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Rich G, Stennett R, Galloway M, McClure M, Riley R, Freeman EW, Hunt KE. Nailing it: Investigation of elephant toenails for retrospective analysis of adrenal and reproductive hormones. CONSERVATION PHYSIOLOGY 2024; 12:coae048. [PMID: 39100510 PMCID: PMC11295213 DOI: 10.1093/conphys/coae048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 06/25/2024] [Accepted: 07/15/2024] [Indexed: 08/06/2024]
Abstract
Hormone monitoring of at-risk species can be valuable for evaluation of individual physiological status. Traditional non-invasive endocrine monitoring from urine and faeces typically captures only a short window in time, poorly reflecting long-term hormone fluctuations. We examined toenail trimmings collected from African (Loxodonta africana) and Asian (Elephas maximus) elephants during routine foot care, to determine if long-term hormone patterns are preserved in these slow-growing keratinized tissues. We first measured the growth rate of elephant toenails biweekly for one year, to establish the temporal delay between deposition of hormones into nail tissue (at the proximal nail bed) and collection of toenail trimmings months later (at the distal tip of the nail). In African elephants, toenails grew ~0.18 ± 0.015 mm/day (mean ± SEM) and in Asian elephants, toenails grew ~0.24 ± 0.034 mm/day. This slow growth rate, combined with the large toenail size of elephants, may mean that toenails could contain a 'hormone timeline' of over a year between the nail bed and nail tip. Progesterone, testosterone and cortisol were readily detectable using commercial enzyme immunoassays, and all assays passed validations, indicating that these hormones can be accurately quantified in elephant toenail extract. In most cases, variations in hormone concentrations reflected expected physiological patterns for adult females and males (e.g. ovarian cycling and musth) and matched individual health records from participating zoos. Progesterone patterns aligned with our calculations of temporal delay, aligning with female ovarian cycling from over six months prior. Unexpectedly, male testosterone patterns aligned with current musth status at the time of sample collection (i.e. rather than prior musth status). Though this sample type will require further study, these results indicate that preserved hormone patterns in elephant toenails could give conservationists a new tool to aid management of elephant populations.
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Affiliation(s)
- Garrett Rich
- Department of Biology, George Mason University, 4400 University Drive, Fairfax, VA 22030, USA
| | - Rebecca Stennett
- The Maryland Zoo in Baltimore, 1 Safari Place Baltimore, MD 21217, USA
| | - Marie Galloway
- Smithsonian’s National Zoo and Conservation Biology Institute, 3001 Connecticut Ave NW, Washington, DC 20008, USA
| | - Mike McClure
- The Maryland Zoo in Baltimore, 1 Safari Place Baltimore, MD 21217, USA
| | - Rebecca Riley
- Smithsonian’s National Zoo and Conservation Biology Institute, 3001 Connecticut Ave NW, Washington, DC 20008, USA
| | - Elizabeth W Freeman
- School of Integrative Studies, George Mason University, 4400 University Drive, Fairfax, VA 22030, USA
| | - Kathleen E Hunt
- Department of Biology, George Mason University, 4400 University Drive, Fairfax, VA 22030, USA
- Smithsonian-Mason School of Conservation, 1500 Remount Road, Front Royal, VA 22630, USA
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Cherney MD, Fisher DC, Auchus RJ, Rountrey AN, Selcer P, Shirley EA, Beld SG, Buigues B, Mol D, Boeskorov GG, Vartanyan SL, Tikhonov AN. Testosterone histories from tusks reveal woolly mammoth musth episodes. Nature 2023; 617:533-539. [PMID: 37138076 DOI: 10.1038/s41586-023-06020-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 03/27/2023] [Indexed: 05/05/2023]
Abstract
Hormones in biological media reveal endocrine activity related to development, reproduction, disease and stress on different timescales1. Serum provides immediate circulating concentrations2, whereas various tissues record steroid hormones accumulated over time3,4. Hormones have been studied in keratin, bones and teeth in modern5-8 and ancient contexts9-12; however, the biological significance of such records is subject to ongoing debate10,13-16, and the utility of tooth-associated hormones has not previously been demonstrated. Here we use liquid chromatography with tandem mass spectrometry paired with fine-scale serial sampling to measure steroid hormone concentrations in modern and fossil tusk dentin. An adult male African elephant (Loxodonta africana) tusk shows periodic increases in testosterone that reveal episodes of musth17-19, an annually recurring period of behavioural and physiological changes that enhance mating success20-23. Parallel assessments of a male woolly mammoth (Mammuthus primigenius) tusk show that mammoths also experienced musth. These results set the stage for wide-ranging studies using steroids preserved in dentin to investigate development, reproduction and stress in modern and extinct mammals. Because dentin grows by apposition, resists degradation, and often contains growth lines, teeth have advantages over other tissues that are used as records of endocrine data. Given the low mass of dentin powder required for analytical precision, we anticipate dentin-hormone studies to extend to smaller animals. Thus, in addition to broad applications in zoology and palaeontology, tooth hormone records could support medical, forensic, veterinary and archaeological studies.
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Affiliation(s)
- Michael D Cherney
- Museum of Paleontology, University of Michigan, Ann Arbor, MI, USA.
