23 Anti-Müllerian hormone in polar bears (Ursus maritimus): assay validation and concentrations in relation to sex, age, and season
A. Tompros A B , J. Wojtusik B , M. Philpott B , T. L. Roth B , M. Campbell B and E. Curry BA Center for Wildlife Health, Department of Forestry, Wildlife, and Fisheries, University of Tennessee Institute of Agriculture, Knoxville, TN, USA
B Center for Conservation and Research of Endangered Wildlife (CREW), Cincinnati Zoo & Botanical Garden, Cincinnati, OH, USA
Reproduction, Fertility and Development 34(2) 245-246 https://doi.org/10.1071/RDv34n2Ab23
Published: 7 December 2021
© 2022 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the IETS
Decreased availability of sea ice, environmental pollutants, and other anthropogenic factors may be impacting the reproductive success of wild polar bears. Improved methods for monitoring reproduction and fertility of in situ populations are needed; however, many hormones have yet to be characterised in this species. Anti-Müllerian hormone (AMH) is commonly used as a biomarker for fertility and ovarian reserve in humans and some domestic species but has not been analysed in any bear species. The study’s objectives were to validate a commercial ELISA to quantify AMH in polar bear serum and determine differences in AMH concentrations in relation to sex, age, and season. The AMH Gen II ELISA (Beckman Coulter) was validated by demonstrating parallelism between the assay’s standard curve and serial dilutions of pooled polar bear serum (neat, 1:2 to 1:64). Fifty-one archived serum samples (24 samples from eight females, 27 samples from 14 males) collected from zoo bears were analysed according to the manufacturer’s instructions. Samples were evaluated by sex (male, female), age class (immature: ≤6.05 years; young adult: 6.1–12.05 years; adult: 12.1–20.05 years; senior: ≥20.1 years) and reproductive season (breeding: January–May; nonbreeding: June–December). Statistical analysis included a vector generalised linear model with Tobit distribution for female samples and a linear-mixed effects model with individual as the random effect for male samples. All analyses were performed in R (version 3.6.2; Genstat) using package “VGAM” for female samples and package “stats” for male samples. Results are presented in nanograms of AMH per milliliter (ng mL−1) of serum ± standard error of the mean. Sixteen samples (11 female, 5 male) were below the assay’s analytical sensitivity (0.078 ng mL−1) and were assigned this value as their concentration for analysis. AMH concentrations were higher (P < 0.01) in males (15.89 ± 2.03) than in females (0.25 ± 0.05), with males experiencing higher concentrations during the nonbreeding season (P < 0.01; 20.95 ± 6.32) than the breeding season (8.59 ± 2.54). AMH concentrations also tended to decrease as age increased for females (P = 0.069) and males (P = 0.23). Results of this study showed that AMH is detectable in polar bear serum and that concentrations differ by sex, age, and season. These findings warrant further characterisation of AMH and its potential for assessing the fertility of this species.
This project was made possible by the Charlotte R. Schmidlapp Fund.
