Meeting Abstract
Despite great public and scientific interest, research into the physiology and life histories of large cetaceans presents significant obstacles due to the difficulties inherent in safely acquiring tissue samples from free-swimming animals of immense size. As an example, little is known about seasonal hormone cycles of large whales. We recently showed that steroid hormones can be extracted from baleen, keratinized tissue plates most large whales employ for feeding. Because baleen plates grow over the course of years, analysis of hormone levels along the length of the plate could give a continuous record of hormonal activity in bowhead or right whales over a decade or more. Still, many questions remained about the optimum techniques for hormone extraction from baleen and the variation in hormone deposition within a single plate. Employing bowhead baleen, we tested a suite of solutions and protocols to determine optimal conditions for efficient steroid hormone extraction (cortisol and progesterone). We then evaluated if there are substantial differences in hormone deposition across the face of the plate, that is, along putative “growth lines” representing distinct periods of growth. We found that 70% EtOH provides superior extraction in as little as two hours. Cortisol values in growth lines peaked in the central area along the test plate, typically dropping 25-50% in samples closer to edges. Progesterone showed the opposite pattern, edge higher than center, with similar 50% drops from peak value. Our results provide a flexible protocol for future steroid hormone work in baleen.
