Pollution of aquatic ecosystems poses a serious threat to aquatic organisms and ultimately the entire ecosystem. Understanding how a toxin affects embryonic development is key to determining the risk a pollutant represents to the environment. Extraembryonic membranes, such as the chorion of fish eggs, provide a protective barrier between the embryo and the environment. Although the fish chorion excludes many chemical pollutants, some noxious agents can still gain access to the aquatic embryo. Therefore a monitoring system that tests the effects directly upon the embryo must be established. Although exposure to a single toxin in the laboratory can determine the concentration at which a pollutant becomes a health or environmental hazard, embryos and adults in nature are not merely affected by a single chemical, but are exposed to mixtures of different pollutants. Zebrafish (Danio rerio) and medaka (Oryzias latipes) embryos were employed for the rapid observation of the effects of single chemicals and chemical mixtures on development. Using dechorionation and a perivitelline space microinjection system, the embryos were effective sentinels for low concentrations of aquatic pollutants. The developmental effects of small quantities of toxins were observed. Embryos treated during the late gastrula stage of development with hexachlorobenzene (HCB); 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD); toluene; benzene; or mixtures of these chemicals developed cardiovascular abnormalities. The zebrafish dechorionation exposure technique, Micro Intrachorionic Zebrafish Embryo Live Laboratory test, was especially effective in testing the pollutant mixtures. Combinations of both TCDD and benzene (as well as the toluene and benzene combinations) were tested and the mixtures acted synergistically; the combinations were more toxic than either chemical by itself. Hexachlorobenzene- and TCDD-treated embryos tested positively for expression of cytochrome P450 1A indicating that the cytochrome metabolic pathways were already functional in these early embryos, and suggested that a product of the cytochrome system may be involved in HCB and TCDD pollution associated cardiovascular defects.

译文

水生生态系统的污染严重威胁着水生生物,并最终威胁到整个生态系统。了解毒素如何影响胚胎发育是确定污染物对环境构成风险的关键。胚外膜(例如鱼卵的绒毛膜)在胚胎和环境之间提供了保护性屏障。尽管鱼绒毛膜排除了许多化学污染物,但某些有害物质仍可进入水生胚胎。因此,必须建立一个直接测试对胚胎的影响的监测系统。尽管在实验室中暴露于单一毒素可以确定污染物对健康或环境有害的浓度,但自然界中的胚胎和成年不仅受到单一化学品的影响,而且还暴露于不同污染物的混合物中。斑马鱼(Danio rerio)和medaka(Oryzias latipes)胚胎用于快速观察单一化学物质和化学混合物对发育的影响。使用去绒毛膜切开术和玻璃体周围微注射系统,胚胎是低浓度水生污染物的有效前哨。观察到少量毒素的发育影响。在发育后期的胃胚期用六氯苯(HCB)处理过的胚胎; 2,3,7,8-四氯二苯并-对二恶英(TCDD);甲苯;苯;或这些化学物质的混合物会导致心血管异常。斑马鱼的去绒毛膜暴露技术,微内绒毛膜斑马鱼胚胎活体实验室测试,在测试污染物混合物方面特别有效。测试了TCDD和苯的组合(以及甲苯和苯的组合),并且混合物起了协同作用。这些组合物本身比任何一种化学物的毒性都大。六氯苯和TCDD处理的胚胎对细胞色素P450 1A的表达进行了阳性测试,表明这些早期胚胎中的细胞色素代谢途径已经起作用,并表明该细胞色素系统的产物可能与HCB和TCDD污染相关的心血管缺陷有关。

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