt
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia; Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Lee Berger
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia; Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, Victoria, Australia
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29
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Pathological and phylogenetic characterization ofAmphibiothecumsp. infection in an isolated amphibian (Lissotriton helveticus) population on the island of Rum (Scotland). Parasitology 2016; 144:484-496. [DOI: 10.1017/s0031182016001943] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
SUMMARYOutbreaks of cutaneous infectious disease in amphibians are increasingly being attributed to an overlooked group of fungal-like pathogens, the Dermocystids. During the last 10 years on the Isle of Rum, Scotland, palmate newts (Lissotriton helveticus) have been reportedly afflicted by unusual skin lesions. Here we present pathological and molecular findings confirming that the pathogen associated with these lesions is a novel organism of the order Dermocystida, and represents the first formally reported, and potentially lethal, case of amphibian Dermocystid infection in the UK. Whilst the gross pathology and the parasite cyst morphology were synonymous to those described in a study from infectedL. helveticusin France, we observed a more extreme clinical outcome on Rum involving severe subcutaneous oedema. Phylogenetic topologies supported synonymy between Dermocystid sequences from Rum and France and as well as their distinction fromAmphibiocystidiumspp. Phylogenetic analysis also suggested that the amphibian-infecting Dermocystids are not monophyletic. We conclude that theL. helveticus-infecting pathogen represents a single, novel species;Amphibiothecum meredithae.
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30
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Davis LR, Klonoski K, Rutschow HL, Van Wijk KJ, Sun Q, Haribal MM, Saporito RA, Vega A, Rosenblum EB, Zamudio KR, Robertson JM. Host Defense Skin Peptides Vary with Color Pattern in the Highly Polymorphic Red-Eyed Treefrog. Front Ecol Evol 2016. [DOI: 10.3389/fevo.2016.00097] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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31
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Bókony V, Móricz ÁM, Tóth Z, Gál Z, Kurali A, Mikó Z, Pásztor K, Szederkényi M, Tóth Z, Ujszegi J, Üveges B, Krüzselyi D, Capon RJ, Hoi H, Hettyey A. Variation in Chemical Defense Among Natural Populations of Common Toad, Bufo bufo, Tadpoles: the Role of Environmental Factors. J Chem Ecol 2016; 42:329-38. [PMID: 27059330 DOI: 10.1007/s10886-016-0690-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Revised: 01/20/2016] [Accepted: 03/29/2016] [Indexed: 01/19/2023]
Abstract
Defensive toxins are widespread in nature, yet we know little about how various environmental factors shape the evolution of chemical defense, especially in vertebrates. In this study we investigated the natural variation in the amount and composition of bufadienolide toxins, and the relative importance of ecological factors in predicting that variation, in larvae of the common toad, Bufo bufo, an amphibian that produces toxins de novo. We found that tadpoles' toxin content varied markedly among populations, and the number of compounds per tadpole also differed between two geographical regions. The most consistent predictor of toxicity was the strength of competition, indicating that tadpoles produced more compounds and larger amounts of toxins when coexisting with more competitors. Additionally, tadpoles tended to contain larger concentrations of bufadienolides in ponds that were less prone to desiccation, suggesting that the costs of toxin production can only be afforded by tadpoles that do not need to drastically speed up their development. Interestingly, this trade-off was not alleviated by higher food abundance, as periphyton biomass had negligible effect on chemical defense. Even more surprisingly, we found no evidence that higher predation risk enhances chemical defenses, suggesting that low predictability of predation risk and high mortality cost of low toxicity might select for constitutive expression of chemical defense irrespective of the actual level of predation risk. Our findings highlight that the variation in chemical defense may be influenced by environmental heterogeneity in both the need for, and constraints on, toxicity as predicted by optimal defense theory.
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Affiliation(s)
- Veronika Bókony
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó u. 15, H-1022, Budapest, Hungary.
