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Kijanović A, Vukov T, Mirč M, Mitrović A, Prokić MD, Petrović TG, Radovanović TB, Gavrilović BR, Despotović SG, Gavrić JP, Tomašević Kolarov N. The role of phenotypic plasticity and corticosterone in coping with pond drying conditions in yellow-bellied toad (Bombina variegata, Linnaeus 1758) tadpoles. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2024; 341:753-765. [PMID: 38651613 DOI: 10.1002/jez.2819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 03/29/2024] [Accepted: 04/09/2024] [Indexed: 04/25/2024]
Abstract
Amphibian larvae inhabiting temporary ponds often exhibit the capacity to accelerate development and undergo metamorphosis in challenging conditions like desiccation. However, not all species exhibit this ability, the yellow-bellied toad (Bombina variegata) is one such example. The underlying mechanisms behind the inability to accelerate development under desiccation remain largely unexplored. The hypothalamic-pituitary-interrenal (HPI) axis and corticosterone (CORT), which act synergistically with thyroid hormone, are thought to facilitate metamorphosis in response to desiccation stress. In this study, we aimed to investigate whether modification in the HPI axis, particularly CORT levels, contributes to the absence of adaptive plasticity in B. variegata under desiccation stress. The study design included four treatments: high water level, high water level with exogenous CORT, low water level, and low water level with metyrapone (a CORT synthesis inhibitor). The main objective was to evaluate the effects of these treatments on whole-body corticosterone levels, life history, morphological traits, and oxidative stress parameters during the prometamorphic and metamorphic climax developmental stages. While low water level had no effect on total corticosterone levels, larval period, body condition index, and metamorphic body shape, it negatively affected metamorph size, mass, and growth rate. Our findings suggest that constant exposure to desiccation stress over generations may have led to modifications in the HPI axis activity in B. variegata, resulting in adaptation to changes in water level, evident through the absence of stress response. Consequently, CORT may not be a relevant stress indicator in desiccation conditions for this species.
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Affiliation(s)
- Ana Kijanović
- Department of Evolutionary Biology, Institute for Biological Research "Siniša Stanković"-National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Tanja Vukov
- Department of Evolutionary Biology, Institute for Biological Research "Siniša Stanković"-National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Marko Mirč
- Department of Evolutionary Biology, Institute for Biological Research "Siniša Stanković"-National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Aleksandar Mitrović
- Institute for the Application of Nuclear Energy, University of Belgrade, Belgrade, Serbia
| | - Marko D Prokić
- Department of Physiology, Institute for Biological Research "Siniša Stanković"-National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Tamara G Petrović
- Department of Physiology, Institute for Biological Research "Siniša Stanković"-National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Tijana B Radovanović
- Department of Physiology, Institute for Biological Research "Siniša Stanković"-National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Branka R Gavrilović
- Department of Physiology, Institute for Biological Research "Siniša Stanković"-National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Svetlana G Despotović
- Department of Physiology, Institute for Biological Research "Siniša Stanković"-National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Jelena P Gavrić
- Department of Physiology, Institute for Biological Research "Siniša Stanković"-National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Nataša Tomašević Kolarov
- Department of Evolutionary Biology, Institute for Biological Research "Siniša Stanković"-National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
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2
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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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3
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Scaramella N, Mausbach J, Laurila A, Stednitz S, Räsänen K. Short-term responses of Rana arvalis tadpoles to pH and predator stress: adaptive divergence in behavioural and physiological plasticity? J Comp Physiol B 2022; 192:669-682. [PMID: 35857071 PMCID: PMC9388420 DOI: 10.1007/s00360-022-01449-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 04/29/2022] [Accepted: 06/24/2022] [Indexed: 11/30/2022]
Abstract
Environmental stress is a major driver of ecological and evolutionary processes in nature. To cope with stress, organisms can adjust through phenotypic plasticity and/or adapt through genetic change. Here, we compared short-term behavioural (activity) and physiological (corticosterone levels, CORT) responses of Rana arvalis tadpoles from two divergent populations (acid origin, AOP, versus neutral origin, NOP) to acid and predator stress. Tadpoles were initially reared in benign conditions at pH 7 and then exposed to a combination of two pH (acid versus neutral) and two predator cue (predator cue versus no predator cue) treatments. We assessed behavioural activity within the first 15 min, and tissue CORT within 8 and 24 h of stress exposure. Both AOP and NOP tadpoles reduced their activity in acidic pH, but the response to the predator cue differed between the populations: AOP tadpoles increased whereas NOP tadpoles decreased their activity. The AOP and NOP tadpoles differed also in their CORT responses, with AOP being more responsive (CORT levels of NOP tadpoles did not differ statistically across treatments). After 8 h exposure, AOP tadpoles had elevated CORT levels in the acid-predator cue treatment and after 24 h exposure they had elevated CORT levels in all three stress treatments (relative to the benign neutral-no-cue treatment). These results suggest that adaptation to environmental acidification in R. arvalis is mediated, in part, via behavioural and hormonal plasticity.
