Dietary administration of dehydroepiandrosterone hormone influences sex differentiation of hybrid red tilapia (O. niloticus x O. mossambicus) larvae
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CitationMohamed, A. H., Traifalgar, R. F. M., Serrano Jr., A. E., Peralta, J. P., & Pedroso, F. L. (2012). Dietary administration of dehydroepiandrosterone hormone influences sex differentiation of hybrid red tilapia (O. niloticus x O. mossambicus) larvae.
PublisherAcademic Journals, New York
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Milt production of sea bass Lates calcarifer Bloch administered an analogue of luteinizing hormone-releasing hormone and 17α-methyltestosterone GV Hilomen-Garcia, RB Baldevarona & F Lacanilao -
The Israeli Journal of Aquaculture-Bamidgeh, 2002 - Society of Israeli Aquaculture and Marine BiotechnologyThe milt production responses of sexually mature sea bass Lates calcarifer to (D-Ala6, Pro9-N- ethylamide) luteinizing hormone-releasing hormone (LHRHa) and 17α-methyltestosterone injections were examined. At 24 h after injection of a low dose of LHRHa (20 μg/kg BW), the sperm count decreased significantly compared to saline-treated fish, but it returned to pre-treatment levels 48 h after injection, suggesting a possible hydration of the milt. Other milt parameters (milt volume, spermatocrit, sperm production) in LHRHa-treated fish did not vary from their controls at 24 or 48 h after injection but the overall pattern suggested a reduction in milt viscosity. Total expressible milt and spermatozoa collected over the 48-h experiment was approximately three-fold higher in LHRHa-injected fish than in saline-injected fish, indicating a stimulation of spermatozoa production, not merely milt dilution due to hydration. In a second experiment, sperm count and spermatocrit were significantly lower than those of saline-injected fish at 17 and 48 h after a single injection of a high dose of LHRHa (80 μg/kg BW). A methyltestosterone injection combined with the LHRHa injection also resulted in a significantly lower sperm count, but the spermatocrit remained comparable to the control group, suggesting a suppression of the LHRHa-induced milt hydration response. Results demonstrate that LHRHa stimulates milt hydration and spermatozoa production in milting sea bass and that a simultaneous methyltestosterone injection partially suppresses this response.
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.
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.