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Moss RA, Murphy KM, Gardner ST, Watkins MM, Finger JW, Kelley MD, Elsey RM, Warner DA, Mendonça MT. Exposure to ecologically relevant estrogen levels do not influence morphology or immune parameters in hatchling American alligators (Alligator mississippiensis). Comp Biochem Physiol C Toxicol Pharmacol 2024; 275:109767. [PMID: 37827394 DOI: 10.1016/j.cbpc.2023.109767] [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: 04/13/2023] [Revised: 09/26/2023] [Accepted: 10/08/2023] [Indexed: 10/14/2023]
Abstract
Human activity has increased concentrations of endocrine-disrupting contaminants (EDCs) in many ecological systems. Many EDCs are xenoestrogens, which imitate naturally derived estrogen like estradiol 17-β (E2). These pollutants can critically affect a broad range of biological functions, particularly in organisms inhabiting aquatic environments. E2 and associated receptors are involved in regulating innate immune responses, where documentation of exogenous E2 on immune parameters is important for understanding health consequences. In this study, we explore the impact of environmentally relevant concentrations of E2 on circulating glucocorticoid levels and several innate immune parameters in hatchling American alligators (Alligator mississippiensis). Twenty-three hatchling alligators were randomly placed in one of three groups that differed in dietary E2 concentration: control (no E2 exposure), low E2 (0.5 μg/kg E2), or high E2 (1 μg/kg E2) for 10 weeks. Following this period, several biomarkers were quantified to monitor the impact of E2: growth, change in body condition, white blood cell (WBC) counts, glucocorticoid levels, and general antibody response. Blood E2 concentrations were greater in individuals exposed to E2, but plasma corticosterone levels were reduced among the experimental groups. Morphology, growth, and immune parameters of E2 exposed animals did not differ from controls. These results suggest that acute exposure to increased environmental estrogen concentrations may alter plasma hormone concentrations but have little to no impact on immediate morphology or immune responses. Future studies may expand on this by monitoring biomarkers in wild populations across time, which will provide insight into how different ontogenetic stages are impacted by environmental contaminants.
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Affiliation(s)
- Regan A Moss
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, United States of America; Mailman School of Public Health, Columbia University, New York, NY 10027, United States of America
| | - Kaitlyn M Murphy
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, United States of America.
| | - Steven T Gardner
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, United States of America
| | - Madison M Watkins
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, United States of America
| | - John W Finger
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, United States of America; Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, United States of America
| | - Meghan D Kelley
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, United States of America; Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, United States of America
| | - Ruth M Elsey
- Louisiana Department of Wildlife and Fisheries, Grand Chenier, LA 70643, United States of America; 728 Saratoga Drive, Murfreesboro, TN 37130, United States of America
| | - Daniel A Warner
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, United States of America
| | - Mary T Mendonça
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, United States of America
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Murphy KM, Watkins MM, Finger JW, Kelley MD, Elsey RM, Warner DA, Mendonça MT. Xenobiotic estradiol-17ß alters gut microbiota of hatchling American alligators (Alligator mississippiensis). Environ Microbiol 2022; 24:6336-6347. [PMID: 36164972 DOI: 10.1111/1462-2920.16222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 09/23/2022] [Indexed: 01/12/2023]
Abstract
Environmental oestrogens pose serious concerns for ecosystems through their effects on organismal survival and physiology. The gut microbiome is highly vulnerable to environmental influence, yet the effects of oestrogens on gut homeostasis are unknown because they are poorly studied in wildlife populations. To determine the influence of environmental oestrogens (i.e., xenoestrogens) on the diversity and abundance of gut microbiota, we randomly assigned 23 hatchling American alligators (Alligator mississippiensis) to three ecologically relevant treatments (control, low, and high oestrogen concentrations) for 10 weeks. We predicted that xenoestrogen exposure would decrease microbial diversity and abundance within the digestive tract and that this effect would be dose-dependent. Microbial samples were collected following diet treatments and microbial diversity was determined using 16S rRNA gene-sequencing. Individuals in oestrogen-treatment groups had decreased microbial diversity, but a greater relative abundance of operational taxonomic units than those in the control group. In addition, this effect was dose-dependent; as individuals were exposed to more oestrogen, their microbiome became less diverse, less rich and less even. Findings from this study suggest that oestrogen contamination can influence wildlife populations at the internal microbial-level, which may lead to future deleterious health effects.
