title: Differentiation of steroid-producing cells during ovarian differentiation in the protogynous Malabar grouper, Epinephelus malabaricus.
abstract: To understand the mechanism of sex differentiation in the protogynous Malabar grouper Epinephelus malabaricus, we performed an immunohistochemical investigation of the expression of three steroidogenic enzymes, cholesterol-side-chain-cleavage enzyme (CYP11a), aromatase (CYP19a1a), and cytochrome P45011beta-hydroxylase (CYP11b), in the gonads during ovarian differentiation. Strong positive immunoreactivity against CYP11a, the key enzyme of steroidogenesis, and CYP19a1a which is essential for estrogen (17beta-estradiol) production, appeared first in the somatic cells surrounding gonial germ cells in undifferentiated gonads and throughout ovarian differentiation. However, positive immunoreactivity against CYP11b, which is important for androgen (11-ketotestosterone) production, first appeared in the cluster of somatic cells in the ovary tunica near the dorsal blood vessel after differentiation. CYP19a1a and CYP11b did not co-localize in any cells. These results indicate that there are two types of steroid-producing cells, estrogen-producing cells and androgen-producing cells, in the gonads of this fish, and they are distributed differently, suggesting that these cells are derived from different somatic cells. Estrogen-producing cells appeared prior to ovarian differentiation, while androgen-producing cells were first detected after ovarian differentiation. These results suggest that endogenous estrogen is involved in ovarian differentiation.
authors.affiliation: Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, Okinawa, Japan. ryosuke12281985@yahoo.co.jp
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Murata
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Karimata
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Ryo
authors.initials: R
authors.lastname: Horiguchi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kishimoto
authors.forename: Motofumi
authors.initials: M
authors.lastname: Kimura
authors.forename: Tohru
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Soyano
authors.forename: Masaru
authors.initials: M
authors.lastname: Nakamura
mesh_terms: D000818:Animals; D001141:Aromatase / Q000096:biosynthesis / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism; D004958:Estradiol / Q000096:biosynthesis*; D005260:Female; D010053:Ovary / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism; D010473:Perciformes / Q000254:growth & development* / Q000378:metabolism; D012733:Sex Differentiation / Q000235:genetics; D013252:Steroid 11-beta-Hydroxylase / Q000096:biosynthesis / Q000378:metabolism; D013256:Steroids / Q000096:biosynthesis; D013739:Testosterone / Q000031:analogs & derivatives* / Q000096:biosynthesis
chemical_list: D013256:Steroids; D013739:Testosterone; D004958:Estradiol; D001141:Aromatase; D013252:Steroid 11-beta-Hydroxylase; D002786:Cholesterol Side-Chain Cleavage Enzyme; C003600:11-ketotestosterone