• Journal of Aquaculture
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• v.8 no.2
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• pp.77-83
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• 1995

The effects of six levels (0, 5, 10, 15, 20, and 25 ppm) of dietary $17\alpha-Methyltestosterone$ (MT) on sex reversal and growth of Oreochromis aureus (Steindachner) and O. niloticus (L.) were evaluated. Fifteen ppm MT produced $100\%$ male populations in both species. Both MT-treated and untreated O. niloticus grew significantly faster than their O. aureus counterparts (P<0.05).

• Journal of Aquaculture
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• v.11 no.2
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• pp.173-182
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• 1998

The study has been conducted to understand gonadal development and the effects of $17^{\alpha}$-methyltestosterone on sex inversion of the red spotted grouper, Epinephelus akaara. Fish were collected from Deukyand bay in the southern coast of Korea in August, 1996 and then they had been cultivated at the indoor tank until August, 1997. Gonad somatic index (GSI) in the females of both treated and control group began to increase from February when water temperature was rainse again, and reached the maximum value in August, whereas it had decreased from September adn thereafter maintained relatively low value until January. Unlike females, GSI in the male or intersex of treated groups decreased after June. Hepatosomatic index (HSI) of the control group tended to show the relatively low around Autumn, whereas it showed relatively highr value in April and June when the ovary was in the growing stage. Although the treated groups showed relatively higher value of the HSI than the control, hte paterns in monthly variation of HSI were similar to the control. Sexual change of the female grouper to the male was attempted by acceleration with oral administration of $17^{\alpha}$-methyltestosterone at the dose of 0.2 and 0.5mg/kg fish for 120days. Transitional hermaphroditic gonads were observed from the various size of groupers ranging 21.0 to 36.1 cm in total length, while the functional males could be induced from th individuals of 28.8 to 33.5cm in total length. This result indicated that larger groupers than 30cm in total length should be used for sex inversion to maleness with $17^{\alpha}$-methyltestosterone.

• Development and Reproduction
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• v.17 no.2
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• pp.79-85
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• 2013

To understand the sex reversal characteristics in the longtooth grouper (Epinephelus bruneus), this study examined the sex reversal and artificial masculinization of wild caught E. bruneus reared in indoor rearing tank after a 17${\alpha}$-methyltestosterone injection. To domesticate a broodstock, 64 wild caught E. bruneus, between 47.0 to 110.0 cm in total length and from 1.5 to 21.4 kg in body weight, were reared in indoor rearing tank (4.0 to 5.0 m wide, and 2.5 to 3.0 m depth) for four years. Seven specimens showed sex reversal from female to male during indoor rearing condition, whose total length and body weights were from 63.0 to 99.0 cm and from 4.4 to 13.2 kg, respectively. After inducing artificial masculinization in 14 female E. bruneus with a 17${\alpha}$-methyltestosterone (2.0 mg/kg BW) implants for 3 years, spermiation occurred in 9 specimens (total length: 54.0 to 68.0 cm, body weight: 2.3 to 4.3 kg). Among the female to male sex reversals, two specimens returned back to being female, whose body weights were 2.8 kg (initially 2.6 kg) and 2.7 kg (initially 2.3 kg). Therefore, this study suggested that E. bruneus (> 3.0 kg) was more effective in masculinizing by 17${\alpha}$-methyltestosterone implants.

