title: Sexual Fate Reprogramming in the Steroid-Induced Bi-Directional Sex Change in the Protogynous Orange-Spotted Grouper, Epinephelus coioides.
abstract: Androgen administration has been widely used for masculinization in fish. The mechanism of the sex change in sexual fate regulation is not clear. Oral administration or pellet implantation was applied. We orally applied an aromatase inhibitor (AI, to decrease estrogen levels) and 17α-methyltestosterone (MT, to increase androgen levels) to induce masculinization to clarify the mechanism of the sex change in the protogynous orange-spotted grouper. After 3 mo of AI/MT administration, male characteristics were observed in the female-to-male sex change fish. These male characteristics included increased plasma 11-ketotestosterone (11-KT), decreased estradiol (E2) levels, increased male-related gene (dmrt1, sox9, and cyp11b2) expression, and decreased female-related gene (figla, foxl2, and cyp19a1a) expression. However, the reduced male characteristics and male-to-female sex change occurred after AI/MT-termination in the AI- and MT-induced maleness. Furthermore, the MT-induced oocyte-depleted follicle cells (from MT-implantation) had increased proliferating activity, and the sexual fate in a portion of female gonadal soma cells was altered to male function during the female-to-male sex change. In contrast, the gonadal soma cells were not proliferative during the early process of the male-to-female sex change. Additionally, the male gonadal soma cells did not alter to female function during the male-to-female sex change in the AI/MT-terminated fish. After MT termination in the male-to-female sex-changed fish, the differentiated male germ cells showed increased proliferating activities together with dormancy and did not show characteristics of both sexes in the early germ cells. In conclusion, these findings indicate for the first time in a single species that the mechanism involved in the replacement of soma cells is different between the female-to-male and male-to-female sex change processes in grouper. These results also demonstrate that sexual fate determination (secondary sex determination) is regulated by endogenous sex steroid levels.
authors.affiliation: Department of Aquaculture, National Taiwan Ocean University, Keelung 20224, Taiwan.|Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung 20224, Taiwan.
authors.forename: Guan-Chung
authors.initials: GC
authors.lastname: Wu
authors.affiliation: Department of Aquaculture, National Taiwan Ocean University, Keelung 20224, Taiwan.
authors.forename: Wei-Guan
authors.initials: WG
authors.lastname: Tey
authors.affiliation: Department of Aquaculture, National Taiwan Ocean University, Keelung 20224, Taiwan.
authors.forename: Hau-Wen
authors.initials: HW
authors.lastname: Li
authors.affiliation: Department of Aquaculture, National Taiwan Ocean University, Keelung 20224, Taiwan.|Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung 20224, Taiwan.
authors.forename: Ching-Fong
authors.initials: CF
authors.lastname: Chang
mesh_terms: D000284:Administration, Oral; D000818:Animals; D047072:Aromatase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D001492:Bass / Q000097:blood / Q000502:physiology*; D049109:Cell Proliferation / Q000187:drug effects; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D012739:Gonadal Steroid Hormones / Q000097:blood; D008297:Male; D008777:Methyltestosterone / Q000008:administration & dosage / Q000494:pharmacology*; D010063:Ovum / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D019849:Sex Determination Processes / Q000187:drug effects*; D013094:Spermatozoa / Q000166:cytology / Q000187:drug effects / Q000502:physiology
chemical_list: D047072:Aromatase Inhibitors; D012739:Gonadal Steroid Hormones; D008777:Methyltestosterone