Meeting Abstract

56-7   09:30 - 09:45  Rapid response of intron retention in Kdm6b may mediate the temperature response of testis-determining genes in the red-eared slider turtle Marroquin-Flores, R*; Bowden, R; Paitz, R; Illinois State University; Illinois State University; Illinois State University ramarro@ilstu.edu

Changes in environmental conditions, such as temperature, can impact signaling pathways critical to embryonic development in oviparous species. Many reptiles exhibit temperature-dependent sex determination (TSD), where hatchling sex is determined by incubation temperature. In the red-eared slider turtle (Trachemys scripta), a species with TSD, cool incubation temperatures induce testis development and warm temperatures induce ovary development, but we do not fully understand how embryos translate thermal cues into the genetic signal necessary for gonadal differentiation. Kdm6b is an epigenetic regulator that demethylates a histone at the promotor of the male-specific transcription factor Dmrt1 to activate its expression and trigger testis differentiation. At male-producing temperatures, Kdm6b exhibits increased expression as well as accumulation of a transcript containing an intron. We have previously shown that exposure to just 2 days of warm, female-producing temperatures results in a 10-fold reduction of intron retention (IR), suggesting that splicing responds rapidly to changes in incubation temperature. However, it is not clear how quickly Kdm6b expression recovers from exposure to warm temperatures. To test this, eggs were exposed to warm temperatures for two days before being returned to cool temperatures. Gene expression was quantified before and after heat exposure to determine how long Kdm6b expression took to return to pre-exposure levels. Consistent with prior work, we saw a drop in Kdm6b IR expression in response to heat exposure, but expression levels returned to pre-exposure levels within 2 days of the shift back to cool temperatures. These data suggest that the IR responds rapidly to changes in temperature and, with respect to Kdm6b, may enable embryos to translate changes in environmental temperature into the downstream signals necessary for testis differentiation.