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Affiliation(s)
- Nicholas Scaramella
- Animal Ecology/Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden. .,Department of Ecology, Swedish University of Agricultural Sciences, Almas Alé 8, 75007, Uppsala, Sweden.
| | - Jelena Mausbach
- Department of Aquatic Ecology, Eawag, Ueberlandstrasse 133, 8600, Duebendorf, Switzerland. .,Institute of Integrative Biology, ETH Zurich, Universitätstrasse 16, 8092, Zurich, Switzerland.
| | - Anssi Laurila
- Animal Ecology/Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden
| | - Sarah Stednitz
- Department Sensory and Sensorimotor Systems, Max Planck Institute for Biological Cybernetics, Max-Planck-Ring 8, 72076, Tübingen, Germany
| | - Katja Räsänen
- Department of Aquatic Ecology, Eawag, Ueberlandstrasse 133, 8600, Duebendorf, Switzerland.,Institute of Integrative Biology, ETH Zurich, Universitätstrasse 16, 8092, Zurich, Switzerland.,Department of Biological and Environmental Science, University of Jyväskylä, Survontie 9C, 40014, Jyväskylä, Finland
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Bryant AR, Gabor CR, Swartz LK, Wagner R, Cochrane MM, Lowe WH. Differences in Corticosterone Release Rates of Larval Spring Salamanders (Gyrinophilus porphyriticus) in Response to Native Fish Presence. BIOLOGY 2022; 11:biology11040484. [PMID: 35453684 PMCID: PMC9030379 DOI: 10.3390/biology11040484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 03/11/2022] [Accepted: 03/17/2022] [Indexed: 11/16/2022]
Abstract
Simple Summary In amphibians, glucocorticoid hormones play a key role in the response to predation stress. Predators can directly affect prey via injury and death, but they can also have indirect effects due to the activity of glucocorticoids. The regulation of glucocorticoids can differ between populations that have co-evolved with predators and those that have not. We measured glucocorticoids at baseline and in response to a novel stressor in free-living larval salamanders that either live with or without fish predators naturally. We found that salamanders living with fish predators had lower measures of glucocorticoids than those without fish predators. Our study indicates that predator presence alters glucocorticoid regulation, which may allow species to better cope with native and introduced predators. Abstract Invasive fish predators are an important factor causing amphibian declines and may have direct and indirect effects on amphibian survival. For example, early non-lethal exposure to these stressors may reduce survival in later life stages, especially in biphasic species. In amphibians, the glucocorticoid hormone corticosterone is released by the hypothalamo–pituitary–interrenal axis (HPI), as an adaptive physiological response to environmental stressors. The corticosterone response (baseline and response to acute stressors) is highly flexible and context dependent, and this variation can allow individuals to alter their phenotype and behavior with environmental changes, ultimately increasing survival. We sampled larvae of the spring salamander (Gyrinophilus porphyriticus) from two streams that each contained predatory brook trout (Slavelinus fontinalis) in the lower reaches and no predatory brook trout in the upper reaches. We measured baseline and stress-induced corticosterone release rates of larvae from the lower and upper reaches using a non-invasive water-borne hormone assay. We hypothesized that corticosterone release rates would differ between larvae from fish-present reaches and larvae from fish-free reaches. We found that baseline and stressor-induced corticosterone release rates were downregulated in larvae from reaches with fish predators. These results indicate that individuals from reaches with predatory trout are responding to fish predators by downregulating corticosterone while maintaining an active HPI axis. This may allow larvae more time to grow before metamorphosing, while also allowing them to physiologically respond to novel stressors. However, prolonged downregulation of corticosterone release rates can impact growth in post-metamorphic individuals.
