17α-甲基睾酮对剑尾鱼的影响

目的研究17α-甲基睾酮暴露对产后雌性剑尾鱼(Xiphophorus helleri)性逆转组织形态学变化的影响,探讨剑尾鱼第二性征变化作为水环境风险评价(ERA)的有效生物学标记的可能性。方法使用浸浴法以10μg/L 17α-甲基睾酮为剑尾鱼染毒持续7周,对实验鱼的体形、腹鳍、臀鳍、尾鳍及性腺等组织器官的变化进行观察;同时对幼鱼在实验室养殖条件下的性别分化进行统计。结果 17α-甲基睾酮对产后雌鱼有明显的影响,受诱导后出现性逆转,逐渐发育形成雄性第二性征:体形变纤细;腹鳍第1鳍条变短、第2和第3鳍条延长,臀鳍第3、4、5鳍条末端钩状化且第3鳍条变粗壮,尾鳍上下缘出现增生;体内与臀鳍相连的骨骼合并生长;受诱导的雌鱼性腺呈现退化趋势并伴有卵细胞坏死现象,生殖能力受到负面影响。结论剑尾鱼臀鳍和尾鳍变化可作为水环境雄激素物质污染监测的有效生物学标记。

Effects of 17 alpha-Methyltestosterone on the Reversal of Male Resistance in Viviparous Swordtail Fish(Xiphophorus helleri)

Objective To investigate the impact of histological changes of postnatal female swordtail fish（Xiphophorus helleri） during sex-reversal caused by 17α-methyltestosterone exposure and the possibility of taking the changes of secondary sexual characteristics as biomarkers in water environmental risk assessment（ERA）.Methods Postnatal female swordtail fish were exposed to a water body containing 10 μg /L 17α-methyltestosterone for up to 7 weeks.To observe and record the changes of body shape,ventral fin,anal fin,caudal fin,gonad and sex differrntiation of juveniles under lab culture condition.Results Masculinizational changes occurred in all postnatal females： body shape became slender,the first ray of ventral fin got shorter,the second and third rays of ventral fin got longer,the ends from the third to fifth rays of anal fin came out hooks,the third ray of anal fin got thick and strong,and the upper and lower margin of caudal fin showed accrementition.The internal skeleton connecting with the anal fin showed an combined growth.The reproductive capacity was impeded due to gonad atrophy and egg degeneration.Conclution The results indicate that the changes of anal fin and caudal fin of postnatal female swordtail fish can be taken as biomarkers in the monitoring of environmental androgenic substances.