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Ballestero E, Bolaños F, Ruepert C, Jiménez R, Bonilla F, Sasa M. Immunological and physiological responses to predation risk and sublethal concentrations of chlorothalonil and β-endosulfan in Lithobates taylori (Anura: Ranidae) tadpoles. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2024; 275:107071. [PMID: 39236548 DOI: 10.1016/j.aquatox.2024.107071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2024] [Revised: 08/11/2024] [Accepted: 08/29/2024] [Indexed: 09/07/2024]
Abstract
Pesticide exposure and its interaction with other natural stressors can play a role in amphibian population declines because disruptions in stress hormone regulatory mechanisms may inhibit immune responses during metamorphosis. Here, we determined the interactive effects of predation risk and sublethal concentration of two pesticides on immunological and physiological responses in tadpoles of the tropical frog Lithobates taylori. Using mesocosms, we used chronic exposure to three levels of chlorothalonil and β-endosulfan in the presence or absence of Odonate larvae. Our results show that β-endosulfan in high concentrations reduced the weight of the tadpoles and increased the neutrophil count and corticosterone (CORT) levels. Larval development was accelerated by high concentrations of chlorothalonil. Also, this pesticide in low and high concentrations increases the absolute values of lymphocytes. Tadpoles exposed to chlorothalonil increased the numbers of monocytes (in low concentrations), and lymphocytes (in high and low concentrations). The interactions of the low concentrations of both pesticides with and without the predator's presence also increased the number of lymphocytes. A combination of pesticides increases the number of lymphocytes in the blood due to synergistic cytotoxicity. This study proves that β- endosulfan elevates circulating CORT and thus generates physiological stress in tadpoles. Given that both pesticides are widely used within the distribution of L. taylori in Costa Rica, it is likely that tadpoles' development and immune function are altered by pesticide use. In combination with stressors such as emerging diseases and altered precipitation regimes, widespread agrochemical uses likely caused this species enigmatic decline in recent decades.
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Affiliation(s)
- Erick Ballestero
- Escuela de Biología, Universidad de Costa Rica, San José 2060, Costa Rica; Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José 2060, Costa Rica.
| | - Federico Bolaños
- Escuela de Biología, Universidad de Costa Rica, San José 2060, Costa Rica
| | - Clemens Ruepert
- Instituto Regional de Estudios en Sustancias Tóxicas, Universidad Nacional, Heredia 3000, Costa Rica
| | - Randall Jiménez
- Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm, 89069 Ulm, Germany
| | - Fabian Bonilla
- Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José 2060, Costa Rica
| | - Mahmood Sasa
- Escuela de Biología, Universidad de Costa Rica, San José 2060, Costa Rica; Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José 2060, Costa Rica
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O'Dwyer K, Milotic D, Milotic M, Koprivnikar J. Behave yourself: effects of exogenous-glucocorticoid exposure on larval amphibian anti-parasite behaviour and physiology. Oecologia 2024; 205:95-106. [PMID: 38689180 DOI: 10.1007/s00442-024-05547-6] [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] [Received: 04/18/2022] [Accepted: 03/30/2024] [Indexed: 05/02/2024]
Abstract
Parasites represent a ubiquitous threat for most organisms, requiring potential hosts to invest in a range of strategies to defend against infection-these include both behavioural and physiological mechanisms. Avoidance is an essential first line of defence, but this behaviour may show a trade-off with host investment in physiological immunity. Importantly, while environmental stressors can lead to elevated hormones in vertebrates, such as glucocorticoids, that can reduce physiological immunity in certain contexts, behavioural defences may also be compromised. Here, we investigate anti-parasite behaviour and immune responses against a trematode (flatworm) parasite by larval amphibians (tadpoles) exposed or not to a simulated general stressor in the form of exogenous corticosterone. Tadpoles that were highly active in the presence of the trematode infectious stage (cercariae) had lower infection loads, and parasite loads from tadpoles treated only with dechlorinated water were significantly lower than those exposed to corticosterone or the solvent control. However, treatment did not affect immunity as measured through white blood-cell profiles, and there was no relationship between the latter and anti-parasite behaviour. Our results suggest that a broad range of stressors could increase host susceptibility to infection through altered anti-parasite behaviours if they elevate endogenous glucocorticoids, irrespective of physiological immunity effects. How hosts defend themselves against parasitism in the context of multiple challenges represents an important topic for future research, particularly as the risk posed by infectious diseases is predicted to increase in response to ongoing environmental change.
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Affiliation(s)
- Katie O'Dwyer
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, ON, Canada.
