Papers by Author: Deng Hang Yu

Abstract: This study investigated the effects of busulfan on sex reversal in the Asian swamp eel (Monopterus albus) by evaluating the estradiol (E2) and testosterone (T) concentrations, gonadosomatic index (GSI) and sex ratio. Fish (9.80 ± 1.07 g average initial weight; n = 3 per group) were fed with five diets containing 0 (control), 10, 30, 50 or 70 mg kg-1 dietary busulfan concentrations to apparent satiation for 15 months. Serum E2 and T concentrations were determined by radioimmunoassay techniques. Both E2 and T concentrations were significantly affected by busulfan, while there were no significant differences among the treated groups. Serum E2 concentrations and GSIs decreased, while T concentrations increased with increasing busulfan levels in each group. A shift in the sex ratio towards more male and intersex fish was observed with increasing busulfan contents. The highest male ratio obtained in the 70 mg kg-1 group was significantly different compared to the other groups. High doses of busulfan may induce deformed individuals and high mortality in M. albus. Therefore, busulfan may inhibit gonad development and promote the sex change from female to male M. albus.

Abstract: The aim of this study was to investigate the effects of exogenous melatonin on sex reversal in the rice eel (Monopterus albus). This was carried out by evaluating the estradiol (E2) and testosterone (T) concentrations, gonadosomatic index (GSI) and sex ratio. Fish (9.80 ± 1.20 g average initial weight; n = 3 per group) were fed with one of five practical diets containing 0 (control), 10, 30, 50 or 70 mg kg-1 dietary melatonin contents to apparent satiation for fifteen months. Serum E2 and T concentrations were determined by radio immunoassays. E2 and T concentrations, GSIs and survival rates significantly decreased with increased concentrations of exogenous melatonin. Fish fed 70 mg kg-1 of dietary melatonin showed significantly lower rates of E2, T, GSIs and survival ratio than those fed with lower melatonin concentrations or the control group. The shift of sex ratio towards more male and intersex fish was correlated with increasing dietary melatonin contents. Therefore, a high dosage of melatonin may inhibit gonadal development and promote sex change from female to male in M. albus.