Meeting Abstract
The sex of many reptile offspring is determined by the temperature at which the eggs are incubated. Still, how thermal cues are transduced to molecular signals and then to gonadal differentiation is poorly understood in species with this temperature-dependent sex determination (TSD). Recently, researchers found that the Cold-inducible RNA-binding protein (CIRBP) encoding gene is expressed differently at male- and female-inducing temperatures in the common snapping turtle (Chelydra serpentina), which has TSD. We examined a key SNP of the CIRBP gene in painted turtle (Chrysemys picta) hatchlings to see if differences in genotypes corresponded to differences in gender, as in C. serpentina. In the first study, the turtles were derived from eggs collected from one population and then incubated at 28 °C, which on average should yield a 1:1 sex ratio in this species. We extracted DNA from liver and ran PCR using primers designed specifically for the SNP. Of the 116 samples extracted, 84 yielded a high-quality sequence for analysis. We detected no variation in the 501 bp SNP region, although we found variation at other sites along the gene. Despite the absence of within-population variation in this SNP, we further extracted DNA from C. picta from distant localities with divergent climates, and still found no notable geographic differences in this SNP. Our findings suggest that the same SNP of CIRBP does not play identical roles in TSD of C. picta and C. serpentina. Even so, the remainder of the 5437 bp CIRBP gene has yet to be sequenced and analyzed, therefore this gene may still be important in the molecular biology of TSD in C. picta.