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Affiliation(s)
- Amanda R. Bryant
- Department of Biology, Texas State University, San Marcos, TX 78666, USA;
| | - Caitlin R. Gabor
- Department of Biology, Texas State University, San Marcos, TX 78666, USA;
- Correspondence: author:
| | | | - Ryan Wagner
- School of Environment and Natural Resources, The Ohio State University Columbus, Columbus, OH 43210, USA;
| | - Madaline M. Cochrane
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA; (M.M.C.); (W.H.L.)
| | - Winsor H. Lowe
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA; (M.M.C.); (W.H.L.)
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Grindstaff JL, Beaty LE, Ambardar M, Luttbeg B. Integrating theoretical and empirical approaches for a robust understanding of endocrine flexibility. J Exp Biol 2022; 225:274311. [PMID: 35258612 PMCID: PMC8987727 DOI: 10.1242/jeb.243408] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
There is growing interest in studying hormones beyond single 'snapshot' measurements, as recognition that individual variation in the endocrine response to environmental change may underlie many rapid, coordinated phenotypic changes. Repeated measures of hormone levels in individuals provide additional insight into individual variation in endocrine flexibility - that is, how individuals modulate hormone levels in response to the environment. The ability to quickly and appropriately modify phenotype is predicted to be favored by selection, especially in unpredictable environments. The need for repeated samples from individuals can make empirical studies of endocrine flexibility logistically challenging, but methods based in mathematical modeling can provide insights that circumvent these challenges. Our Review introduces and defines endocrine flexibility, reviews existing studies, makes suggestions for future empirical work, and recommends mathematical modeling approaches to complement empirical work and significantly advance our understanding. Mathematical modeling is not yet widely employed in endocrinology, but can be used to identify innovative areas for future research and generate novel predictions for empirical testing.
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Affiliation(s)
| | - Lynne E Beaty
- School of Science, Penn State Erie - The Behrend College, Erie, PA 16563, USA
| | - Medhavi Ambardar
- Department of Biological Sciences, Fort Hays State University, Hays, KS 67601, USA
| | - Barney Luttbeg
- Department of Integrative Biology, Oklahoma State University, OK 74078, USA
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Heterothermy as a mechanism to offset energetic costs of environmental and homeostatic perturbations. Sci Rep 2021; 11:19038. [PMID: 34561468 PMCID: PMC8463709 DOI: 10.1038/s41598-021-96828-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/05/2021] [Indexed: 11/30/2022] Open
Abstract
Environmental and biotic pressures impose homeostatic costs on all organisms. The energetic costs of maintaining high body temperatures (Tb) render endotherms sensitive to pressures that increase foraging costs. In response, some mammals become more heterothermic to conserve energy. We measured Tb in banner-tailed kangaroo rats (Dipodomys spectabilis) to test and disentangle the effects of air temperature and moonlight (a proxy for predation risk) on thermoregulatory homeostasis. We further perturbed homeostasis in some animals with chronic corticosterone (CORT) via silastic implants. Heterothermy increased across summer, consistent with the predicted effect of lunar illumination (and predation), and in the direction opposite to the predicted effect of environmental temperatures. The effect of lunar illumination was also evident within nights as animals maintained low Tb when the moon was above the horizon. The pattern was accentuated in CORT-treated animals, suggesting they adopted an even further heightened risk-avoidance strategy that might impose reduced foraging and energy intake. Still, CORT-treatment did not affect body condition over the entire study, indicating kangaroo rats offset decreases in energy intake through energy savings associated with heterothermy. Environmental conditions receive the most attention in studies of thermoregulatory homeostasis, but we demonstrated here that biotic factors can be more important and should be considered in future studies.
