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6553879 
Journal Article 
Production of neo-males from gynogenetic yellow drum through 17α-methyltestosterone immersion and subsequent application for the establishment of all-female populations 
Xu, D; Yang, F; Chen, R; Lou, B; Zhan, W; Hayashida, T; Takeuchi, Y 
2018 
1 
Aquaculture
ISSN: 0044-8486
EISSN: 1873-5622 
489 
154-161 
English 
WOS:000427817400019 
Mono-sex culture of yellow drum (Nibea albiflora) provides economic advantages in industry because of the superior growth of females relative to males. Sex-reversal of genetic females (XX) to produce neo-males is an indispensable step toward establishing all-female populations. To achieve this goal, gynogenetic yellow drum at an undifferentiated sex stage (total length, 1.63 +/- 0.16 cm) were immersed in 17 alpha-methyltestosterone (17 alpha-MT) for 2 h/day from 30 to 90 dph (60 days), producing sex-reversed fish (neo-males). All the four 17 alpha-MT concentrations tested (0.2, 2, 10, 50 mu g/L) drove the development of testes, evidenced by histological observations of the gonads. The masculinization of gynogenetic yellow drum was also demonstrated by the expression patterns of two sex-specific genes, dmrt1 and cyp19a1a: the gonads of 17 alpha-MT-treated fish exclusively expressed male-specific dmrt1 with no expression of female-specific cyp19a1a. Specifically, treatment with 0.2 mu g/L 17 alpha-MT yielded complete sex-reversed fish without any abnormalities in gonadal development, and the growth of neo-males was not significantly different to that of controls during the treatment period. However, testicular abnormalities were observed in groups treated with higher 17 alpha-MT concentrations, with a trend for more abnormalities with increasing 17 alpha-MT concentrations, and the growth of 17 alpha-MT-treated fish was retarded at these higher 17 alpha-MT concentrations. These results indicated that high concentrations of 17 alpha-MT had adverse effects on growth and gonadal development, and the most efficient concentration tested for producing neo-males was 0.2 mu g/L. Furthermore, crossing of gynogenetic sex-reversed males with normal females produced 100% females, demonstrating the potential efficiency of this protocol for reversing the sex of yellow drum and establishing large-scale production of all-female populations. 
Nibea albiflora; 17 alpha-Methyltestosterone; sex-reversal; gonadal structure; neo-male; all-female population