• Journal of Aquaculture
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• v.18 no.3
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• pp.167-172
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• 2005

Sex reversal to a functional male of sevenband grouper $(41.0{\pm}1.3cm\;TL,\;1.4{\pm}0.1kg\;BW)$ was induced by $17{\alpha}-methyltestosterone\;(MT,\;0.5\sim2.0mg/kg\;BW)$ implantation from March 17 to May 12,2002. Gonad of control group was composed of genial cells and peri-nucleolus oocyte during the experimental period. Gonad of fish treated with 0.5 mg MT/kg BW had peri-nucleolus oocytes, spermatogonia, spermatids and spermatozoa at the late stages of spermatogenesis, while the fish group treated with 1.0 and 2.0 mg MT/kg BW contained spermatoza in the efferent duct. Sperm were obtained from the experimental groups treated with a dose of $1.0{\sim}2.0mg$ MT/kg BW. In the MT treated groups, testosterone and 11-ketotestosterone levels were higher than those in the control group during the $2{\sim}6$ weeks of the experimental period (P<0.05). $Estradiol-17{\beta}$ was detected from fish in the experimental fish.

• Journal of Aquaculture
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• v.8 no.3
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• pp.183-193
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• 1995

Blue tilapia, Oreochromis aureus swim-up fry were fed,0, 1, 10, or 60 ppm $17\alpha-methyltestosterone$(MT) for 30 days (sex reversal period). Fish that had been fed 0 ppm MT during the sex reversal period were subsequently fed 0 ppm MT (0-0), 10 ppm MT (0-10) or 60 ppm MT (0-60) for the next 57 days (post sex reversal period) ; fish that had been fed 60 ppm MT during the sex reversal period were subsequently fed 0 ppm MT (60-0), 10 ppm MT (60-10), or 60 ppm MT (60-60) during the post sex reversal period. One group was fed 1 ppm MT (1-1), while another group was fed 10 ppm MT (10-10) during the entire 87-day experiment. There was a significant inverse relationship between concentration of MT and percentage body protein and percentage body fat at the end of the sex reversal period, while there was a significant positive relationship between concentration of MT and percentage body moisture. MT treatment during the post sex reversal period had greater effects on body composition of males at the end of the post sex reversal period than did MT treatment during the sex reversal period. There was a significant inverse relationship between MT concentrations, during both the sex reversal and post sex reversal periods, and gonosomatic indices (GSI) in males. In females, there was a significant inverse relationship between MT concentrations during the post sex reversal period and GSI.

• Development and Reproduction
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• v.18 no.3
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• pp.127-131
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• 2014

We investigated the androgenic effects of $17{\alpha}$-methyltestosterone (MT) on gonadal sex reversal in juvenile red spotted grouper Epinephelus akaara. The fish were immersed in $17{\alpha}$-MT at 1 and 5 mg/L. Treatment method of $17{\alpha}$-MT was once weekly for 4 and 8 weeks. Fish were sampled at 12 months after end of the treatment period in order to histological analysis. At the initiation of an experiment (70 day after hatching), juvenile red spotted grouper have the paired primordial gonads with somatic cells bellow kidney in the posterior portion of the body cavity. Formation of ovarian cavity indicates that the ovarian differentiation beginning at 70 DAH in red spotted grouper. At 12 months after end of the treatment period, control group, $17{\alpha}$-MT 1 mg/L treatment group for 4 and 8 weeks, and $17{\alpha}$-MT 5 mg/L treatment group for 4 weeks were all female. However, sex-changed males without ovarian cavity were observed in the $17{\alpha}$-MT 5 mg/L treatment group for 8 weeks. In grouper, we firstly reported that the red spotted grouper be able to induce the primary males by hormone treatment prior to gonadal sex differentiation.

• Environmental Engineering Research
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• v.21 no.4
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• pp.384-392
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• 2016

