黄河环境激素污染水域鱼类繁殖特性与技术性反应机制

Species and resources of fish in the Yellow River are declining. The Yellow River has been seriously polluted. Multiplication and development of fish are disrupted by environmental hormones which can do harm to reproductive systems of fish even at very low levels. In this study, Zhengzhou section will be selected as the study area and representative sections downstream the inlets of the Yellow River (Zhengzhou section) will be selected as the study objects. In situ exposure, laboratory simulation exposure and laboratory analysis will be combined in this study. The contents and levels of environmental hormones in the Yellow River (Zhengzhou section) will be investigated. In the sections polluted by environmental hormones, reproductive characters of fish such as gonad development, fecundity, reproductive behaviours and associated social status and reproductive success will be determined. The tactical responses of fish reproduction to environmental hormones will be studied. The relations between the tactical responses of fish reproduction and contents or levels of environmental hormones are expected to be obtained. In the sections polluted by environmental hormones, neural and endocrine regulations of hypothalamus- hypophysis-gonad axes of fish with gonad development in different periods will be determined and tactical response mechanisms of fish reproduction to environmental hormones are expected to be clarified. The results have important scientific significance for water and fish protection and biodiversity maintenance in the aquatic ecosystem of the Yellow River.

黄河鱼类物种多样性和资源量明显下降。黄河水环境污染严重，低浓度的环境激素可对鱼类繁殖系统造成损伤，影响鱼类繁衍发展。本课题以黄河郑州段为研究区域，以黄河郑州段入河排污口下游典型断面为研究对象，采取实地原位暴露、室内模拟暴露及实验室分析研究方法，分析黄河郑州段环境激素组成与污染水平；研究黄河环境激素污染水域鱼类的繁殖特性如性腺发育过程、繁殖力、繁殖行为以及与繁殖行为密切相关的社会等级结构及繁殖成功率，分析鱼类繁殖对环境激素污染的技术性反应及其与环境激素组成和污染水平的联系；研究黄河环境激素污染水域鱼类繁殖周期内性腺发育不同时期下丘脑-垂体-性腺轴的神经-内分泌调控作用，阐明鱼类繁殖对环境激素污染的技术性反应机制。研究成果对保护黄河水环境和鱼类资源，维护黄河水生生态系统生物多样性具有重要的科学意义。

在黄河郑州段主要支流（伊洛河、新蟒河、沁河）入河口下游及花园口水文站下游设置典型断面。采用MVLN细胞转录报告检测和体内实验研究了四个典型断面的雌激素污染水平。MVLN实验结果表明伊洛河、新蟒河、沁河和花园口典型断面的雌二醇当量分别为1.09、0.72、1.19和0.80 ng/L。伊洛河和沁河典型断面水样30天暴露显著诱导了雄性日本青鳉肝脏内卵黄蛋白原合成。沁河断面水样暴露明显提高了雄鱼肝肉指数。新蟒河断面水样暴露导致了鱼卵孵化时间的延迟，伊洛河和新蟒河典型断面水样导致鱼的存活率显著降低。将经各典型断面水样暴露孵化出的仔鱼继续采用黄河水样暴露，分别于20、40和60天后取样，对雌鱼和雄鱼进行性腺发育组织学检查。结果表明，伊洛河和沁河典型断面水样20天暴露导致了雄鱼精原细胞总数降低。孵化出的仔鱼暴露40天后，伊洛河、沁河和花园口断面水样均抑制了雄鱼性腺发育，伊洛河、新蟒河、沁河断面水样暴露组雌鱼均出现性腺发育组织病理学改变，其中伊洛河断面水样暴露组闭锁卵泡所占比例最高。黄河典型断面水样暴露60天后，各暴露组雄鱼生精细胞比例及雌鱼各类卵母细胞比例较对照组相比均有不同，各暴露组雄鱼性腺发育均存在病理学损伤，除新蟒河断面外，各暴露组雌鱼切片均发现性腺组织病理学改变。以斑马鱼为模型生物，根据雄鱼的进攻性确定其进攻性社会等级，结果表明伊洛河和新蟒河典型断面水样21天暴露导致主导雄鱼对从属雄鱼的进攻行为较暴露前显著降低，伊洛河和花园口典型断面水样暴露组两雄鱼之间的进攻总次数差值较暴露前降低，沁河和花园口典型断面水样暴露组两雄鱼对雌鱼的进攻总次数差值较暴露前降低。采用微卫星标记法研究黄河典型断面水样暴露前后每尾雄鱼的繁殖成功率，结果表明伊洛河和沁河典型断面内分泌干扰物导致雄鱼繁殖地位及繁殖成功率发生彻底改变。通过黄河环境激素污染水域鱼类神经-内分泌调控作用分析可知，雄鱼性腺中11-酮基睾酮和脑中多巴胺水平与其进攻性密切相关，而性腺中睾酮含量是决定其繁殖成功率的关键因子。该研究从分子、基因水平上揭示了黄河环境激素污染水域鱼类繁殖技术性反应及机制，研究成果对保护黄河生态水环境和鱼类资源，维护黄河水生生态系统生物多样性具有重要的科学意义。