- Medical School, University of Michigan, Ann Arbor, MI, USA.
| | - Daniel C Fisher
- Museum of Paleontology, University of Michigan, Ann Arbor, MI, USA
- Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA
| | | | - Adam N Rountrey
- Museum of Paleontology, University of Michigan, Ann Arbor, MI, USA
| | - Perrin Selcer
- Program in the Environment, University of Michigan, Ann Arbor, MI, USA
| | - Ethan A Shirley
- Museum of Paleontology, University of Michigan, Ann Arbor, MI, USA
- Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA
| | - Scott G Beld
- Museum of Paleontology, University of Michigan, Ann Arbor, MI, USA
| | | | - Dick Mol
- Natural History Museum, Rotterdam, Netherlands
| | - Gennady G Boeskorov
- Diamond and Precious Metals Geology Institute, Siberian Branch of the Russian Academy of Sciences, St Jean de Luz, Russian Federation
| | - Sergey L Vartanyan
- Laboratory of Cenozoic Geology and Paleogeography, North-east Interdisciplinary Scientific Research Institute, Far-East Branch, Russian Academy of Sciences, Magadan, Russian Federation
| | - Alexei N Tikhonov
- Laboratory of Mammals, Zoological Institute of the Russian Academy of Sciences, St Petersburg, Russian Federation
- Mammoth Museum, North-Eastern Federal University, Yakutsk, Russian Federation
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Application of Felid Hair for Non-Invasive Tracking of Animal Reproductive Status and Adrenal Activity. Animals (Basel) 2022; 12:ani12202792. [PMID: 36290178 PMCID: PMC9597714 DOI: 10.3390/ani12202792] [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: 07/20/2022] [Revised: 10/11/2022] [Accepted: 10/12/2022] [Indexed: 11/05/2022] Open
Abstract
Hair can be a useful matrix to examine the hormonal status of an animal, although it is difficult to correlate the results to a specific time point. The aim of this study was to evaluate seasonal changes in cortisol and testosterone levels in the hair of four feline species (lynx, Lynx lynx, n = 8; Amur wildcat, Prionailurus bengalensis euptilurus, n = 8; caracal, Caracal caracal, n = 6 and domestic cat, Felis catus, n = 17) with different breeding strategies. Animals of both sexes were sampled over the year, once per season (every three months), and the concentrations of hair testosterone and cortisol were measured by EIA. Both hormones showed annual dynamic changes, which coincided with the reproductive seasonality of the studied species. Sexual differences in testosterone level were found only during the mating season (spring for lynx and Amur wildcats, spring-summer for domestic cats), when testosterone levels were higher in males than in females. Cortisol levels were higher in males than in females in domestic cats and Amur wildcat, but also only during the mating season. Seasonal increases in testosterone were observed in three seasonal breeders (lynx, Amur wildcat and domestic cat) but not in caracal, which had high testosterone levels over the whole year. In lynx and Amur wildcat, it decreased sharply in the summer. Cortisol levels increased during the mating period in domestic cat males and lynx of both sexes; in caracal, an increase in cortisol was related to the transfer of animals to smaller winter cages. Measurements of steroids in hair can provide a reliable method for evaluating the reproductive status and the activity of the hypothalamus-pituitary-adrenal axis in several felid species.
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Fabio Braga A, E Hunt K, Dillon D, Minicozzi M, C Nicol S, Buck CL. Can spines tell a story? Investigation of echidna spines as a novel sample type for hormone analysis in monotremes. Gen Comp Endocrinol 2022; 325:114053. [PMID: 35580688 DOI: 10.1016/j.ygcen.2022.114053] [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: 08/14/2021] [Revised: 05/11/2022] [Accepted: 05/12/2022] [Indexed: 11/04/2022]
Abstract
The short-beaked echidna (Tachyglossus aculeatus) is a monotreme endemic to Australia and New Guinea, and is the most widespread native mammal in Australia. Despite its abundance, there are considerable gaps in our understanding of echidna life history such as reproductive cycles in both sexes, patterns of stress physiology, and possible seasonal changes in metabolism. Slow-growing integumentary sample types comprised of keratin (hair, claw, etc.) have been used in other wildlife to assess these questions via analysis of longitudinal patterns in steroid and thyroid hormones that are deposited in these tissues as they grow. Hairs and spines comprise the pelage of echidnas, the spines being keratinized structures homologous to hair. Thus, echidna spines could be a viable sample type for hormone analysis contributing to a better understanding of the biology of echidnas. The aim of this work was to determine whether steroid hormones are detectable in echidna spines, to perform assay validations, and to establish a protocol for extracting and quantifying hormones in echidna spines using commercially available assay kits. We also inspected cross-sectioned spines using light and electron microscopy for any evidence of annual growth markers that might enable inferences about spine growth rate. Corticosterone, progesterone, estradiol, and testosterone were detectable in all samples, and echidna spine extract passed standard assay validations (parallelism and accuracy), indicating that commercially available assay kits can quantify hormones accurately in this sample type. No visible growth marks were identified in the spines and thus spine growth rate is currently unknown. Echidna spines show promise as a novel matrix from which hormones can be quantified; next steps should involve determination of spine annual growth rate, possible seasonal changes in growth rate, and persistence of spines over time in order to perform physiological validations, i.e., relationship between physiological status and hormone concentrations in spines.
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Affiliation(s)
- Ana Fabio Braga
- Department of Biological Sciences, Northern Arizona University, 617 S. Beaver St., 86011 Flagstaff, AZ, USA.
| | - Kathleen E Hunt
- Smithsonian-Mason School of Conservation & Department of Biology, George Mason University, 1500 Remount Rd, Front Royal, VA 22630, USA
| | - Danielle Dillon
- Department of Biological Sciences, Northern Arizona University, 617 S. Beaver St., 86011 Flagstaff, AZ, USA
| | - Michael Minicozzi
- Department of Biological Sciences, Northern Arizona University, 617 S. Beaver St., 86011 Flagstaff, AZ, USA
| | - Stewart C Nicol
- School of Natural Sciences, University of Tasmania, Hobart, Tasmania, Australia
| | - C Loren Buck
- Department of Biological Sciences, Northern Arizona University, 617 S. Beaver St., 86011 Flagstaff, AZ, USA
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