- Marine and Freshwater Research Centre, Atlantic Technological University, Old Dublin Road, Co., Galway, Ireland.
| | - Dino Milotic
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, ON, Canada
- Harry Butler Institute, Murdoch University, Perth, WA, Australia
| | - Marin Milotic
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, ON, Canada
- Harry Butler Institute, Murdoch University, Perth, WA, Australia
| | - Janet Koprivnikar
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, ON, Canada
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Emerson KJ, Woodley SK. Something in the water: aquatic microbial communities influence the larval amphibian gut microbiota, neurodevelopment and behaviour. Proc Biol Sci 2024; 291:20232850. [PMID: 38412968 PMCID: PMC10898966 DOI: 10.1098/rspb.2023.2850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/29/2024] Open
Abstract
Microorganisms colonize the gastrointestinal tract of animals and establish symbiotic host-associated microbial communities that influence vertebrate physiology. More specifically, these gut microbial communities influence neurodevelopment through the microbiota-gut-brain (MGB) axis. We tested the hypothesis that larval amphibian neurodevelopment is affected by the aquatic microbial community present in their housing water. Newly hatched Northern Leopard Frog (Lithobates pipiens) tadpoles were raised in pond water that was unmanipulated (natural) or autoclaved. Tadpoles raised in autoclaved pond water had a gut microbiota with reduced bacterial diversity and altered community composition, had decreased behavioural responses to sensory stimuli, were larger in overall body mass, had relatively heavier brains and had altered brain shape when compared with tadpoles raised in natural pond water. Further, the diversity and composition of the gut microbiota were associated with tadpole behavioural responses and brain measurements. Our results suggest that aquatic microbial communities shape tadpole behaviour and brain development, providing strong support for the occurrence of the MGB axis in amphibians. Lastly, the dramatic role played by aquatic microbial communities on vertebrate neurodevelopment and behaviour should be considered in future wildlife conservation efforts.
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Affiliation(s)
- Kyle J Emerson
- Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15220, USA
| | - Sarah K Woodley
- Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15220, USA
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Antipredator responses of Indosylvirana indica tadpoles do not match the level of predation risk. J Biosci 2022. [DOI: 10.1007/s12038-022-00317-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Petrullo L, Delaney D, Boutin S, McAdam AG, Lane JE, Boonstra R, Palme R, Dantzer B. The glucocorticoid response to environmental change is not specific to agents of natural selection in wild red squirrels. Horm Behav 2022; 146:105262. [PMID: 36191397 DOI: 10.1016/j.yhbeh.2022.105262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 08/30/2022] [Accepted: 09/07/2022] [Indexed: 11/04/2022]
Abstract
Evolutionary endocrinology aims to understand how natural selection shapes endocrine systems and the degree to which endocrine systems themselves can induce phenotypic responses to environmental changes. Such responses may be specialized in that they reflect past selection for responsiveness only to those ecological factors that ultimately influence natural selection. Alternatively, endocrine responses may be broad and generalized, allowing organisms to cope with a variety of environmental changes simultaneously. Here, we empirically tested whether the endocrine response of female North American red squirrels (Tamiasciurus hudsonicus) was specialized or generalized. We first quantified the direction and magnitude of natural selection acting on three female life history traits (parturition date, litter size, offspring postnatal growth rate) during 32 years of fluctuations in four potential ecological agents of selection (food availability, conspecific density, predator abundance, and temperature). Only three of the four variables (food, density, and predators) affected patterns of natural selection on female life history traits. We then quantified fecal glucocorticoid metabolites (FGMs) across 7 years and found that all four environmental variables, regardless of their effects on patterns of selection, were associated with glucocorticoid production. Our results provide support for a generalized, rather than specific, glucocorticoid response to environmental change that can integrate across multiple co-occurring environmental stressors.
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Affiliation(s)
- Lauren Petrullo
- Department of Psychology, University of Michigan, Ann Arbor, MI 48108, USA.
| | - David Delaney
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA
| | - Stan Boutin
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Andrew G McAdam
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA
| | - Jeffrey E Lane
- Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
| | - Rudy Boonstra
- Department of Biological Sciences, Centre for the Neurobiology of Stress, University of Toronto Scarborough, Toronto, ON M1C 1A6, Canada
| | - Rupert Palme
- Unit of Physiology, Pathophysiology and Experimental Endocrinology, Department of Biomedical Sciences, University of Veterinary Medicine Vienna, Veterina ̈rplatz 1, Vienna 1210, Austria
| | - Ben Dantzer
- Department of Psychology, University of Michigan, Ann Arbor, MI 48108, USA; Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48108, USA
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Paul B, Sterner ZR, Bhawal R, Anderson ET, Zhang S, Buchholz DR. Impaired negative feedback and death following acute stress in glucocorticoid receptor knockout Xenopus tropicalis tadpoles. Gen Comp Endocrinol 2022; 326:114072. [PMID: 35697317 DOI: 10.1016/j.ygcen.2022.114072] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 06/03/2022] [Accepted: 06/07/2022] [Indexed: 11/21/2022]
Abstract
Blood glucocorticoid levels are regulated by the hypothalamo-pituitary-adrenal/interrenal axis (HPA axis in mammals, HPI axis in amphibians), and negative feedback by glucocorticoid signaling is a key player in that regulation. Glucocorticoid and mineralocorticoid receptors (GR and MR) mediate negative feedback in mammals, but little is known about nuclear receptor-mediated feedback in amphibians. Because amphibians have only one corticosteroidogenic cell type responsible for glucocorticoid and mineralocorticoid production, we hypothesized that GR knockout (GRKO) tadpoles have elevated levels of glucocorticoids and mineralocorticoids as well as axis components regulating their production. We also examined the response to stress and potential for increased aldosterone signaling in GRKO tadpoles. We found that GRKO tadpoles have severe hyperactivity of the HPI axis, namely high mRNA expression levels of pomc, cyp17a1, cyp21a2, cyp11b2, and star, and high tissue content of corticosterone, aldosterone, 17-hydroxyprogesterone, 21-deoxycortisol, and progesterone. Such aberrant HPI activity was accompanied by reduced survival after acute temperature shock and shaking stress. Like mammalian models of HPA hyperactivity, GRKO tadpoles have high MR mRNA expression levels in brain, kidney, heart, and skin and high levels of the inflammatory cytokine tnf-α and the profibrotic factor tgf-β in kidneys. This study showed GR is critical for negative feedback to the amphibian HPI axis and for survival from acute stressors. This study also showed GRKO tadpoles exhibit altered expression/overproduction of regulators of salt-water homeostasis and associated biomarkers of kidney disease.
