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Humphries JE, Lanctôt CM, McCallum HI, Newell DA, Grogan LF. Chytridiomycosis causes high amphibian mortality prior to the completion of metamorphosis. ENVIRONMENTAL RESEARCH 2024; 247:118249. [PMID: 38244972 DOI: 10.1016/j.envres.2024.118249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Revised: 01/09/2024] [Accepted: 01/17/2024] [Indexed: 01/22/2024]
Abstract
Amphibian populations are undergoing extensive declines globally. The fungal disease chytridiomycosis, caused by the pathogenic fungus Batrachochytrium dendrobatidis (Bd), is a primary contributor to these declines. The amphibian metamorphic stages (Gosner stages 42-46) are particularly vulnerable to a range of stressors, including Bd. Despite this, studies that explicitly examine host response to chytridiomycosis throughout the metamorphic stages are lacking. We aimed to determine how Bd exposure during the larval stages impacts metamorphic development and infection progression in the endangered Fleay's barred frog (Mixophyes fleayi). We exposed M. fleayi to Bd during pro-metamorphosis (Gosner stages 35-38) and monitored infection dynamics throughout metamorphosis. We took weekly morphological measurements (weight, total body length, snout-vent-length and Gosner stage) and quantified Bd load using qPCR. While we observed minimal impact of Bd infection on animal growth and development, Bd load varied throughout ontogeny, with an infection load plateau during the tadpole stages (Gosner stages 35-41) and temporary infection clearance at Gosner stage 42. Bd load increased exponentially between Gosner stages 42 and 45, with most exposed animals becoming moribund at Gosner stage 45, prior to the completion of metamorphosis. There was variability in infection outcome of exposed individuals, with a subgroup of animals (n = 5/29) apparently clearing their infection while the majority (n = 21/29) became moribund with high infection burdens. This study demonstrates the role that metamorphic restructuring plays in shaping Bd infection dynamics and raises the concern that substantial Bd-associated mortality could be overlooked in the field due to the often cryptic nature of these latter metamorphic stages. We recommend future studies that directly examine the host immune response to Bd infection throughout metamorphosis, incorporating histological and molecular methods to elucidate the mechanisms responsible for the observed trends.
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Affiliation(s)
- Josephine E Humphries
- School of Environment and Science, Griffith University, Southport, Queensland 4222, Australia; Centre for Planetary Health and Food Security, Griffith University, Southport, Queensland 4222, Australia.
| | - Chantal M Lanctôt
- School of Environment and Science, Griffith University, Southport, Queensland 4222, Australia; Australian Rivers Institute, Griffith University, Southport, Queensland 4222, Australia
| | - Hamish I McCallum
- Centre for Planetary Health and Food Security, Griffith University, Southport, Queensland 4222, Australia
| | - David A Newell
- Faculty of Science and Engineering, Southern Cross University, Lismore, New South Wales 2480, Australia
| | - Laura F Grogan
- School of Environment and Science, Griffith University, Southport, Queensland 4222, Australia; Centre for Planetary Health and Food Security, Griffith University, Southport, Queensland 4222, Australia
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Mantzana-Oikonomaki V, Desreveaux A, Preißler K, Maan ME, Spitzen-van der Sluijs A, Sabino-Pinto J. FIRST RECORD OF BATRACHOCHYTRIUM DENDROBATIDIS IN THE NORTHERN NETHERLANDS. J Parasitol 2024; 110:11-16. [PMID: 38232760 DOI: 10.1645/22-126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2024] Open
Abstract
Batrachochytrium dendrobatidis (Bd) infects amphibians and has been linked to the decline of hundreds of anuran amphibians all over the world. In the province of Groningen in the Netherlands, this fungal pathogen was not detected before this study. To determine whether Groningen was Bd-free, we surveyed 12 locations in this province in 2020 and 2021. Samples were then used to quantify the presence of Bd with a qPCR assay. In total, 2 out of 110 (∼0.02%) collected in 2020 and 11 out of 249 samples collected in 2021 tested positive for Bd. Infected amphibians were found in 4 out of the 12 sites, and the prevalence of Bd was estimated at 4% for both years combined. Our study provides the first record of Bd in Groningen, and we hypothesize that Bd is present throughout the Netherlands in regions currently considered "Bd-free." Furthermore, we warn scientists and policymakers to be apprehensive when calling a site free from Bd when sampling is limited or not recent.
