Expression of the Gene for CIRBP in Chelonia mydas in Relation to Sex Determination

Kristen Runge, California State University, San Marcos
Lisa Komoroske, NOAA Southwest Fisheries Science Center


The green sea turtle, Chelonia mydas, is a species of sea turtle that is not only classified as an endangered species but also, a species whose population trend is declining. In order to assess the makeup of various populations of C.mydas, sex determination is an important factor. With current methods for sex determination of sea turtles involving invasive laparoscopic procedures, researchers are evaluating less invasive means. One method being studied is the use of blood samples to analyze expression of genes linked to sex determination. Recent research in the snapping turtle, Chelydra serpentina, suggests that the gene for cold inducible RNA binding protein (CIRBP) is involved in sex determination. In this study, expression of CIRBP in C.mydas was evaluated to determine if levels of gene expression varied between male and female turtles, therefore linking CIRBP to sex determination. RNA previously extracted from whole blood samples were reverse transcribed to make complementary DNA (cDNA). The region of cDNA specific to the gene for CIRBP was then amplified via qPCR using region specific primers and probes. Relative gene expression was then calculated using delta Ct values and analyzed via comparison of average Ct values between male and female C.mydas. CIRBP expression in male C.mydas was observed to be an average Ct value of 24.40, whereas the female average Ct value was 24.97. The difference in average Ct values for CIRBP expression in male and female C.mydas was 0.77. This data suggests that there is no significant difference in expression of the gene for CIRBP in male versus female C.mydas therefore; CIRBP is not linked to sex determination.