Advances in conservation endocrinology: the application of molecular approaches to the conservation of endangered species

Abstract

Among the numerous societal benefits of comparative endocrinology is the application of our collective knowledge of hormone signaling towards the conservation of threatened and endangered species - conservation endocrinology. For several decades endocrinologists have used longitudinal hormone profiles to monitor reproductive status in a multitude of species. Knowledge of reproductive status among individuals has been used to assist in the management of captive and free-ranging populations. More recently, researchers have begun utilizing molecular and cell-based techniques to gain a more complete understanding of hormone signaling in wildlife species, and to identify potential causes of disrupted hormone signaling. In this review we examine various in vitro approaches we have used to compare estrogen receptor binding and activation by endogenous hormones and phytoestrogens in two species of rhinoceros; southern white and greater one-horned. We have found many of these techniques valuable and practical in species where access to research subjects and/or tissues is limited due to their conservation status. From cell-free, competitive binding assays to full-length receptor activation assays; each technique has strengths and weaknesses related to cost, sensitivity, complexity of the protocols, and relevance to in vivo signaling. We then present a novel approach, in which receptor activation assays are performed in primary cell lines derived from the species of interest, to minimize the artifacts of traditional heterologous expression systems. Finally, we speculate on the promise of next generation sequencing and transcriptome profiling as tools for characterizing hormone signaling in threatened and endangered species.

Keywords: Endangered species; Endocrine disruption; Hormone receptors; In vitro approaches.