| | - Ágnes M Móricz
- Department of Pathophysiology, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó u. 15, H-1022, Budapest, Hungary
| | - Zsófia Tóth
- Department of Evolutionary Zoology and Human Biology, University of Debrecen, Egyetem tér 1, H-4032, Debrecen, Hungary
| | - Zoltán Gál
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó u. 15, H-1022, Budapest, Hungary.,Agricultural Biotechnology Institute, NARIC, Szentgyörgyi Albert u. 4, H-2100, Gödöllő, Hungary
| | - Anikó Kurali
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó u. 15, H-1022, Budapest, Hungary
| | - Zsanett Mikó
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó u. 15, H-1022, Budapest, Hungary
| | - Katalin Pásztor
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó u. 15, H-1022, Budapest, Hungary
| | - Márk Szederkényi
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó u. 15, H-1022, Budapest, Hungary.,Department of Integrative Biology and Evolution, Konrad Lorenz Institute of Ethology, University of Veterinary Medicine, Savoyenstrasse 1, 1160, Vienna, Austria
| | - Zoltán Tóth
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó u. 15, H-1022, Budapest, Hungary
| | - János Ujszegi
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó u. 15, H-1022, Budapest, Hungary
| | - Bálint Üveges
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó u. 15, H-1022, Budapest, Hungary.,Department of Integrative Biology and Evolution, Konrad Lorenz Institute of Ethology, University of Veterinary Medicine, Savoyenstrasse 1, 1160, Vienna, Austria
| | - Dániel Krüzselyi
- Department of Pathophysiology, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó u. 15, H-1022, Budapest, Hungary
| | - Robert J Capon
- Institute for Molecular Bioscience, University of Queensland, St Lucia, QLD, 4072, Australia
| | - Herbert Hoi
- Department of Integrative Biology and Evolution, Konrad Lorenz Institute of Ethology, University of Veterinary Medicine, Savoyenstrasse 1, 1160, Vienna, Austria
| | - Attila Hettyey
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó u. 15, H-1022, Budapest, Hungary
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Woodhams DC, Bell SC, Bigler L, Caprioli RM, Chaurand P, Lam BA, Reinert LK, Stalder U, Vazquez VM, Schliep K, Hertz A, Rollins-Smith LA. Life history linked to immune investment in developing amphibians. CONSERVATION PHYSIOLOGY 2016; 4:cow025. [PMID: 27928507 PMCID: PMC5001151 DOI: 10.1093/conphys/cow025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 05/09/2016] [Accepted: 05/14/2016] [Indexed: 05/03/2023]
Abstract
The broad diversity of amphibian developmental strategies has been shaped, in part, by pathogen pressure, yet trade-offs between the rate of larval development and immune investment remain poorly understood. The expression of antimicrobial peptides (AMPs) in skin secretions is a crucial defense against emerging amphibian pathogens and can also indirectly affect host defense by influencing the composition of skin microbiota. We examined the constitutive or induced expression of AMPs in 17 species at multiple life-history stages. We found that AMP defenses in tadpoles of species with short larval periods (fast pace of life) were reduced in comparison with species that overwinter as tadpoles and grow to a large size. A complete set of defensive peptides emerged soon after metamorphosis. These findings support the hypothesis that species with a slow pace of life invest energy in AMP production to resist potential pathogens encountered during the long larval period, whereas species with a fast pace of life trade this investment in defense for more rapid growth and development.
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Affiliation(s)
- Douglas C Woodhams
- Department of Biology, University of Massachusetts Boston, 100 Morrissey Blvd., Boston, MA 02125, USA
- Corresponding author: Department of Biology, University of Massachusetts Boston, 100 Morrissey Blvd., Boston, MA 02125, USA. Tel: +1 617 287 6679.
| | - Sara C Bell
- College of Marine and Environmental Sciences, James Cook University, Townsville, QLD 4811, Australia
| | - Laurent Bigler
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Richard M Caprioli
- Mass Spectrometry Research Center and Department of Biochemistry, Vanderbilt University, Nashville, TN 37232-8575, USA
| | - Pierre Chaurand
- Department of Chemistry, Université de Montréal, Montreal, QC, Canada H3T 1J4
| | - Brianna A Lam
- Department of Biology, James Madison University, MSC 7801, Harrisonburg, VA 22807, USA
| | - Laura K Reinert
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232-2363, USA
| | - Urs Stalder
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | | | - Klaus Schliep
- Department of Biology, University of Massachusetts Boston, 100 Morrissey Blvd., Boston, MA 02125, USA
| | - Andreas Hertz
- Department of Biology, University of Massachusetts Boston, 100 Morrissey Blvd., Boston, MA 02125, USA
| | - Louise A Rollins-Smith
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232-2363, USA
- Department of Biological Science, Vanderbilt University, Nashville, TN 37235-1634, USA
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232-2363, USA
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33
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Bradley PW, Gervasi SS, Hua J, Cothran RD, Relyea RA, Olson DH, Blaustein AR. Differences in sensitivity to the fungal pathogen Batrachochytrium dendrobatidis among amphibian populations. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2015; 29:1347-1356. [PMID: 26219571 DOI: 10.1111/cobi.12566] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Revised: 01/27/2015] [Accepted: 02/22/2015] [Indexed: 05/22/2023]
Abstract
Contributing to the worldwide biodiversity crisis are emerging infectious diseases, which can lead to extirpations and extinctions of hosts. For example, the infectious fungal pathogen Batrachochytrium dendrobatidis (Bd) is associated with worldwide amphibian population declines and extinctions. Sensitivity to Bd varies with species, season, and life stage. However, there is little information on whether sensitivity to Bd differs among populations, which is essential for understanding Bd-infection dynamics and for formulating conservation strategies. We experimentally investigated intraspecific differences in host sensitivity to Bd across 10 populations of wood frogs (Lithobates sylvaticus) raised from eggs to metamorphosis. We exposed the post-metamorphic wood frogs to Bd and monitored survival for 30 days under controlled laboratory conditions. Populations differed in overall survival and mortality rate. Infection load also differed among populations but was not correlated with population differences in risk of mortality. Such population-level variation in sensitivity to Bd may result in reservoir populations that may be a source for the transmission of Bd to other sensitive populations or species. Alternatively, remnant populations that are less sensitive to Bd could serve as sources for recolonization after epidemic events.