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7
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Combined Effects of Experimentally Elevated CORT and Predation Threat on Exploratory and Foraging Behavior of Desmognathus ochrophaeus. J HERPETOL 2021. [DOI: 10.1670/20-077] [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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8
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Denver RJ. Stress hormones mediate developmental plasticity in vertebrates with complex life cycles. Neurobiol Stress 2021; 14:100301. [PMID: 33614863 PMCID: PMC7879041 DOI: 10.1016/j.ynstr.2021.100301] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 01/04/2021] [Accepted: 01/25/2021] [Indexed: 12/24/2022] Open
Abstract
The environment experienced by developing organisms can shape the timing and character of developmental processes, generating different phenotypes from the same genotype, each with different probabilities of survival and performance as adults. Chordates have two basic modes of development, indirect and direct. Species with indirect development, which includes most fishes and amphibians, have a complex life cycle with a free-swimming larva that is typically a growth stage, followed by a metamorphosis into the adult form. Species with direct development, which is an evolutionarily derived developmental mode, develop directly from embryo to the juvenile without an intervening larval stage. Among the best studied species with complex life cycles are the amphibians, especially the anurans (frogs and toads). Amphibian tadpoles are exposed to diverse biotic and abiotic factors in their developmental habitat. They have extensive capacity for developmental plasticity, which can lead to the expression of different, adaptive morphologies as tadpoles (polyphenism), variation in the timing of and size at metamorphosis, and carry-over effects on the phenotype of the juvenile/adult. The neuroendocrine stress axis plays a pivotal role in mediating environmental effects on amphibian development. Before initiating metamorphosis, if tadpoles are exposed to predators they upregulate production of the stress hormone corticosterone (CORT), which acts directly on the tail to cause it to grow, thereby increasing escape performance. When tadpoles reach a minimum body size to initiate metamorphosis they can vary the timing of transformation in relation to growth opportunity or mortality risk in the larval habitat. They do this by modulating the production of thyroid hormone (TH), the primary inducer of metamorphosis, and CORT, which synergizes with TH to promote tissue transformation. Hypophysiotropic neurons that release the stress neurohormone corticotropin-releasing factor (CRF) are activated in response to environmental stress (e.g., pond drying, food restriction, etc.), and CRF accelerates metamorphosis by directly inducing secretion of pituitary thyrotropin and corticotropin, thereby increasing secretion of TH and CORT. Although activation of the neuroendocrine stress axis promotes immediate survival in a deteriorating larval habitat, costs may be incurred such as reduced tadpole growth and size at metamorphosis. Small size at transformation can impair performance of the adult, reducing probability of survival in the terrestrial habitat, or fecundity. Furthermore, elevations in CORT in the tadpole caused by environmental stressors cause long term, stable changes in neuroendocrine function, behavior and physiology of the adult, which can affect fitness. Comparative studies show that the roles of stress hormones in developmental plasticity are conserved across vertebrate taxa including humans.