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Affiliation(s)
- Kaitlyn M Murphy
- Department of Biological Sciences, Auburn University, Auburn, Alabama, USA
| | - Madison M Watkins
- Department of Biological Sciences, Auburn University, Auburn, Alabama, USA
| | - John W Finger
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama, USA
| | - Meghan D Kelley
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama, USA
| | - Ruth M Elsey
- Louisiana Department of Wildlife and Fisheries, Grand Chenier, Baton Rouge, Louisiana, USA
| | - Daniel A Warner
- Department of Biological Sciences, Auburn University, Auburn, Alabama, USA
| | - Mary T Mendonça
- Department of Biological Sciences, Auburn University, Auburn, Alabama, USA
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Finger JW, Kelley MD, Zhang Y, Ka C, Hamilton MT, Elsey RM, Kavazis A, Mendonca MT. Relationships of Brain Glucocorticoid Receptors and Commonly Used Stress Parameters with Body Condition of Juvenile American Alligators (Alligator mississippiensis). SOUTH AMERICAN JOURNAL OF HERPETOLOGY 2022. [DOI: 10.2994/sajh-d-20-00008.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- John W. Finger
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
| | - Meghan D. Kelley
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
| | - Yufeng Zhang
- School of Health Studies, University of Memphis, Memphis, TN 38152, USA
| | - Cheikhouna Ka
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
| | - Matthew T. Hamilton
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907, USA
| | - Ruth M. Elsey
- Louisiana Department of Wildlife and Fisheries, Rockefeller Wildlife Refuge, Grand Chenier, LA 70643, USA
| | - Andreas Kavazis
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA
| | - Mary T. Mendonca
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
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Finger JW, Kelley M, Hamilton M, Zhang Y, Elsey R, Mendonca M, Kavazis AN. Changes in antioxidant enzyme levels following capture in juvenile American Alligators (Alligator mississippiensis) are tissue dependent. CAN J ZOOL 2022. [DOI: 10.1139/cjz-2021-0231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Many parameters used to investigate stress in vertebrates are temporally sensitive. The act of capture and sampling can influence them, hindering their functionality for evaluating the effects of stressors. Consequently, the investigation and subsequent incorporation of less time sensitive parameters are necessary to better evaluate stressors affecting vertebrates. In this study, we investigated how capture stress and handling associated with sampling influences antioxidant status in American Alligators (Alligator mississippiensis, Daudin, 1802; hereafter Alligator), long-lived, top-trophic carnivores found in the southeastern United States, by measuring levels of two antioxidant enzymes in destructive (brain and pancreas) and nondestructive (tail scutes) tissues: superoxide-dismutase-1 (SOD1) and glutathione peroxidase-1 (GPX1). Capture stress had no effect on pancreatic SOD1 and no effect on brain and pancreatic GPX1 (all p > 0.05). However, brain SOD1, scute SOD1, and scute GPX1 were all impacted by capture stress. These disparate results illustrate that the influence of capture stress on antioxidant enzymes in Alligators is tissue and marker dependent, necessitating further investigation. Our results provide a firm foundation to further investigate oxidative status in crocodilians.
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Affiliation(s)
- John W. Finger
- Auburn University, 1383, Department of Biological Sciences, Auburn, United States, 36849-5412
| | - Meghan Kelley
- Auburn University, 1383, Auburn, Alabama, United States
| | - Matthew Hamilton
- Purdue University, 311308, West Lafayette, Indiana, United States
| | - Yufeng Zhang
- The University of Memphis, 5415, Memphis, Tennessee, United States
| | - Ruth Elsey
- Departement of wildlife and fisheries, Louisiana, USA, 5476 Grand Chenier Highway, Grand Chenier, United States, 70643
| | - Mary Mendonca
- Auburn University, 1383, Auburn, Alabama, United States
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Duncan WP, Júnior JNA, Mendonça WCS, Santa Cruz IF, Samonek JF, Morais EJF, Marcon JL, Da Silveira R. Physiological stress response in free-living Amazonian caimans following experimental capture. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2022; 337:282-292. [PMID: 34905662 DOI: 10.1002/jez.2565] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 11/09/2021] [Accepted: 11/23/2021] [Indexed: 11/10/2022]
Abstract
When captured, free-living crocodilians respond by hyperstimulation of the hypothalamic-pituitary-adrenal (HPA) axis, which triggers a cascade of downstream events of physiological stress. We examined these responses in two unstressed, and stressed Amazonian caimans, Caiman crocodilus and Melanosuchus niger. Plasma corticosterone levels increased in both stressed caiman species. In M. niger, the levels of this hormone increased 5.2-fold compared with the basal range values, while in C. crocodilus this was only 1.7-fold. After stress, M. niger needed more than 6 h to return its corticosterone levels to basal range values, whereas in C. crocodilus just 0.5 h was enough. Downstream events were characterized by an increase in glucose levels, which is associated with corticosterone increments. Excessive muscle activity resulted in increased plasma lactate content in both species. Lactate levels were also related to plasma calcium concentration, possibly due to the buffering capacity for preventing lactic acidosis. Clearance of excessive lactate load was faster in M. niger (0.5 h) than in C. crocodilus (more than 6 h). Although both caiman species respond in the same way to capture, the amplitude and duration of activation of the HPA axis are different. M. niger may be potentially more sensitive to acute stress than C. crocodilus. On the other hand, C. crocodilus needs more time to recover from the lactic acid load. Our experiment provides a useful diagnostic tool for management and conservation programs, as well as evaluating the impacts of tourism and recreational capture on caimans in the Amazon.