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Affiliation(s)
- Paul W Bradley
- Environmental Sciences Graduate Program, Oregon State University, 104 Wilkinson Hall, Corvallis, OR, 97331, U.S.A
| | - Stephanie S Gervasi
- Department of Integrative Biology, University of South Florida, 4202 E Fowler Avenue, Tampa, FL, 33620, U.S.A
| | - Jessica Hua
- Department of Forestry and Natural Resources, Purdue University, 715 West State Street, West Lafayette, IN, 47907, U.S.A
| | - Rickey D Cothran
- Department of Biological Sciences, Southwestern Oklahoma University, 100 Campus Drive, Weatherford, OK, 73096, U.S.A
| | - Rick A Relyea
- Department of Biological Sciences, BT2115, Rensselaer Polytechnic Institute, Troy, NY, 12180, U.S.A
| | - Deanna H Olson
- USDA Forest Service, Pacific Northwest Research Station, 3200 SW Jefferson Way, Corvallis, OR, 97331, U.S.A
| | - Andrew R Blaustein
- Environmental Sciences Graduate Program, Oregon State University, 104 Wilkinson Hall, Corvallis, OR, 97331, U.S.A
- Department of Integrative Biology, Oregon State University, 3029 Cordley Hall, Corvallis, OR, 97331, U.S.A
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34
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Sapsford SJ, Voordouw MJ, Alford RA, Schwarzkopf L. Infection dynamics in frog populations with different histories of decline caused by a deadly disease. Oecologia 2015; 179:1099-110. [PMID: 26293680 DOI: 10.1007/s00442-015-3422-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 08/07/2015] [Indexed: 10/23/2022]
Abstract
Pathogens can drive host population dynamics. Chytridiomycosis is a fungal disease of amphibians that is caused by the fungus Batrachochytrium dendrobatidis (Bd). This pathogen has caused declines and extinctions in some host species whereas other host species coexist with Bd without suffering declines. In the early 1990s, Bd extirpated populations of the endangered common mistfrog, Litoria rheocola, at high-elevation sites, while populations of the species persisted at low-elevation sites. Today, populations have reappeared at many high-elevation sites where they presently co-exist with the fungus. We conducted a capture-mark-recapture (CMR) study of six populations of L. rheocola over 1 year, at high and low elevations. We used multistate CMR models to determine which factors (Bd infection status, site type, and season) influenced rates of frog survival, recapture, infection, and recovery from infection. We observed Bd-induced mortality of individual frogs, but did not find any significant effect of Bd infection on the survival rate of L. rheocola at the population level. Survival and recapture rates depended on site type and season. Infection rate was highest in winter when temperatures were favourable for pathogen growth, and differed among site types. The recovery rate was high (75.7-85.8%) across seasons, and did not differ among site types. The coexistence of L. rheocola with Bd suggests that (1) frog populations are becoming resistant to the fungus, (2) Bd may have evolved lower virulence, or (3) current environmental conditions may be inhibiting outbreaks of the fatal disease.
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Affiliation(s)
- Sarah J Sapsford
- School of Marine and Tropical Biology, James Cook University, Townsville, Australia. .,School of Veterinary and Life Sciences, Murdoch University, Perth, Australia.
| | | | - Ross A Alford
- School of Marine and Tropical Biology, James Cook University, Townsville, Australia
| | - Lin Schwarzkopf
- School of Marine and Tropical Biology, James Cook University, Townsville, Australia
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35
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Heard GW, Thomas CD, Hodgson JA, Scroggie MP, Ramsey DSL, Clemann N. Refugia and connectivity sustain amphibian metapopulations afflicted by disease. Ecol Lett 2015; 18:853-863. [PMID: 26108261 DOI: 10.1111/ele.12463] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 04/28/2015] [Accepted: 05/28/2015] [Indexed: 01/13/2023]
Abstract
Metapopulation persistence in fragmented landscapes depends on habitat patches that can support resilient local populations and sufficient connectivity between patches. Yet epidemiological theory for metapopulations has largely overlooked the capacity of particular patches to act as refuges from disease, and has suggested that connectivity can undermine persistence. Here, we show that relatively warm and saline wetlands are environmental refuges from chytridiomycosis for an endangered Australian frog, and act jointly with connectivity to sustain frog metapopulations. We coupled models of microclimate and infection probability to map chytrid prevalence, and demonstrate a strong negative relationship between chytrid prevalence and the persistence of frog populations. Simulations confirm that frog metapopulations are likely to go extinct when they lack environmental refuges from disease and lose connectivity between patches. This study demonstrates that environmental heterogeneity can mediate host-pathogen interactions in fragmented landscapes, and provides evidence that connectivity principally supports host metapopulations afflicted by facultative pathogens.