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Affiliation(s)
- Bidisha Paul
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, United States
| | - Zachary R Sterner
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, United States
| | - Ruchika Bhawal
- Proteomics and Metabolomics Facility, Institute of Biotechnology, Cornell University, Ithaca, NY 14853, United States
| | - Elizabeth T Anderson
- Proteomics and Metabolomics Facility, Institute of Biotechnology, Cornell University, Ithaca, NY 14853, United States
| | - Sheng Zhang
- Proteomics and Metabolomics Facility, Institute of Biotechnology, Cornell University, Ithaca, NY 14853, United States
| | - Daniel R Buchholz
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, United States.
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Regueira E, O'Donohoe MEA, Pavón Novarin M, Michou Etcheverría GC, Tropea C, Hermida GN. Integrating morphology and physiology of the key endocrine organ during tadpole development: The interrenal gland. J Anat 2022; 241:1357-1370. [PMID: 36056596 DOI: 10.1111/joa.13759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 08/09/2022] [Accepted: 08/17/2022] [Indexed: 11/26/2022] Open
Abstract
Indirect development is widespread in anurans and is considered an ancestral condition. The metamorphosis of larvae into juveniles involves highly coordinated morphological, physiological, biochemical, and behavioral changes, promoted by the thyroid hormone and interrenal corticosteroids. Stress response to environmental changes is also mediated by corticosteroids, affecting the timing and rate of metamorphosis and leading to great developmental plasticity in tadpoles. Given the potential effect of interrenal gland ontogeny alterations on metamorphosis and the lack of studies addressing both the morphology and endocrinology of this gland in tadpoles, we present corticosterone (CORT) production and histological changes through the ontogeny of interrenal gland in the generalized pond-type tadpole of Rhinella arenarum (Anura, Bufonidae). This species shows the highest concentration of whole-body CORT by the early climax when drastic metamorphic changes begin. This is coincident with the morphological differentiation of steroidogenic cells and the formation of interrenal cords. By this stage, steroidogenic cells have a shrunken cytoplasm, with a significantly higher nucleus-to-cell diameter ratio. The lowest CORT concentration during premetamorphosis and late climax is associated with small undifferentiated cells with lipid inclusions surrounding large blood vessels between kidneys, and with cords of differentiated steroidogenic cells with a significantly lower nucleus-to-cell diameter ratio, respectively. Our study characterizes the morphological and physiological pattern of interrenal gland development, showing an association between certain histological and morphometric characteristics and CORT levels. Variations in this morpho-physiological pattern should be considered when studying the phenotypic plasticity or variable growth rates of tadpoles.
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Affiliation(s)
- Eleonora Regueira
- Laboratorio Biología de Anfibios - Histología Animal, Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, CABA, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas, CABA, Argentina
| | - M E Ailín O'Donohoe
- Laboratorio Biología de Anfibios - Histología Animal, Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, CABA, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas, CABA, Argentina
| | - Mariela Pavón Novarin
- Laboratorio Biología de Anfibios - Histología Animal, Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, CABA, Argentina
| | - Gabriela C Michou Etcheverría
- Laboratorio Biología de Anfibios - Histología Animal, Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, CABA, Argentina
| | - Carolina Tropea
- Consejo Nacional de Investigaciones Científicas y Técnicas, CABA, Argentina.,Laboratorio de Biología de la Reproducción y el Crecimiento de Crustáceos Decápodos, Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA), Universidad de Buenos Aires, CABA, Argentina
| | - Gladys N Hermida
- Laboratorio Biología de Anfibios - Histología Animal, Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, CABA, Argentina
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