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Affiliation(s)
- Wallice P Duncan
- Department of Morphology, Federal University of Amazonas, Manaus, Brazil
| | - Janes N A Júnior
- Graduate Program of Zoology, Federal University of Amazonas, Manaus, Brazil
| | | | | | - Jean F Samonek
- Faculty of Veterinary Medicine, Nilton Lins University, Manaus, Brazil
| | - Ester J F Morais
- Department of Biology, Federal University of Amazonas, Manaus, Brazil
| | - Jaydione L Marcon
- Graduate Program of Zoology, Federal University of Amazonas, Manaus, Brazil.,Department of Physiological Sciences, Federal University of Amazonas, Manaus, Brazil
| | - Ronis Da Silveira
- Graduate Program of Zoology, Federal University of Amazonas, Manaus, Brazil.,Department of Biology, Federal University of Amazonas, Manaus, Brazil
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Finger JW, Kelley MD, Zhang Y, Hamilton MT, Elsey RM, Mendonca MT, Kavazis A. Short-term capture stress and its effects on corticosterone levels and heat shock proteins in captive American Alligators (Alligator mississippiensis). CAN J ZOOL 2021. [DOI: 10.1139/cjz-2021-0014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Heat shock proteins (HSPs) are important mediators of the normal cellular function and the cellular stress response. As such, HSPs are often utilized to measure the effects of stressors on organisms in vivo. However, multiple variables can influence their expression, including time or season, confounding results. To investigate the utility of HSPs in measuring effects of stressors in a top-trophic carnivore, we captured 20 American Alligators (Alligator mississippiensis (Daudin, 1802)), placed them in burlap sacks for 2 h and collected blood samples over four time points (baseline, 1 and 2 h after placement into burlap sacks, and 24 h after initial capture) to measure plasma corticosterone (the main crocodilian glucocorticoid) and levels of HSP60, HSP70, and HSP90. Time point significantly affected plasma corticosterone levels in Alligators (p < 0.0001), with levels significantly elevated at 1, 2, and 24 h, relative to baseline (all p < 0.05). However, capture stress did not affect HSP60, HSP70, or HSP90 in red blood cells (all p > 0.05). Our results suggest HSPs may be important biomarkers for investigating the impacts of stressors on captive and wild crocodilians, as they are not acutely elevated by capture or handling stress.
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Affiliation(s)
- John W. Finger
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
| | - Meghan D. Kelley
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
| | - Yufeng Zhang
- College of Health Sciences, University of Memphis, Memphis, TN 38152, USA
| | - Matthew T. Hamilton
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907, USA
| | - Ruth M. Elsey
- Louisiana Department of Wildlife and Fisheries, Rockefeller Wildlife Refuge, Grand Chenier, LA 70643, USA
| | - Mary T. Mendonca
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
| | - Andreas Kavazis
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA
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Finger JW, Kelley MD, Zhang Y, Hamilton MT, Elsey RM, Mendonca MT, Kavazis AN. Antioxidant Enzymes in Destructible and Non-Destructible Tissues in American Alligators (Alligator mississippiensis). SOUTH AMERICAN JOURNAL OF HERPETOLOGY 2021. [DOI: 10.2994/sajh-d-19-00118.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- John W. Finger
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
| | - Meghan D. Kelley
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
| | - Yufeng Zhang
- School of Health Studies, University of Memphis, Memphis, TN 38152, USA
| | - Matthew T. Hamilton
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907, USA
| | - Ruth M. Elsey
- Louisiana Department of Wildlife and Fisheries, Rockefeller Wildlife Refuge, Grand Chenier, LA 70643, USA
| | - Mary T. Mendonca
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
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American Alligator (Alligator mississippiensis) Serum Inhibits Pitviper Venom Metalloproteinases. J HERPETOL 2020. [DOI: 10.1670/19-027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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