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Affiliation(s)
- Geoffrey W Heard
- School of BioSciences, University of Melbourne, Parkville, Vic., 3010, Australia.,Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Chris D Thomas
- Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK
| | - Jenny A Hodgson
- Department of Evolution, Ecology and Behaviour, University of Liverpool, Liverpool, L69 7ZB, UK
| | - Michael P Scroggie
- Department of Environment, Land, Water and Planning, Arthur Rylah Institute for Environmental Research, P.O. Box 137, Heidelberg, Vic., 3084, Australia
| | - David S L Ramsey
- Department of Environment, Land, Water and Planning, Arthur Rylah Institute for Environmental Research, P.O. Box 137, Heidelberg, Vic., 3084, Australia
| | - Nick Clemann
- Department of Environment, Land, Water and Planning, Arthur Rylah Institute for Environmental Research, P.O. Box 137, Heidelberg, Vic., 3084, Australia
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36
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Cothran RD, Gervasi SS, Murray C, French BJ, Bradley PW, Urbina J, Blaustein AR, Relyea RA. Carotenoids and amphibians: effects on life history and susceptibility to the infectious pathogen, Batrachochytrium dendrobatidis. CONSERVATION PHYSIOLOGY 2015; 3:cov005. [PMID: 27293690 PMCID: PMC4778475 DOI: 10.1093/conphys/cov005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Revised: 01/02/2015] [Accepted: 01/26/2015] [Indexed: 05/23/2023]
Abstract
Carotenoids are considered beneficial nutrients because they provide increased immune capacity. Although carotenoid research has been conducted in many vertebrates, little research has been done in amphibians, a group that is experiencing global population declines from numerous causes, including disease. We raised two amphibian species through metamorphosis on three carotenoid diets to quantify the effects on life-history traits and post-metamorphic susceptibility to a fungal pathogen (Batrachochytrium dendrobatidis; Bd). Increased carotenoids had no effect on survival to metamorphosis in gray treefrogs (Hyla versicolor) but caused lower survival to metamorphosis in wood frogs [Lithobates sylvaticus (Rana sylvatica)]. Increased carotenoids caused both species to experience slower development and growth. When exposed to Bd after metamorphosis, wood frogs experienced high mortality, and the carotenoid diets had no mitigating effects. Gray treefrogs were less susceptible to Bd, which prevented an assessment of whether carotenoids could mitigate the effects of Bd. Moreover, carotenoids had no effect on pathogen load. As one of only a few studies examining the effects of carotenoids on amphibians and the first to examine potential interactions with Bd, our results suggest that carotenoids do not always serve amphibians in the many positive ways that have become the paradigm in other vertebrates.
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Affiliation(s)
- Rickey D Cothran
- Department of Biological Sciences, Southwestern Oklahoma State University, Weatherford, OK 73096, USA
| | - Stephanie S Gervasi
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA
| | - Cindy Murray
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Beverly J French
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Paul W Bradley
- Environmental Sciences Graduate Program, Oregon State University, Corvallis, OR 97331, USA
| | - Jenny Urbina
- Environmental Sciences Graduate Program, Oregon State University, Corvallis, OR 97331, USA
| | - Andrew R Blaustein
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA
| | - Rick A Relyea
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
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37
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Rollins-Smith LA, Reinert LK, Burrowes PA. Coqui frogs persist with the deadly chytrid fungus despite a lack of defensive antimicrobial peptides. DISEASES OF AQUATIC ORGANISMS 2015; 113:81-83. [PMID: 25667340 DOI: 10.3354/dao02823] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The amphibian skin fungus Batrachochytrium dendrobatidis (Bd) occurs widely in Puerto Rico and is thought to be responsible for the apparent extinction of 3 species of endemic frogs in the genus Eleutherodactylus, known as coquis. To examine immune defenses which may protect surviving species, we induced secretion of skin peptides from adult common coqui frogs E. coqui collected from upland forests at El Yunque. By matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, we were unable to detect peptide signals suggestive of antimicrobial peptides, and enriched peptides showed no capacity to inhibit growth of Bd. Thus, it appears that E. coqui depend on other skin defenses to survive in the presence of this deadly fungus.
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Affiliation(s)
- Louise A Rollins-Smith
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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Holden WM, Reinert LK, Hanlon SM, Parris MJ, Rollins-Smith LA. Development of antimicrobial peptide defenses of southern leopard frogs, Rana sphenocephala, against the pathogenic chytrid fungus, Batrachochytrium dendrobatidis. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2015; 48:65-75. [PMID: 25218643 DOI: 10.1016/j.dci.2014.09.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 09/04/2014] [Accepted: 09/05/2014] [Indexed: 06/03/2023]
Abstract
Amphibian species face the growing threat of extinction due to the emerging fungal pathogen Batrachochytrium dendrobatidis, which causes the disease chytridiomycosis. Antimicrobial peptides (AMPs) produced in granular glands of the skin are an important defense against this pathogen. Little is known about the ontogeny of AMP production or the impact of AMPs on potentially beneficial symbiotic skin bacteria. We show here that Rana (Lithobates) sphenocephala produces a mixture of four AMPs with activity against B. dendrobatidis, and we report the minimum inhibitory concentration (MIC) of synthesized replicates of these four AMPs tested against B. dendrobatidis. Using mass spectrometry and protein quantification assays, we observed that R. sphenocephala does not secrete a mature suite of AMPs until approximately 12 weeks post-metamorphosis, and geographically disparate populations produce a different suite of peptides. Use of norepinephrine to induce maximal secretion significantly reduced levels of culturable skin bacteria.