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Affiliation(s)
- Robert J. Denver
- Department of Molecular, Cellular and Developmental Biology, and Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109-1085, USA
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9
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Cope KL, Schook MW, Benard MF. Exposure to artificial light at night during the larval stage has delayed effects on juvenile corticosterone concentration in American toads, Anaxyrus americanus. Gen Comp Endocrinol 2020; 295:113508. [PMID: 32442544 DOI: 10.1016/j.ygcen.2020.113508] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 05/02/2020] [Accepted: 05/08/2020] [Indexed: 02/02/2023]
Abstract
Artificial Light At Night (ALAN) is an environmental stressor that can disrupt individual physiology and ecological interactions. Hormones such as corticosterone are often responsible for mediating an organism's response to environmental stressors. We investigated whether ALAN was associated with a corticosterone response and whether it exacerbated the effects of another common stressor, predation. We tested for consumptive, non-consumptive, and physiological effects of ALAN and predator presence (dragonfly larvae) on a widespread amphibian, the American toad (Anaxyrus americanus). We found predators had consumptive (decreased survival) and non-consumptive (decreased growth) effects on larval toads. ALAN did not affect larval toads nor did it interact with the predator treatment to increase larval toad predation. Despite the consumptive and non-consumptive effects of predators, neither predators nor ALAN affected corticosterone concentration in the larval and metamorph life-stages. In contrast to studies in other organisms, we did not find any evidence that suggested ALAN alters predator-prey interactions between dragonfly larvae and toads. However, there was an inverse relationship between corticosterone and survival that was exacerbated by exposure to ALAN when predators were absent. Additionally, larval-stage exposure to ALAN increased corticosterone concentration in juvenile toads. Our results suggest the physiological effects of ALAN may not be demonstrated until later life-stages.
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Affiliation(s)
- Kacey L Cope
- Department of Biology, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44016, USA.
| | - Mandi W Schook
- Cleveland Metroparks Zoo, 4200 Wildlife Way, Cleveland, OH 44109, USA; Disney's Animals, Science and Environment, 1200 East Savannah Circle, Bay Lake, FL, USA.
| | - Michael F Benard
- Department of Biology, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44016, USA.
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Billig ST, Weber RN, Zimmerman LM, Wilcoxen TE. Effects of elevated corticosterone on humoral innate and antibody-mediated immunity in southern leopard frog (Lithobates sphenocephalus) tadpoles. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2020; 333:756-766. [PMID: 32798287 DOI: 10.1002/jez.2406] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 08/03/2020] [Accepted: 08/04/2020] [Indexed: 12/25/2022]
Abstract
As a free-living larval stage of a vertebrate, tadpoles are good subjects for the study of the development of physiological systems and the study of evolutionarily conserved, context-dependent responses to variable environments. While the basic components of innate and adaptive immune defenses in tadpoles are known, the impact of glucocorticoids on immune defenses in tadpoles is not well-studied. We completed four experiments to assess effects of elevation of corticosterone on humoral innate defenses and antibody-mediated immunity in southern leopard frog tadpoles (Lithobates sphenocephalus). To test humoral innate defense within the tadpoles exposed to short-term and long-term elevation of glucocorticoids, we exposed tadpoles to exogenous corticosterone for different lengths of time in each experiment (0-84 days). We used bacterial killing assays to assess humoral innate immune defense. To test antibody-mediated immune responses, we again exposed tadpoles to exogenous corticosterone, while also exposing them to Aeromonas hydrophila. We used A. hydrophila ELISA comparing IgM and IgY responses among groups. Plasma from corticosterone-dosed tadpoles killed more A. hydrophila than control tadpoles each following a short-term (14 day) and long-term (56 day) exposure to exogenous corticosterone. Conversely, corticosterone-dosed tadpoles had significantly lower IgM and IgY against A. hydrophila after 12 weeks. Our fourth experiment revealed that the lower IgY response is a product of weaker, delayed isotype switching compared with controls. These results show that elevated corticosterone has differential effects on innate and acquired immunity in larval southern leopard frogs, consistent with patterns in more derived vertebrates and in adult frogs.
