Induction of sex inversion in juvenile grouper, Epinephelus malabaricus, (Bloch and Schneider) by bi-weekly injections of 17 alpha-methyltestosterone
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1989Author
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Abstract
Groupers (Family Serranidae) are protogynous hermaphrodites. Natural sex inversion of different species occurs at 2-11 years of age . The scarcity of wild mature males and the length of time to change sex underline the need to do induced sex inversion studies. In Epinephelus tauvina and E. fario, sex inversion was successfully induced by oral administration of 17 alpha-methyltestosterone (MT). This paper reports on the induction of sex inversion of juvenile grouper E. malabaricus using bi-weekly intramuscular injections of MT.
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Tan-Fermin, J. D., Garcia, L. M. B., & Castillo Jr., A. R. (1989). Induction of sex inversion in juvenile grouper, Epinephelus malabaricus, (Bloch and Schneider) by bi-weekly injections of 17 alpha-methyltestosterone. In D. K. O. Chan (Ed.), Hormones and the Environment. Proceedings of an International Symposium held at University of Hong Kong, 18-20 December 1989 (pp. 19–20). Hong Kong: Society for the Study of Endocrinology, Metabolism and Reproduction, University of Hong Kong.
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Induction of sex inversion in juvenile grouper, Epinephelus suillus, (Valenciennes) by injections of 17α-Methyltestosterone
; Garcia, Luis Maria
; (The Ichthyological Society of Japan, 1994)
Four groups of two-year old juvenile groupers (Epinephelus suillus), each with 8-9 individuals of mean body weight (BW) 1.2 kg, were treated with 17α-methyltestosterone (MT). MT was injected intramuscularly within the range of 0.5-5.0 mg kg-1 BW every 15 days. Gonadal biopsy and stripping of the abdomen was done every 15 days, the fish being sacrificed after six or twelve injections. Initial controls had immature ovaries containing primary oocytes in lamellae that extended into the central lumen. After six injections, proliferation of stromal and gonial cells were observed in all fish sampled. Regardless of treatment, gonad sections of fish with a minimum BW of 1.2 kg showed degeneration of primary oocytes and the presence of spermatogenic cells. Milt was also present in larger-sized fish (BW: 1.5 kg) given 0, 0.5 and 1.0mg MTkg-1 BW, after such fish had received an accumulated dose of 5 or 12mg MTkg-1 BW. However, gonad sections of smaller-sized fish following these treatments contained only primary oocytes and gonial cells after six (BW: 0.7-1.0kg) or twelve (BW: 0.6-1.3 kg) injections. In contrast, all fish treated with 5 mg MT kg-1 BW had testes in active spermatogenesis after six (BW: 1.2-1.6 kg) or twelve (BW: 0.8 kg) injections. Gonad weight and gonadosomatic index values decreased during consecutive sampling. Induction of female-to-male sex inversion in juvenile E. suillus by MT was probably synergistic with age and size. -
Possible application of mibolerone for induced sex inversion of grouper Epinephelus coioides
(Japanese Society of Fisheries Science, 2001)Thirty immature juvenile grouper Epinephelus coioides (19-168 g bodyweight, BW) were randomly stocked in four units 6 t tanks to determine if mibolerone can be used to induce sex inversion in groupers. After acclimatization and weaning to artificial feed, the feed given daily (4% BW/day) was supplemented with 0, 50, 100, and 200 μg mibolerone/kg feed for about 18 weeks. Thereafter, the hormone treatment was withdrawn and the experiment was terminated at Week 24. Ten fish were killed for gonad histology at stocking to serve as an initial control while about three to five fish were killed every 8 weeks. In general, ovaries of initial controls showed the presence of moderate stromal cells and gonia and few primary oocytes. At Weeks 8 and 16, ovaries of the control fish (0 μg/kg) were similar to that of the initial control except that primary oocytes increased at Week 24. Gonads of fish fed diets containing 100 and 200 μg/kg had none to moderate spermatocytes and few spermatids at Week 8 and 16, although spermatozoa were not observed, indicating that the fish were undergoing spermatogenesis. Spermatogenesis at 50 μg/kg was not as advanced since only few spermatocytes occurred at Weeks 8 followed by moderate gonia and no spermatocytes and spermatids at Week 16. However, the presence of few primary oocytes was observed when mibolerone was withdrawn suggesting that sex-inversed fish reverted back to a female condition. These results show that sex inversion in juvenile grouper can be induced by oral administration of mibolerone and may have possible application on mature females to produce functional males. -
Gonadal response of juvenile protogynous grouper (Epinephelus fuscoguttatus) to long term recombinant follicle-stimulating hormone administration
Palma, Peter; ; ; ; ; ; (Oxford University Press, 2019-03)
The role of follicle stimulating hormone (FSH) in the gonadal development of protogynous hermaphroditic grouper (E. fuscoguttatus) was investigated. Recombinant giant grouper (E. lanceolatus) FSH (rggFSH) was produced in yeast. Its receptor binding capacity and steroidogenic potency were confirmed in vitro. Weekly injections of rggFSH to juvenile tiger grouper for 8 weeks (100 μg/kg body weight, BW) resulted in significantly larger and more advanced oocytes (cortical alveolar stage vs. primary growth stage in control). Sustained treatment with rggFSH (20 to 38 weeks at 200 μg/kg BW) resulted in significant reduction in gonad size, degeneration of oocytes and proliferation of spermatogonial cells, indicative of female to male sex change. Gene expression analysis showed that, while initiating female to male sex change, the rggFSH significantly suppressed the steroidogenic genes cyp11b, cyp19a1a and foxl2 which restrained the endogenous production of sex steroid hormones thus prevented the differentiation of spermatogonial cells. Expression profile of sex markers dmrt1, amh, figla and bmp15 suggests that the observed sex change was restricted at the initiation stage. Based on these results, we propose that the process of female to male sex change in the protogynous grouper is initiated by FSH, rather than sex steroids and likely involves steroid-independent pathway. The cortical alveolar stage in oocyte development is the critical point after which FSH-induced sex change is possible in grouper.
