title: Sex hormones alter sex ratios in the Indian skipper frog, Euphlyctis cyanophlyctis: Determining sensitive stages for gonadal sex reversal.
abstract: In amphibians, although genetic factors are involved in sex determination, gonadal sex differentiation can be modified by exogenous steroid hormones suggesting a possible role of sex steroids in regulating the process. We studied the effect of testosterone propionate (TP) and estradiol-17β (E2) on gonadal differentiation and sex ratio at metamorphosis in the Indian skipper frog, Euphlyctis cyanophlyctis with undifferentiated type of gonadal differentiation. A series of experiments were carried out to determine the optimum dose and sensitive stages for gonadal sex reversal. Our results clearly indicate the importance of sex hormones in controlling gonadal differentiation of E. cyanophlyctis. Treatment of tadpoles with 10, 20, 40, and 80μg/L TP throughout larval period resulted in the development of 100% males at metamorphosis at all concentrations. Similarly, treatment of tadpoles with 40μg/L TP during ovarian and testicular differentiation resulted in the development of 90% males, 10% intersexes and 100% males respectively. Treatment of tadpoles with 10, 20, 40, and 80μg/L E2 throughout larval period likewise produced 100% females at all concentrations. Furthermore, exposure to 40μg/L E2 during ovarian and testicular differentiation produced 95% females, 5% intersexes and 91% females, 9% intersexes respectively. Both TP and E2 were also effective in advancing the stages of gonadal development. Present study shows the effectiveness of both T and E2 in inducing complete sex reversal in E. cyanophlyctis. Generally, exposure to E2 increased the larval period resulting in significantly larger females than control group while the larval period of control and TP treated groups was comparable.
authors.affiliation: Department of Zoology, University of Pune, Ganeshkhind, Pune 411 007, India.
authors.forename: S K
authors.initials: SK
authors.lastname: Phuge
authors.affiliation: Department of Zoology, University of Pune, Ganeshkhind, Pune 411 007, India. Electronic address: naraharipg@unipune.ac.in.
authors.forename: N P
authors.initials: NP
authors.lastname: Gramapurohit
mesh_terms: D000818:Animals; D001001:Anura / Q000254:growth & development*; D012734:Disorders of Sex Development; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D012739:Gonadal Steroid Hormones / Q000494:pharmacology*; D006066:Gonads / Q000196:embryology*; D008297:Male; D008675:Metamorphosis, Biological / Q000187:drug effects; D012733:Sex Differentiation / Q000502:physiology; D012744:Sex Ratio
chemical_list: D012739:Gonadal Steroid Hormones; D004958:Estradiol
keywords: Estradiol-17β; Euphlyctis cyanophlyctis; Sex ratios; Sex reversal; Sex steroids; Testosterone propionate