Department of Biological Sciences, Northern Arizona University, 617 S. Beaver St., 86011 Flagstaff, AZ, USA.
Smithsonian-Mason School of Conservation & Department of Biology, George Mason University, 1500 Remount Rd, Front Royal, VA 22630, USA.
Gen Comp Endocrinol. 2022 Sep 1;325:114053. doi: 10.1016/j.ygcen.2022.114053. Epub 2022 May 14.
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.
短吻针鼹（Tachyglossus aculeatus）是一种仅分布于澳大利亚和新几内亚的单孔目动物，也是澳大利亚分布最广的本土哺乳动物。尽管数量众多，但我们对针鼹的生活史仍有许多不了解，例如两性的繁殖周期、应激生理学模式以及代谢可能随季节变化。在其他野生动物中，通过分析在这些组织生长过程中沉积的类固醇和甲状腺激素的纵向模式，使用由角蛋白（毛发、爪子等）组成的生长缓慢的表皮样本类型来评估这些问题。毛发和刺构成了针鼹的皮毛，刺是与毛发同源的角蛋白化结构。因此，针鼹刺可能是一种可行的激素分析样本类型，可以更好地了解针鼹的生物学特性。这项工作的目的是确定类固醇激素是否可在针鼹刺中检测到，进行测定验证，并建立使用市售试剂盒从针鼹刺中提取和定量激素的方案。我们还使用光和电子显微镜检查了横截面的刺，以寻找任何可能表明刺生长速度的年度生长标记的证据。皮质酮、孕酮、雌二醇和睾酮在所有样本中均可检测到，并且针鼹刺提取物通过了标准测定验证（平行性和准确性），这表明市售的试剂盒可以准确地定量这种样本类型中的激素。在刺中没有发现可见的生长标记，因此目前尚不清楚刺的生长速度。针鼹刺有望成为一种新型基质，可从中定量激素；下一步应该确定刺的年生长率、生长率可能随季节的变化以及刺随时间的持久性，以便进行生理验证，即生理状态与刺中激素浓度之间的关系。