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Affiliation(s)
- Vasiliki Mantzana-Oikonomaki
- University of Groningen, GELIFES (Groningen Institute for Evolutionary Life Sciences), Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Anne Desreveaux
- University of Groningen, GELIFES (Groningen Institute for Evolutionary Life Sciences), Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Kathleen Preißler
- Institute of Biology, Molecular Evolution and Systematics of Animals, University of Leipzig, Talstraße 33, 04103 Leipzig, Germany
| | - Martine E Maan
- University of Groningen, GELIFES (Groningen Institute for Evolutionary Life Sciences), Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Annemarieke Spitzen-van der Sluijs
- Reptile, Amphibian and Fish Conservation Netherlands (RAVON), PO Box 1413, 5601 BK Nijmegen, The Netherlands
- Institute for Water and Wetland Research, Animal Ecology and Physiology, Radboud Universiteit, PO Box 9010, 6500 GL Nijmegen, The Netherlands
| | - Joana Sabino-Pinto
- University of Groningen, GELIFES (Groningen Institute for Evolutionary Life Sciences), Nijenborgh 7, 9747 AG Groningen, The Netherlands
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Ujszegi J, Boros Z, Fodor A, Vajna B, Hettyey A. Metabolites of Xenorhabdus bacteria are potent candidates for mitigating amphibian chytridiomycosis. AMB Express 2023; 13:88. [PMID: 37615904 PMCID: PMC10449739 DOI: 10.1186/s13568-023-01585-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 07/20/2023] [Indexed: 08/25/2023] Open
Abstract
Chytridiomycosis, caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), has caused extreme losses in amphibian biodiversity. Finding bacteria that produce metabolites with antifungal properties may turn out to be invaluable in the fight against this devastating disease. The entomopathogenic bacteria, Xenorhabdus szentirmaii and X. budapestensis produce secondary metabolites that are effective against a wide range of fungal plant pathogens. To assess whether they may also be effective against Bd, we extracted cell-free culture media (CFCM) from liquid cultures of X. szentirmaii and X. budapestensis and tested their ability to inhibit Bd growth in vitro. As a second step, using juvenile common toads (Bufo bufo) experimentally infected with Bd we also tested the in vivo antifungal efficacy of X. szentirmaii CFCM diluted to 2 and 10% (v/v), while also assessing possible malign side effects on amphibians. Results of the in vitro experiment documented highly effective growth inhibition by CFCMs of both Xenorhabdus species. The in vivo experiment showed that treatment with CFCM of X. szentirmaii applied at a dilution of 10% resulted in infection intensities reduced by ca. 73% compared to controls and to juvenile toads treated with CFCM applied at a dilution of 2%. At the same time, we detected no negative side effects of treatment with CFCM on toad survival and development. Our results clearly support the idea that metabolites of X. szentirmaii, and perhaps of several other Xenorhabdus species as well, may prove highly useful for the treatment of Bd infected amphibians.
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Affiliation(s)
- János Ujszegi
- Department of Evolutionary Ecology, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Budapest, Hungary.
- Department of Systematic Zoology and Ecology, Eötvös Loránd University, Budapest, Hungary.
| | - Zsófia Boros
- Department of Evolutionary Ecology, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Budapest, Hungary
- Department of Genetics, Eötvös Loránd University, Budapest, Hungary
- Department of Microbiology, Eötvös Loránd University, Budapest, Hungary
| | - András Fodor
- Department of Genetics, Eötvös Loránd University, Budapest, Hungary
| | - Balázs Vajna
- Department of Microbiology, Eötvös Loránd University, Budapest, Hungary
| | - Attila Hettyey
- Department of Evolutionary Ecology, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Budapest, Hungary
- Department of Systematic Zoology and Ecology, Eötvös Loránd University, Budapest, Hungary
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Üveges B, Kalina C, Szabó K, Móricz ÁM, Holly D, Gabor CR, Hettyey A, Bókony V. Does the Glucocorticoid Stress Response Make Toads More Toxic? An Experimental Study on the Regulation of Bufadienolide Toxin Synthesis. Integr Org Biol 2023; 5:obad021. [PMID: 37435008 PMCID: PMC10331804 DOI: 10.1093/iob/obad021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 05/15/2023] [Accepted: 06/02/2023] [Indexed: 07/13/2023] Open
Abstract
Chemical defense is a crucial component of fitness in many organisms, yet the physiological regulation of defensive toxin synthesis is poorly understood, especially in vertebrates. Bufadienolides, the main defensive compounds of toads, are toxic to many predators and other natural enemies, and their synthesis can be upregulated by stressors, including predation risk, high conspecific density, and pollutants. Thus, higher toxin content may be the consequence of a general endocrine stress response in toads. Therefore, we hypothesized that bufadienolide synthesis may be stimulated by elevated levels of corticosterone (CORT), the main glucocorticoid hormone of amphibians, or by upstream regulators that stimulate CORT production. To test these alternatives, we treated common toad tadpoles with exogenous CORT (exoCORT) or metyrapone (MTP, a CORT-synthesis inhibitor that stimulates upstream regulators of CORT by negative feedback) in the presence or absence of predation cues for 2 or 6 days, and subsequently measured their CORT release rates and bufadienolide content. We found that CORT release rates were elevated by exoCORT, and to a lesser extent also by MTP, regardless of treatment length. Bufadienolide content was significantly decreased by treatment with exoCORT for 6 days but was unaffected by exposure to exoCORT for 2 days or to MTP for either 6 or 2 days. The presence or absence of predation cues affected neither CORT release rate nor bufadienolide content. Our results suggest that changes in bufadienolide synthesis in response to environmental challenges are not driven by CORT but may rather be regulated by upstream hormones of the stress response.
