Embryonic Development of Progesterone Receptors of Female Green Turtles (Chelonia Mydas)
Progesterone is a steroid hormone secreted by the corpus luteum during embryogenesis. Progesterone and its
receptors is well studied in female reproductive organs. However, less research was done in reptiles, such as green sea
turtles, Chelonia mydas. In none mammalian systems, progesterone facilitates expression of several egg-white proteins some
of which are involved in embryogenesis through the expression of progesterone receptors (PR) of various tissues of
reproductive organs, kidneys, liver, spleen and intestines. Certain temperatures determine sex differentiation of green turtles.
For example, at 30 oC, 100% of embryos are formed, while males are formed at higher temperature. This is known as
thermos sensitive period (TSP). Expression of PRs in green turtle female embryos is not well established. In this study,
freshly laid eggs were collected at random from Ras Al-Hadd, Oman, which is one of the largest nesting beaches of this
species in the world. The eggs were incubated at 30 oC and embryo tissues were collected during various stages of
development. Embryonic proteins were extracted, separated by SDS-PAGE and PRs were detected by ELISA and Western
blot techniques. It was found that PR expression occurs after 3-4 weeks and was stable during the TSP with minor increase
after this period. These findings suggest the endocrinological role of this receptor in sex determination during
embryogenesis. The study provides valuable knowledge to understand sex determination and hatching success to establish
conservation strategies of this endangered species.
Keywords- Progesterone Receptors, embryogenesis, Green turtles, Proteins, blot techniques