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Affiliation(s)
- Samuel T Billig
- Department of Biology, Millikin University, Decatur, Illinois
| | - Rachael N Weber
- Department of Biology, Millikin University, Decatur, Illinois
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Sarma RR, Edwards RJ, Crino OL, Eyck HJF, Waters PD, Crossland MR, Shine R, Rollins LA. Do Epigenetic Changes Drive Corticosterone Responses to Alarm Cues in Larvae of an Invasive Amphibian? Integr Comp Biol 2020; 60:1481-1494. [PMID: 32544233 DOI: 10.1093/icb/icaa082] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The developmental environment can exert powerful effects on animal phenotype. Recently, epigenetic modifications have emerged as one mechanism that can modulate developmentally plastic responses to environmental variability. For example, the DNA methylation profile at promoters of hormone receptor genes can affect their expression and patterns of hormone release. Across taxonomic groups, epigenetic alterations have been linked to changes in glucocorticoid (GC) physiology. GCs are metabolic hormones that influence growth, development, transitions between life-history stages, and thus fitness. To date, relatively few studies have examined epigenetic effects on phenotypic traits in wild animals, especially in amphibians. Here, we examined the effects of exposure to predation threat (alarm cues) and experimentally manipulated DNA methylation on corticosterone (CORT) levels in tadpoles and metamorphs of the invasive cane toad (Rhinella marina). We included offspring of toads sampled from populations across the species' Australian range. In these animals, exposure to chemical cues from injured conspecifics induces shifts in developmental trajectories, putatively as an adaptive response that lessens vulnerability to predation. We exposed tadpoles to these alarm cues, and measured changes in DNA methylation and CORT levels, both of which are mechanisms that have been implicated in the control of phenotypically plastic responses in tadpoles. To test the idea that DNA methylation drives shifts in GC physiology, we also experimentally manipulated methylation levels with the drug zebularine. We found differentially methylated regions (DMRs) between control tadpoles and their full-siblings exposed to alarm cues, zebularine, or both treatments. However, the effects of these manipulations on methylation patterns were weaker than clutch (e.g., genetic, maternal, etc.) effects. CORT levels were higher in larval cane toads exposed to alarm cues and zebularine. We found little evidence of changes in DNA methylation across the GC receptor gene (NR3C1) promoter region in response to alarm cue or zebularine exposure. In both alarm cue and zebularine-exposed individuals, we found differentially methylated DNA in the suppressor of cytokine signaling 3 gene (SOCS3), which may be involved in predator avoidance behavior. In total, our data reveal that alarm cues have significant impacts on tadpole physiology, but show only weak links between DNA methylation and CORT levels. We also identify genes containing DMRs in tadpoles exposed to alarm cues and zebularine, particularly in range-edge populations, that warrant further investigation.
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Affiliation(s)
- Roshmi R Sarma
- Evolution & Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Richard J Edwards
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Ondi L Crino
- Centre for Integrative Ecology, School of Life and Environmental Sciences (LES), Deakin University, Geelong, Victoria, Australia.,Department of Biological Sciences, Macquarie University, NSW 2052, Australia
| | - Harrison J F Eyck
- Evolution & Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Paul D Waters
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Michael R Crossland
- Evolution & Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Richard Shine
- Department of Biological Sciences, Macquarie University, NSW 2052, Australia
| | - Lee A Rollins
- Evolution & Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
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Lewis JL, Sullivan AM. Salamander stress and duress: the relationship between CORT, autotomy and regeneration, and exploratory behaviour. ZOOLOGY 2020; 139:125751. [PMID: 32070799 DOI: 10.1016/j.zool.2020.125751] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 01/20/2020] [Accepted: 01/22/2020] [Indexed: 01/23/2023]
Abstract
Responses to stress are generally mediated through the production of glucocorticoids by the hypothalamic-pituitary-adrenal (or -interrenal) axis. The prolonged production of stress hormones can contribute to delayed wound healing and growth, but little is known about their influence on regeneration following tail autotomy, or exploratory behaviour in autotomized individuals. Here we examined the relationship between stress, regeneration, and exploratory behaviour in Allegheny Mountain dusky salamanders (Desmognathus ochrophaeus) by manipulating corticosterone (CORT) levels via cutaneous patch. First, we measured tail regeneration in salamanders with elevated CORT for 13 weeks after the induction of tail autotomy. Test subjects received a weekly patch to wear for one hour that was saturated with either a low CORT (0.25 mg/ml) or high CORT (0.50 mg/ml) solution. Individuals receiving CORT patches regenerated significantly less of their tail length and volume (versus control), but without exhibiting dose-dependent effects. Second, we used a factorial design to evaluate the effects of autotomy and elevated CORT on exploration within a test arena consisting of low barriers arrayed in concentric rings. Individuals experiencing tail autotomy exhibited significantly less exploratory behaviour indicated by an increased latency to cross first barrier and a decreased number of barriers crossed. Neither elevated CORT (0.50 mg/ml), nor the interaction between elevated CORT and tail autotomy significantly affected salamander activity within the array. Although CORT did not have a direct effect on explorative behaviour, a delay in regeneration attributed to CORT could lead to changes in patterns of movement in autotomized individuals.