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Affiliation(s)
- Whitney M Holden
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Laura K Reinert
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Shane M Hanlon
- Department of Biological Sciences, University of Memphis, Memphis, TN 38152, USA
| | - Matthew J Parris
- Department of Biological Sciences, University of Memphis, Memphis, TN 38152, USA
| | - Louise A Rollins-Smith
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA; Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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Walke JB, Becker MH, Loftus SC, House LL, Cormier G, Jensen RV, Belden LK. Amphibian skin may select for rare environmental microbes. ISME JOURNAL 2014; 8:2207-17. [PMID: 24858782 DOI: 10.1038/ismej.2014.77] [Citation(s) in RCA: 169] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 02/26/2014] [Accepted: 04/08/2014] [Indexed: 12/12/2022]
Abstract
Host-microbe symbioses rely on the successful transmission or acquisition of symbionts in each new generation. Amphibians host a diverse cutaneous microbiota, and many of these symbionts appear to be mutualistic and may limit infection by the chytrid fungus, Batrachochytrium dendrobatidis, which has caused global amphibian population declines and extinctions in recent decades. Using bar-coded 454 pyrosequencing of the 16S rRNA gene, we addressed the question of symbiont transmission by examining variation in amphibian skin microbiota across species and sites and in direct relation to environmental microbes. Although acquisition of environmental microbes occurs in some host-symbiont systems, this has not been extensively examined in free-living vertebrate-microbe symbioses. Juvenile bullfrogs (Rana catesbeiana), adult red-spotted newts (Notophthalmus viridescens), pond water and pond substrate were sampled at a single pond to examine host-specificity and potential environmental transmission of microbiota. To assess population level variation in skin microbiota, adult newts from two additional sites were also sampled. Cohabiting bullfrogs and newts had distinct microbial communities, as did newts across the three sites. The microbial communities of amphibians and the environment were distinct; there was very little overlap in the amphibians' core microbes and the most abundant environmental microbes, and the relative abundances of OTUs that were shared by amphibians and the environment were inversely related. These results suggest that, in a host species-specific manner, amphibian skin may select for microbes that are generally in low abundance in the environment.
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Affiliation(s)
- Jenifer B Walke
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | - Matthew H Becker
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | - Stephen C Loftus
- Department of Statistics, Virginia Tech, Blacksburg, Virginia, USA
| | - Leanna L House
- Department of Statistics, Virginia Tech, Blacksburg, Virginia, USA
| | - Guy Cormier
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | - Roderick V Jensen
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | - Lisa K Belden
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
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The interaction of aurein 2.5 with fungal membranes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2014; 43:255-64. [PMID: 24728560 DOI: 10.1007/s00249-014-0959-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 03/21/2014] [Accepted: 03/31/2014] [Indexed: 12/27/2022]
Abstract
Aurein 2.5 (GLFDIVKKVVGAFGSL-NH2) is an antimicrobial peptide, which was seen to have activity against Stachybotris chartarum, Penicillium roseopurpureum and Aspergillus flavus with minimum fungicidal concentrations in the range 250-500 μM. S. chartarum showed enhanced susceptibility to lysis as compared to P. roseopurpureum and A. flavus, (44, 26 and 28 % respectively). Monolayers formed from lipid membrane extracts derived from S. chartarum, P. roseopurpureum and A. flavus showed maximal surface pressure changes of 13.5, 10.3 and 10.2 mN m(-1) respectively. However, aurein 2.5 adopted similar levels of α-helical structure (circa 45 %) in the presence of vesicles formed from membrane lipid extracts derived from all three fungi. These data imply that differential activity is not due to targeting and membrane association but linked to the ability of the bound peptide to lyse the cells. At sterol levels mimetic of eukaryotic systems, high levels of α-helical structure (circa 50 %) were also observed and hence similar binding. However, enhanced sterol levels (>0.6) led to a reduction in monolayer membrane interaction, suggesting that the sterols influence efficacy. Consistent with this suggestion, thermodynamic analysis showed that the peptide was able to destabilise model fungal monolayers, as indicated by negative values of ∆Gmix.
