PDF(Pubmed)
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.
摘要：
危险物种的激素监测对于评估个体生理状态可能是有价值的。传统的尿液和粪便非侵入性内分泌监测通常只能捕获很短的时间窗口，不能很好地反映激素的长期波动。我们在常规足部护理中检查了从非洲（Loxodontaafricana）和亚洲（Elephasmaximus）大象收集的脚趾甲修剪，以确定长期激素模式是否保留在这些缓慢生长的角化组织中。我们首先测量了大象脚趾甲的增长率，每两周一次，为期一年，建立激素沉积到指甲组织（在近端甲床）和几个月后（在指甲的远端）的脚趾甲修剪收集之间的时间延迟。在非洲大象中，脚趾甲生长约0.18±0.015毫米/天（平均值±SEM），在亚洲象中，脚趾甲增长~0.24±0.034毫米/天。这种缓慢的增长速度，再加上大象的大脚趾甲大小，可能意味着脚趾甲在甲床和甲尖之间可能包含超过一年的“激素时间表”。孕酮,睾酮和皮质醇很容易用商业酶免疫测定法检测，所有的化验都通过了验证,说明这些激素可以在大象脚趾甲提取物中准确定量。在大多数情况下,激素浓度的变化反映了成年女性和男性的预期生理模式（例如卵巢循环和芥末）以及参与动物园的个人健康记录。孕酮模式与我们对时间延迟的计算一致，与超过六个月前的女性卵巢循环一致。出乎意料的是,男性睾酮模式与样本收集时的当前芥子状态(即,而不是先前的芥子状态)一致。虽然这种样本类型需要进一步研究，这些结果表明，大象脚趾甲中保留的激素模式可以为保护者提供新的工具来帮助管理大象种群。
