Transient sex change in the immature Malabar grouper, Epinephelus malabaricus, androgen treatment.
To clarify the cause of sex change recovery after the withdrawal of androgen treatment, immature female Malabar grouper were fed a diet containing 17alpha-methyltestosterone (MT) at 50 μg/g for 7 mo and then a normal diet for 6 mo. The MT brought about precocious sex change from immature ovaries to mature testes with active spermatogenesis, including the development of spermatozoa, and sex change reversed soon after MT treatment withdrawal. This result indicates that precocious sex change in immature Malabar grouper with oral MT treatment is impermanent. The expression of three steroidogenic enzymes (Cyp11a, Cyp19a1a, and Cyp11b) in the gonads of the Malabar grouper were analyzed immunohistochemically at the end of the 7-mo treatment. No apparent differences were seen in the expression pattern of these enzymes between the mature testes of MT-treated fish and the immature ovaries of control fish. In addition, serum estradiol-17beta and 11-ketotestosterone levels in treated fish were the same as those in control fish. These results indicate that in the case of immature Malabar grouper MT might have little effect on endogenous steroidogenesis during precocious sex change even though it induced active spermatogenesis in the gonads of treated fish. From these results, we also concluded that MT might have little effect on the steroidogenic endocrine pathway, and this is one cause of sex change recovery after treatment withdrawal.
Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, Sesoko, Motobu, Okinawa, Japan Shimane Aquarium, Kushiro, Hamada, Shimane, Japan ryosuke12281985@yahoo.co.jp murata@aquas.or.jp.
Ryosuke
R
Murata
Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, Sesoko, Motobu, Okinawa, Japan Ushimado Marine Laboratory, Okayama University, Kashino, Ushimado, Setouchi, Japan.
Yasuhisa
Y
Kobayashi
Okinawa Prefectural Sea Farming Center, Oohama, Motobu, Okinawa, Japan.
Hirofumi
H
Karimata
Ishigaki Branch, Okinawa Prefectural Fisheries Research and Extension Center, Kabira, Ishigaki, Okinawa, Japan.
Kazuo
K
Kishimoto
Okinawa Prefectural Sea Farming Center, Oohama, Motobu, Okinawa, Japan.
Motofumi
M
Kimura
Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, Sesoko, Motobu, Okinawa, Japan Okinawa Churashima Foundation, Ishikawa, Motobu-cho, Kunigami-gun, Okinawa, Japan.
Masaru
M
Nakamura
D000818:Animals; D001141:Aromatase / Q000378:metabolism; D001492:Bass / Q000502:physiology; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000378:metabolism; D005260:Female; D008297:Male; D008777:Methyltestosterone / Q000494:pharmacology*; D010053:Ovary / Q000187:drug effects* / Q000201:enzymology; D019849:Sex Determination Processes / Q000187:drug effects* / Q000502:physiology; D012733:Sex Differentiation / Q000187:drug effects* / Q000502:physiology; D013091:Spermatogenesis / Q000187:drug effects*; D013252:Steroid 11-beta-Hydroxylase / Q000378:metabolism; D013737:Testis / Q000187:drug effects* / Q000201:enzymology
D001141:Aromatase; D013252:Steroid 11-beta-Hydroxylase; D002786:Cholesterol Side-Chain Cleavage Enzyme; D008777:Methyltestosterone
grouper; sex change; steroidogenesis