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Affiliation(s)
- Jacquelyn L Lewis
- Department of Biology, Houghton College, Houghton, NY 14744, USA; Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
| | - Aaron M Sullivan
- Department of Biology, Houghton College, Houghton, NY 14744, USA
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13
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Florencio M, Burraco P, Rendón MÁ, Díaz-Paniagua C, Gomez-Mestre I. Opposite and synergistic physiological responses to water acidity and predator cues in spadefoot toad tadpoles. Comp Biochem Physiol A Mol Integr Physiol 2020; 242:110654. [PMID: 31926298 DOI: 10.1016/j.cbpa.2020.110654] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 12/19/2019] [Accepted: 01/06/2020] [Indexed: 12/13/2022]
Abstract
Organisms are exposed to multiple environmental factors simultaneously to which they often respond behaviorally, morphologically and/or physiologically. Amphibian larvae are quite plastic and efficiently adjust their phenotype and physiology to the reigning local conditions. Here we tested whether the combination of predator presence and low water pH induces alterations in the morphology and physiology of spadefoot toad tadpoles. We raised Pelobates cultripes tadpoles in the laboratory in water at either pH 4 or 7, and in the presence or absence of caged dragonfly nymphs, and determined their changes in shape through geometric morphometrics to assess whether predator recognition was impaired or not at low pH. We also measured levels of plasma corticosterone, activity of four antioxidant enzymes, as well as markers of oxidative damage and redox status. We found that tadpoles altered their body shape in response to predator cues even at low pH, indicating that predator recognition was not interfered by water acidity and developmental responses were robust even under abiotic stress. Water acidity was associated with increased corticosterone levels in tadpoles, whereas predator presence consistently reduced corticosterone levels. Predator presence was linked to reduced antioxidant enzyme activity, whereas the combination of both factors resulted in negative synergistic effects on lipid peroxidation and the antioxidant capacity of tadpoles. Here we show that tadpoles detect predators even at low pH but that the development of adaptive anti-predatory morphology can magnify physiological imbalances when other stressors co-occur. These results emphasize the need to understand how multiple environmental perturbations can affect animal homeostasis.
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Affiliation(s)
- Margarita Florencio
- Ecology, Evolution and Development Group, Estación Biológica de Doñana, CSIC, Seville, Spain; Dept. of Ecology, Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| | - Pablo Burraco
- Ecology, Evolution and Development Group, Estación Biológica de Doñana, CSIC, Seville, Spain; Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Miguel Ángel Rendón
- Dept. of Wetland Ecology, Estación Biológica de Doñana, CSIC, Seville, Spain
| | - Carmen Díaz-Paniagua
- Ecology, Evolution and Development Group, Estación Biológica de Doñana, CSIC, Seville, Spain
| | - Ivan Gomez-Mestre
- Ecology, Evolution and Development Group, Estación Biológica de Doñana, CSIC, Seville, Spain.