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Küng D, Bigler L, Davis LR, Gratwicke B, Griffith E, Woodhams DC. Stability of microbiota facilitated by host immune regulation: informing probiotic strategies to manage amphibian disease. PLoS One 2014; 9:e87101. [PMID: 24489847 PMCID: PMC3906108 DOI: 10.1371/journal.pone.0087101] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 12/19/2013] [Indexed: 01/16/2023] Open
Abstract
Microbial communities can augment host immune responses and probiotic therapies are under development to prevent or treat diseases of humans, crops, livestock, and wildlife including an emerging fungal disease of amphibians, chytridiomycosis. However, little is known about the stability of host-associated microbiota, or how the microbiota is structured by innate immune factors including antimicrobial peptides (AMPs) abundant in the skin secretions of many amphibians. Thus, conservation medicine including therapies targeting the skin will benefit from investigations of amphibian microbial ecology that provide a model for vertebrate host-symbiont interactions on mucosal surfaces. Here, we tested whether the cutaneous microbiota of Panamanian rocket frogs, Colostethus panamansis, was resistant to colonization or altered by treatment. Under semi-natural outdoor mesocosm conditions in Panama, we exposed frogs to one of three treatments including: (1) probiotic - the potentially beneficial bacterium Lysinibacillus fusiformis, (2) transplant – skin washes from the chytridiomycosis-resistant glass frog Espadarana prosoblepon, and (3) control – sterile water. Microbial assemblages were analyzed by a culture-independent T-RFLP analysis. We found that skin microbiota of C. panamansis was resistant to colonization and did not differ among treatments, but shifted through time in the mesocosms. We describe regulation of host AMPs that may function to maintain microbial community stability. Colonization resistance was metabolically costly and microbe-treated frogs lost 7–12% of body mass. The discovery of strong colonization resistance of skin microbiota suggests a well-regulated, rather than dynamic, host-symbiont relationship, and suggests that probiotic therapies aiming to enhance host immunity may require an approach that circumvents host mechanisms maintaining equilibrium in microbial communities.
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Affiliation(s)
- Denise Küng
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Laurent Bigler
- Institute of Organic Chemistry, University of Zurich, Zurich, Switzerland
| | - Leyla R. Davis
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Brian Gratwicke
- Center for Species Survival, Conservation and Science, National Zoological Park, Smithsonian Institution, Washington DC, United States of America
| | - Edgardo Griffith
- El Valle Amphibian Conservation Center, El Valle, República de Panamá
| | - Douglas C. Woodhams
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
- Smithsonian Tropical Research Institute, Balboa, Ancón, Panamá, República de Panamá
- * E-mail:
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Skin Gland Morphology and Secretory Peptides in NaturalizedLitoriaSpecies in New Zealand. J HERPETOL 2013. [DOI: 10.1670/12-246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Holden WM, Fites JS, Reinert LK, Rollins-Smith LA. Nikkomycin Z is an effective inhibitor of the chytrid fungus linked to global amphibian declines. Fungal Biol 2013; 118:48-60. [PMID: 24433676 DOI: 10.1016/j.funbio.2013.11.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 10/31/2013] [Accepted: 11/05/2013] [Indexed: 11/16/2022]
Abstract
Fungal infections in humans, wildlife, and plants are a growing concern because of their devastating effects on human and ecosystem health. In recent years, populations of many amphibian species have declined, and some have become extinct due to chytridiomycosis caused by the fungal pathogen Batrachochytrium dendrobatidis. For some endangered amphibian species, captive colonies are the best intermediate solution towards eventual reintroduction, and effective antifungal treatments are needed to cure chytridiomycosis and limit the spread of this pathogen in such survival assurance colonies. Currently, the best accepted treatment for infected amphibians is itraconazole, but its toxic side effects reduce its usefulness for many species. Safer antifungal treatments are needed for disease control. Here, we show that nikkomycin Z, a chitin synthase inhibitor, dramatically alters the cell wall stability of B. dendrobatidis cells and completely inhibits growth of B. dendrobatidis at 250 μM. Low doses of nikkomycin Z enhanced the effectiveness of natural antimicrobial skin peptide mixtures tested in vitro. These studies suggest that nikkomycin Z would be an effective treatment to significantly reduce the fungal burden in frogs infected by B. dendrobatidis.
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Affiliation(s)
- Whitney M Holden
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
| | - J Scott Fites
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA.
| | - Laura K Reinert
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
| | - Louise A Rollins-Smith
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA; Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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Ebrahimipour GH, Khosravibabadi Z, Sadeghi H, Aliahmadi A. Isolation, Partial Purification and Characterization of an Antimicrobial Compound, Produced by Bacillus atrophaeus. Jundishapur J Microbiol 2013; 7:e11802. [PMID: 25485057 PMCID: PMC4255372 DOI: 10.5812/jjm.11802] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Revised: 12/01/2013] [Accepted: 12/25/2013] [Indexed: 01/11/2023] Open
Abstract
Background: Antibiotics are usually assumed as secondary metabolites produced during the idiophase of microbial growth, which can kill or inhibit the growth of other microorganisms. Nowadays, indiscriminate use of antibiotics has resulted in resistant microorganisms. Therefore, screening researches on products with antimicrobial activities are necessary. Objectives: To find new antibiotics to defend against pathogenic microorganisms resistant to common antibiotics, the bacterium isolated from skin of the frog called Rana ridibunda was studied for its antimicrobial activities. Materials and Methods: An antibiotic-producing bacterium was isolated from the frog skin. The bacterium was identified based on 16SrDNA sequencing and biochemical and morphological characteristics. Antimicrobial activity of the culture supernatant was examined against laboratorial standard bacteria by disc diffusion and minimum inhibitory concentration (MIC) methods. To characterize the produced antimicrobial compound, the culture supernatant of the bacterium was washed by chloroform and dried at 40°C; then, the antimicrobial substance was extracted by methanol and acetone and detected by bioautography on silica gel plates. Dialysis tube was used to find the molecular weight of this substance. Results: The isolated bacterium was identified as a new strain of Bacillus atrophaeus. The antimicrobial substance exhibited heat stability between 25ºC and 100ºC and was active in a broad pH range from 2.0 to 11.0. The bioautography assay showed that methanol was the optimum solvent for the extraction of antimicrobial substance. The dialysis tube indicated that the antimicrobial substance weight was less than 1 kDa and the compound did not precipitate with ammonium sulfate. Conclusions: This study showed that some properties of antimicrobial substances produced by the GA strain differed from other peptide antibiotics produced by the genus Bacillus such as bacitracin, which increases the likelihood of its novelty.
