Withdrawal of exogenous 17-alpha methyltestosterone causes reversal of sex-inversed male grouper Epinephelus suillus (Valenciennes)
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The protogynous hermaphrodite groupers Epinephelus suillus were given bi-weekly injections of 17 alpha-methyltestosterone (MT) intramuscularly for three to six months. Spermatogenesis occurred after three months of MT treatment while spermiation was observed after five to six months of MT treatment in larger fish. Neither cannulated tissue nor milt was obtained when the remaining fish were sampled four months after withdrawal of exogenous MT. However, vitellogenic eggs (size range = 0.34 to 0.56 mm) were cannulated eight months after termination of MT treatment. Presence of eggs in fish which previously had expressible or cannulated milt indicates that the sex-inversed male E. suillus reverted back to the female condition upon withdrawal of exogenous MT. This information is useful in the line production of functional males which is the limiting factor in induced breeding of groupers.
CitationTan-Fermin, J. D. (1992). Withdrawal of exogenous 17-alpha methyltestosterone causes reversal of sex-inversed male grouper Epinephelus suillus (Valenciennes).
PublisherSan Carlos Publications
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Dietary administration of dehydroepiandrosterone hormone influences sex differentiation of hybrid red tilapia (O. niloticus x O. mossambicus) larvae AH Mohamed, RFM Traifalgar, AE Serrano Jr., JP Peralta & FL Pedroso -
Journal of Fisheries and Aquatic Science, 2012 - Academic Journals, New YorkEffects of a steroid hormone Dehydroepiandrosterone (DHEA) on sex differentiation of hybrid red Tilapia Oreochromis niloticus x O. mossambicus larvae were investigated. Three day-old tilapia larvae were fed diets supplemented with varying concentrations of DHEA (0, 20, 40, 80 and 160 mg kg-1 feed) for 24 days. A positive control group fed with diet containing 60 mg kg-1 of 17α-methyl testosterone was also included in the experimental run. Results indicate that among the DHEA treatment groups, larvae fed with 160 mg kg-1 DHEA showed the highest percentage of males that is comparable to the number of differentiated male fish observed in treatment group receiving the 17α-methyl testosterone as the positive control group. DHEA supplementation also improves weight gain and enhances feed conversion ratio. These findings suggest that DHEA can be used as a dietary supplement to induce masculinization and can improve the growth performance of tilapia larvae.
ArticleGF Quinitio, JD Tan-Fermin & A Nagai -
Fisheries Science, 2001 - Japanese Society of Fisheries ScienceThirty 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.
Induction of sex inversion in juvenile grouper, Epinephelus suillus, (Valenciennes) by injections of 17α-Methyltestosterone JD Tan-Fermin, LMB Garcia & AR Castillo Jr. -
Bulletin of Environmental Contamination and Toxicology, 1994 - The Ichthyological Society of JapanFour 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.