The aim of this study was to investigate the removal efficiency of $17{\alpha}$-methyltestosterone (MT) from aqueous solution by Salvinia cucullata Roxb. ex Bory in an active plant-based reactor with a specific focus on linear regression analysis for the sorption phenomena of MT onto the plant roots. A high performance liquid chromatographic method using UV detection (245 nm) was used to analyse the samples. The batch experiments of the active plant reactor (APR) were established to investigate the ability of Salvinia cucullata to remove MT from the liquid phase. The results revealed that 40% and 60% removal of MT from the liquid phase was observed at 5 min. and at 4 h, respectively. Salvinia cucullata can effectively remove MT from the aqueous solution in APRs. Kinetic studies revealed that the sorption phenomena of MT by Salvinia is best described using a linearized pseudo - second order model. Based on the kinetic parameters, it is likely that during the first 4 h of the contact (t = 0 to t = 4 h) sorption is the major driving mechanism of the disappearance of MT from aqueous solutions. However, at higher MT concentrations, diffusivity of MT has a significant effect on the migration of MT from the bulk stream to the root surface. The isotherm analysis revealed that the sorption kinetics favourably followed pseudo second-order. The results of isotherm analysis have indicated that the sorption of MT onto the root surfaces of Salvinia cucullata was favourable and almost irreversible.

• Fisheries and Aquatic Sciences
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• v.14 no.1
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• pp.11-15
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• 2011

We examined the effects of 17${\alpha}$-methyltestosterone (MT) on growth and induced sex change in the longtooth grouper Epinephelus bruneus. The growth rate for body weight (GRW) and specific growth rate (SGR) of the group injected with MT over 8 weeks were significantly higher than those of the sham-injected control group, the group injected over 4 weeks, and the control group. Of the orally administrated groups, the GRWs of the control group and the group given 1 kg of feed with 2.0 mg of MT were highest and did not significantly differ from one another. For SGR, the treatment groups differed significantly, and the SGR of the control group was higher than those of the other groups (P<0.05). The condition factor (CF) of the group injected over 4 weeks was higher than those injected over 8 weeks, the sham-injected control group over 8 weeks, and the control group. The CF did not significantly differ between the sham-injected control group over 8 weeks and the injected group over 8 weeks, but these two groups differed from the control group (P<0.05). The CFs of the groups given 1 kg of feed with 0.5, 1.0, and 2.0 mg of MT were significantly higher than that of the control group (P<0.05). The feed efficiency ratio was not significantly affected by MT administration. Most of the experimental groups receiving MT developed many unidentified germ cell cysts and perinucleolus oocytes, although neither spermazoa cells nor sex-changed males were observed in any of the treatments.

• Journal of Life Science
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• v.20 no.12
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• pp.1902-1905
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• 2010

This study was conducted to increase the efficiency of farming practice in rainbow trout, Oncorhynchus mykiss, by sex reversal and chromosome-set manipulation techniques. Induction of sex-reversed gynogenetic diploid rainbow trout males and mass production of all-female rainbow trout by genetic sex reversal was performed. Phenotypic males in the gynogenetic diploid group were induced successfully by dietary administration of 5 mg of 17 alpha-methyltestosterone per kg diet for 82 days. All females were produced by crossing between normal female and sex-reversed gynogenetic diploid male rainbow trout.

• Journal of Life Science
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• v.20 no.11
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• pp.1634-1639
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• 2010

This study was conducted to increase the efficiency of farming practice in rainbow trout, Oncorhynchus mykiss, by sex reversal and chromosome-set manipulation techniques. To obtain phenotypic males, hormonal sex reversal was carried out using an exogenous hormone treatment method. 5 mg of 17 alpha-methyltestosterone per kg diet was supplied for 82 days after first feeding at $10^{\circ}C$ and $13^{\circ}C$. More than 93% of the male population was produced by this method and growth of hormone-treated fish at $13^{\circ}C$ was faster than that of untreated bi-sexual groups. Induced diploid gynogenesis was carried out using artificial insemination of UV-irradiated sperm into haploid eggs. Based on the appearance of the rate of haploid syndrome and survival of embryo, a UV ray dose of at least $3,600\;erg/cm^2$ was required to inactivate rainbow trout sperm genetically. Haploid embryos were restored to diploid by blocking the extrusion of the second polar body using heat shock treatment at $28^{\circ}C$ for 20 min, 10 min post insemination. Gynogenetic diploid sex ratios were confirmed after maturation of the fish erythrocyte measurements and chromosome counts.