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Affiliation(s)
| | - Zahra Khosravibabadi
- Department of Microbiology, Faculty of Biological Sciences, Shahid Beheshti University, Tehran, IR Iran
- Corresponding author: Zahra Khosravibabadi, Department of Microbiology, Faculty of Biological Sciences, ShahidBeheshti University, Tehran, IR Iran. Tel: +98-2129902706, Fax: +98-2122431664, E-mail:
| | - Hossein Sadeghi
- Department of Microbiology, Faculty of Biological Sciences, Shahid Beheshti University, Tehran, IR Iran
| | - Atusa Aliahmadi
- Department of Microbiology, Research Institute of Medical Plants and Drug, Shahid Beheshti University, Tehran, IR Iran
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Groner ML, Buck JC, Gervasi S, Blaustein AR, Reinert LK, Rollins-Smith LA, Bier ME, Hempel J, Relyea RA. Larval exposure to predator cues alters immune function and response to a fungal pathogen in post-metamorphic wood frogs. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2013; 23:1443-1454. [PMID: 24147415 DOI: 10.1890/12-1572.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
For the past several decades, amphibian populations have been decreasing around the globe at an unprecedented rate. Batrachochytrium dendrobatidis (Bd), the fungal pathogen that causes chytridiomycosis in amphibians, is contributing to amphibian declines. Natural and anthropogenic environmental factors are hypothesized to contribute to these declines by reducing the immunocompetence of amphibian hosts, making them more susceptible to infection. Antimicrobial peptides (AMPs) produced in the granular glands of a frog's skin are thought to be a key defense against Bd infection. These peptides may be a critical immune defense during metamorphosis because many acquired immune functions are suppressed during this time. To test if stressors alter AMP production and survival of frogs exposed to Bd, we exposed wood frog (Lithobates sylvaticus) tadpoles to the presence or absence of dragonfly predator cues crossed with a single exposure to three nominal concentrations of the insecticide malathion (0, 10, or 100 parts per billion [ppb]). We then exposed a subset of post-metamorphic frogs to the presence or absence of Bd zoospores and measured frog survival. Although predator cues and malathion had no effect on survival or size at metamorphosis, predator cues increased the time to metamorphosis by 1.5 days and caused a trend of a 20% decrease in hydrophobic skin peptides. Despite this decrease in peptides determined shortly after metamorphosis, previous exposure to predator cues increased survival in both Bd-exposed and unexposed frogs several weeks after metamorphosis. These results suggest that exposing tadpoles to predator cues confers fitness benefits later in life.
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Affiliation(s)
- Maya L Groner
- Center for Veterinary Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Prince Edward Island C1A 4P3, Canada.
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Dennison SR, Harris F, Morton LHG, Phoenix DA. Antimicrobial activity of aurein 2.5 against yeasts. FEMS Microbiol Lett 2013; 346:140-5. [PMID: 23841919 DOI: 10.1111/1574-6968.12212] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 06/06/2013] [Accepted: 07/03/2013] [Indexed: 12/28/2022] Open
Abstract
Fungal infections with multiple resistance to conventional antifungals are increasingly becoming a medical problem, and there is an urgent need for new antifungal compounds with novel mechanisms of action. Here, we show that aurein 2.5, a naturally occurring peptide antibiotic, displays activity against the fungal strains: Rhodotorula rubra and Schizosaccharomyces pombe (MICs < 130 μM). The peptide adopted high levels of membrane-interactive α-helical structure (> 65%) in the presence of lipid membranes derived from these organisms and showed strong propensities to penetrate (π ≥ 13 mN m(-1) ) and lyse them (> 70%). Based on these data, we suggest that aurein 2.5 kills yeasts via membranolytic mechanisms and may act as a template for the development of therapeutically useful antifungal agents.
