Traditionally, urine, feces, and blood have been used for monitoring hormones. One of the main drawbacks of traditional samples is that they reflect short periods of hormone information. This can be problematic for species like elephants as they undergo long-term fluctuations in hormones (for example, three month long estrous cycles), which may not be as easy to detect with the day-to-day variation of traditional samples. Toenail samples attracted our interest as their slow growth may better capture fluctuations that occurred over weeks and months.
Throughout this semester, we have worked on processing toenail samples to determine their hormone concentrations. We are currently working on running samples from three African elephants (two females and a male) collected across the span of a year. My typical lab work includes pulverizing samples, doing hormone extractions, and testing hormone extracts to quantify concentrations of testosterone, progesterone and cortisol. All three hormones turned out to be highly detectable from toenail extracts and have had no issues passing verification tests. Even more exciting, variations in hormones have been preserved in our toenail samples and the variations do line up with our physiological expectations for the individual elephants (e.g., dramatic fluctuations in progesterone in a female known to be cycling, and periods of high testosterone in the male). By the end of the semester, we will have finished our data analysis of hormone concentrations with African elephants and begun work to publish the results.
I feel very fortunate to have worked on this project so far. I am interested in animal physiology and have considered possibly attending veterinary school after finishing my undergraduate degree. This project has given me the unique opportunity to work with endangered species while also giving me hands-on skills used in investigating animal physiology. In the future we plan to continue our analyses with Asian elephant toenails and will present our work at relevant conferences.