title: Low concentrations of dihydrotestosterone induce female-to-male sex reversal in the frog Pelophylax nigromaculatus.
abstract: Previous studies have demonstrated that some amphibian species can be sex-reversed by high concentrations of androgens. Little attention has focused on the effects of androgenic endocrine-disrupting chemicals (EDCs) on amphibians. The present study aimed to investigate the effects of lower concentrations of the androgenic EDC 5α-dihydrotestosterone (DHT) on gonadal differentiation and development in Pelophylax nigromaculatus, a true frog distributed widely in East Asia. Tadpoles at Gosner stage 24/25 were exposed to nominal concentrations of 40 ng/L, 400 ng/L, and 4000 ng/L DHT to complete metamorphosis. In all DHT treatment groups, males and ambiguous sexes were identified based on gonadal morphology, whereas no females were found; thus, all treatment groups exhibited male-skewed ratios compared with the control group. Gonadal histological examination revealed that ambiguous sexes displayed overall testicular structure with certain ovarian characteristics, demonstrating that DHT-induced sex-ambiguous gonads were incomplete ovary-to-testis reversals (IOTTRs). The expression levels of some ovary-biased genes in the IOTTRs were significantly higher than in the control testes but lower than in the control ovaries. These results show that low concentrations of DHT induced complete or incomplete female-to-male sex reversal in P. nigromaculatus, and incomplete sex reversal retained certain ovarian characteristics not only at gonadal morphological and histological levels but also at the molecular level. They present study highlights potential risks of DHT and other androgenic EDCs for P. nigromaculatus.
authors.affiliation: College of Environment, Nanjing University of Technology, Nanjing, China.|State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing, China.
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Li
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing, China.
authors.forename: Qin-Qin
authors.initials: QQ
authors.lastname: Lou
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing, China.
authors.forename: Xiao-Ran
authors.initials: XR
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing, China.
authors.forename: Zhan-Fen
authors.initials: ZF
authors.lastname: Qin
authors.affiliation: College of Environment, Nanjing University of Technology, Nanjing, China.
authors.forename: Wu-Ji
authors.initials: WJ
authors.lastname: Wie
mesh_terms: D000818:Animals; D013196:Dihydrotestosterone / Q000494:pharmacology*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D007814:Larva / Q000187:drug effects; D008297:Male; D010053:Ovary / Q000033:anatomy & histology / Q000166:cytology / Q000187:drug effects; D011898:Ranidae / Q000254:growth & development / Q000502:physiology*; D060888:Real-Time Polymerase Chain Reaction; D019849:Sex Determination Processes / Q000187:drug effects* / Q000235:genetics; D012744:Sex Ratio; D016019:Survival Analysis; D013737:Testis / Q000033:anatomy & histology / Q000166:cytology / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D014874:Water Pollutants, Chemical; D013196:Dihydrotestosterone
keywords: Dihydrotestosterone; Endocrine-disrupting chemicals; Female-to-male sex reversal; Gonadal differentiation; Pelophylax nigromaculatus