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Affiliation(s)
| | - C Kalina
- Department of Evolutionary Ecology, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Herman Ottó út 15, 1022 Budapest, Hungary
- Department of Ecology, Institute of Biology, University of Veterinary Medicine, István u. 2, 1078 Budapest, Hungary
| | - K Szabó
- Division of Clinical Immunology, Department for Internal Medicine, Faculty of Medicine, University of Debrecen, Móricz Zsigmond út 22, 4032 Debrecen, Hungary
| | - Á M Móricz
- Department of Pathophysiology, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Herman Ottó út 15, 1022 Budapest, Hungary
| | - D Holly
- Department of Evolutionary Ecology, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Herman Ottó út 15, 1022 Budapest, Hungary
| | - C R Gabor
- Department of Evolutionary Ecology, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Herman Ottó út 15, 1022 Budapest, Hungary
- Department of Biology, College of Science and Engineering, Texas State University, 601 University Dr., San Marcos, TX 78666, USA
| | - A Hettyey
- Department of Evolutionary Ecology, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Herman Ottó út 15, 1022 Budapest, Hungary
| | - V Bókony
- Department of Evolutionary Ecology, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Herman Ottó út 15, 1022 Budapest, Hungary
- Department of Ecology, Institute of Biology, University of Veterinary Medicine, István u. 2, 1078 Budapest, Hungary
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Gut Bacterial Communities Vary across Habitats and Their Diversity Increases with Increasing Glucocorticoids in Toad Tadpoles. DIVERSITY 2022. [DOI: 10.3390/d15010023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The gut microbiome is important for host health and can be influenced by environmental and hormonal changes. We studied the interactions between anthropogenic land use, glucocorticoid hormones, and gut bacterial communities in common toads (Bufo bufo). We sampled tadpoles from ponds of three habitat types (natural, agricultural, and urban ponds), examined gut microbiome composition using amplicon sequencing of the 16S rRNA gene, and measured the associated stress physiology using water-borne hormones. Tadpoles from different habitat types significantly differed in bacterial composition. However, bacterial richness, Shannon diversity, and Firmicutes to Bacteroidota ratio did not vary with habitat type. In contrast with other studies, we found a positive correlation between baseline corticosterone release rate and bacterial diversity. Stress response and negative feedback were not significantly correlated with bacterial diversity. These results suggest that, despite alterations in the composition of intestinal bacterial communities due to land-use change, common toad tadpoles in anthropogenic habitats may maintain their physiological health in terms of the “gut-brain axis”.
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Kásler A, Ujszegi J, Holly D, Üveges B, Móricz ÁM, Herczeg D, Hettyey A. Metamorphic common toads keep chytrid infection under control, but at a cost. J Zool (1987) 2022. [DOI: 10.1111/jzo.12974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- A. Kásler
- Lendület Evolutionary Ecology Research Group Centre for Agricultural Research Plant Protection Institute Eötvös Loránd Research Network Budapest Hungary
- Doctoral School of Biology Institute of Biology ELTE Eötvös Loránd University Budapest Hungary
| | - J. Ujszegi
- Lendület Evolutionary Ecology Research Group Centre for Agricultural Research Plant Protection Institute Eötvös Loránd Research Network Budapest Hungary
- Department of Systematic Zoology and Ecology Institute of Biology ELTE Eötvös Loránd University Budapest Hungary
| | - D. Holly
- Lendület Evolutionary Ecology Research Group Centre for Agricultural Research Plant Protection Institute Eötvös Loránd Research Network Budapest Hungary
- Doctoral School of Biology Institute of Biology ELTE Eötvös Loránd University Budapest Hungary
| | - B. Üveges
- Lendület Evolutionary Ecology Research Group Centre for Agricultural Research Plant Protection Institute Eötvös Loránd Research Network Budapest Hungary
- Molecular Ecology and Evolution at Bangor School of Natural Sciences Bangor University Bangor UK
| | - Á. M. Móricz
- Department of Pathophysiology Centre for Agricultural Research Plant Protection Institute Eötvös Loránd Research Network Budapest Hungary
| | - D. Herczeg
- Lendület Evolutionary Ecology Research Group Centre for Agricultural Research Plant Protection Institute Eötvös Loránd Research Network Budapest Hungary
| | - A. Hettyey
- Lendület Evolutionary Ecology Research Group Centre for Agricultural Research Plant Protection Institute Eötvös Loránd Research Network Budapest Hungary
- Department of Systematic Zoology and Ecology Institute of Biology ELTE Eötvös Loránd University Budapest Hungary
- Department of Ecology University of Veterinary Medicine Budapest Hungary
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