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Affiliation(s)
- Sarah R Dennison
- School of Pharmacy and Biomedical Sciences, University of Central Lancashire, Preston, UK
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Pask JD, Cary TL, Rollins-Smith LA. Skin peptides protect juvenile leopard frogs (Rana pipiens) against chytridiomycosis. ACTA ACUST UNITED AC 2013; 216:2908-16. [PMID: 23580715 DOI: 10.1242/jeb.084145] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
One issue of great concern for the scientific community is the continuing loss of diverse amphibian species on a global scale. Amphibian populations around the world are experiencing serious losses due to the chytrid fungus, Batrachochytrium dendrobatidis. This pathogen colonizes the skin, leading to the disruption of ionic balance and eventual cardiac arrest. In many species, antimicrobial peptides secreted into the mucus are thought to contribute to protection against colonization by skin pathogens. Although it is generally thought that antimicrobial peptides are an important component of innate immune defenses against B. dendrobatidis, much of the current evidence relies on correlations between effective antimicrobial peptide defenses and species survival. There have been few studies to directly demonstrate that antimicrobial peptides play a role. Using the northern leopard frog, Rana pipiens, we show here that injection of noradrenaline (norepinephrine) brings about a long-term depletion of skin peptides (initial concentrations do not recover until after day 56). When peptide stores recovered, the renewed peptides were similar in composition to the initial peptides as determined by MALDI-TOF mass spectrometry and in activity against B. dendrobatidis as determined by growth inhibition assays. Newly metamorphosed froglets depleted of their peptide stores and exposed to B. dendrobatidis died more rapidly than B. dendrobatidis-exposed froglets with their peptides intact. Thus, antimicrobial peptides in the skin mucus appear to provide some resistance to B. dendrobatidis infections, and it is important for biologists to recognize that this defense is especially important for newly metamorphosed frogs in which the adaptive immune system is still immature.
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Affiliation(s)
- James D Pask
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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Bell SC, Alford RA, Garland S, Padilla G, Thomas AD. Screening bacterial metabolites for inhibitory effects against Batrachochytrium dendrobatidis using a spectrophotometric assay. DISEASES OF AQUATIC ORGANISMS 2013; 103:77-85. [PMID: 23482387 DOI: 10.3354/dao02560] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Certain bacteria present on frog skin can prevent infection by the pathogenic fungus Batrachochytrium dendrobatidis (Bd), conferring disease resistance. Previous studies have used agar-based in vitro challenge assays to screen bacteria for Bd-inhibitory activity and to identify candidates for bacterial supplementation trials. However, agar-based assays can be difficult to set up and to replicate reliably. To overcome these difficulties, we developed a semi-quantitative spectrophotometric challenge assay technique. Cell-free supernatants were prepared from filtered bacterial cultures and added to 96-well plates in replicated wells containing Bd zoospores suspended in tryptone-gelatin hydrolysate-lactose (TGhL) broth medium. Plates were then read daily on a spectrophotometer until positive controls reached maximum growth in order to determine growth curves for Bd. We tested the technique by screening skin bacteria from the Australian green-eyed tree frog Litoria serrata. Of bacteria tested, 31% showed some degree of Bd inhibition, while some may have promoted Bd growth, a previously unknown effect. Our cell-free supernatant challenge assay technique is an effective in vitro method for screening bacterial isolates for strong Bd-inhibitory activity. It contributes to the expanding field of bioaugmentation research, which could play a significant role in mitigating the effects of chytridiomycosis on amphibians around the world.
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Affiliation(s)
- Sara C Bell
- School of Marine and Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia.
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Gervasi S, Gondhalekar C, Olson DH, Blaustein AR. Host identity matters in the amphibian-Batrachochytrium dendrobatidis system: fine-scale patterns of variation in responses to a multi-host pathogen. PLoS One 2013; 8:e54490. [PMID: 23382904 PMCID: PMC3554766 DOI: 10.1371/journal.pone.0054490] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 12/12/2012] [Indexed: 11/19/2022] Open
Abstract
Species composition within ecological assemblages can drive disease dynamics including pathogen invasion, spread, and persistence. In multi-host pathogen systems, interspecific variation in responses to infection creates important context dependency when predicting the outcome of disease. Here, we examine the responses of three sympatric host species to a single fungal pathogen, Batrachochytrium dendrobatidis, which is associated with worldwide amphibian population declines and extinctions. Using an experimental approach, we show that amphibian species from three different genera display significant differences in patterns of pathgen-induced mortality as well as the magnitude and temporal dynamics of infection load. We exposed amphibians to one of four inoculation dose treatments at both larval and post- metamorphic stages and quantified infection load on day 8 and day 15 post-inoculation. Of the three species examined, only one (the Pacific treefrog; Pseudacris regilla) displayed "dose-dependent" responses; survival was reduced and infection load was elevated as inoculation dose was increased. We observed a reduction in survival but no differences in infection load across pathogen treatments in Cascades frogs (Rana cascadae). Western toads (Anaxyrus boreas) displayed differences in infection load but no differences in survival across pathogen treatments. Within species, responses to the pathogen varied with life history stage, and the most heavily infected species at the larval stage was different from the most heavily infected species at the post-metamorphic stage. Temporal changes in infection load were species and life history stage-specific. We show that variation in susceptibility to this multi-host pathogen is complex when viewed at a fine-scale and may be mediated through intrinsic host traits.
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Affiliation(s)
- Stephanie Gervasi
- Department of Zoology, Oregon State University, Corvallis, Oregon, USA.
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50
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Daum JM, Davis LR, Bigler L, Woodhams DC. Hybrid advantage in skin peptide immune defenses of water frogs (Pelophylax esculentus) at risk from emerging pathogens. INFECTION GENETICS AND EVOLUTION 2012; 12:1854-64. [DOI: 10.1016/j.meegid.2012.07.024] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 07/30/2012] [Accepted: 07/31/2012] [Indexed: 02/08/2023]
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