By Ravi Palat

Faculty Mentor: Dr. Dianne Baker

Abstract

The purpose of this project was to investigate the relationship between water temperature and sex determination in the TU line of a commonly used model organism, the zebrafish (Danio rerio). While wild type zebrafish have a distinct sex determining region in their genome, the two most common lines (AB and TU) of laboratory zebrafish lack this region. Previous studies have demonstrated that temperature affects the sex ratios and expression of sex-determining genes in AB line zebrafish: warmer water temperatures result in a male skewed sex ratio and an upregulation of male promoting genes during a critical window of sex development between 15 and 30 days post fertilization (dpf). In this project, we raised two groups of TU line zebrafish at different water temperatures from 15 dpf – 30 dpf. The first group was maintained at the standard 28°C and the second at 34°C. At 30 dpf, we collected tissue samples to be used to measure relative expression of four target genes (amh, dmrt1, cyp19a1a, and bmp15) using qPCR (currently in progress). The remaining fish were reared to the adult stage, and were dissected at 86 dpf to determine their sex (according to presence of ovaries or testes) and calculate the sex ratio. The control group exhibited a male-female ratio of 5:1 while the high temperature group had a male-female ratio of 29:1.