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Humphrey EA, Crespi E, Travis J. Under pressure: Short‐ and long‐term response to predation varies in two populations of a live‐bearing fish. Ethology 2019. [DOI: 10.1111/eth.12996] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Eve A. Humphrey
- Department of Biological Science Florida State University Tallahassee FL USA
| | - Erica Crespi
- School of Biological Sciences Washington State University Pullman WA USA
| | - Joseph Travis
- Department of Biological Science Florida State University Tallahassee FL USA
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15
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Narayan EJ, Forsburg ZR, Davis DR, Gabor CR. Non-invasive Methods for Measuring and Monitoring Stress Physiology in Imperiled Amphibians. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00431] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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16
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Gabor CR, Perkins HR, Heitmann AT, Forsburg ZR, Aspbury AS. Roundup™ With Corticosterone Functions as an Infodisruptor to Antipredator Response in Tadpoles. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00114] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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17
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Batabyal A, Thaker M. Social coping styles of lizards are reactive and not proactive in urban areas. Gen Comp Endocrinol 2019; 270:67-74. [PMID: 30336119 DOI: 10.1016/j.ygcen.2018.10.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 10/04/2018] [Accepted: 10/14/2018] [Indexed: 01/05/2023]
Abstract
Animals engage in social interactions with changes in their behaviour and physiology. Environmental challenges, however, can influence social interactions by adding additional stressors. Here, we investigated the effects of urbanisation on the behaviour and hormonal responses of a tropical lizard species, Psammophilus dorsalis, during social interactions. We recorded behaviour of males from suburban and rural areas during controlled encounters with other males and females. We then measured corticosterone and testosterone levels of individuals at 10 min intervals, from immediately after the social encounter to 30 min later and then at 120 min after the interaction period. We found that differences in social behaviours and subsequent hormone levels were largely driven by habitat, and not social context. Overall, we found that fewer suburban males showed behavioural displays compared to rural males during social encounters. For those that displayed, intensity of aggression was similar across populations, but courtship intensity was lower for suburban males compared to rural males. Suburban males also had significantly elevated levels of corticosterone both under control conditions (no social encounter) and following intra- and intersexual interactions, while rural males retained low levels of corticosterone across contexts. Social interactions were associated with an increase in testosterone levels in all males, but only rural males maintained elevated levels for up to 120 min after interactions with females. Thus, lizards from these suburban and rural populations showed key differences in responsiveness to and recovery from social challenges, a pattern that suggests alternative coping styles ('proactive' vs. 'reactive'). These differences in social coping styles could influence consequences of sexual selection in an urbanised world.
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Affiliation(s)
- Anuradha Batabyal
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India.
| | - Maria Thaker
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India
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Gormally BMG, Wright-Lichter J, Reed JM, Romero LM. Physiological and behavioral responses of house sparrows to repeated stressors. PeerJ 2018; 6:e4961. [PMID: 29892510 PMCID: PMC5994160 DOI: 10.7717/peerj.4961] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 05/21/2018] [Indexed: 01/02/2023] Open
Abstract
Despite decades of research, we still lack a complete understanding of what factors influence the transition of the necessary and adaptive acute stress response to what has become known as chronic stress. This gap in knowledge has illuminated the necessity for studies that examine the thresholds between these two sides of the stress response. Here, we determine how repeated exposure to acute stressors influences physiological and behavioral responses. In this repeated measures study, house sparrows (Passer domesticus) were exposed to a chronic stress protocol. We took physiological and behavioral measurements before, during, and after the protocol. Blood samples were used to assess four aspects of hypothalamic-pituitary-adrenal (HPA) axis function: baseline corticosterone, stress-induced corticosterone, negative feedback, and the maximal capacity to secrete corticosterone. We also assessed bacterial killing capacity and changes in uric acid concentration. Neophobia trials were used to assess behavioral changes throughout the protocol. We found no significant changes in HPA axis regulation in any of the four aspects we tested. However, we found that uric acid concentrations and neophobia significantly decreased after only four days of the chronic stress protocol, while bacterial killing capacity did not decrease until after eight days of exposure. These results indicate that different components of the stress response can be impacted by chronic stress on different timescales. Our results further indicate the importance of assessing multiple aspects of both physiology and behavior in order to understand how exposure to chronic stress may influence ability to cope with future challenges.
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Affiliation(s)
- Brenna M G Gormally
- Department of Biology, Tufts University, Medford, MA, United States of America
| | | | - J Michael Reed
- Department of Biology, Tufts University, Medford, MA, United States of America
| | - L Michael Romero
- Department of Biology, Tufts University, Medford, MA, United States of America
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