We investigated the effect of tributyltin (TBT) exposure on the concentration of malondialdehyde (MDA) and the activity levels of the superoxide dismutase (SOD),catalase (CAT),and acid and alkaline phosphatase (ACP and AKP) enzymes in the small abalone,Haliotis diversicolor supertexta.We collected samples of the hepatopancreas and hemolymph 2,6,24,48,96,and 192 h after exposure to 0.35 μg (Sn)/L TBT.In the hepatopancreas,ACP activity was significantly higher in animals exposed to TBT 2,24,and 96 h post-exposure compared with the control animals.AKP activity was also higher after 2 h,but SOD and CAT activity was unchanged.The concentration of MDA in the hemolymph was significantly higher than the control animals 2 and 6 h post-exposure.In the hemolymph of animals exposed to TBT,ACP activity was significantly lower than in the control animals 192 h post-exposure,whereas AKP activity was significantly lower 2 and 192 h post-exposure.Hemolymph SOD activity and levels of MDA were significantly lower than in the control animals 24 h after exposure but significantly higher after 96 h.Our results demonstrate that exposure to TBT cause rapid changes in ACP and AKP activity as well as altering the concentration of MDA in the hepatopancreas and hemolymph.SOD and CAT do not appear to be involved in the detoxification of TBT in the hepatopancreas of small abalone.
有机锡作为防污损生物附着添加剂曾被大量使用,在极低浓度下就能诱发腹足类发生性畸变现象,严重危害了海洋生态系统的平衡。虽然三丁基锡已被国际海事组织全球禁用,但目前报道的环境有机锡污染仍然非常严重,而且其致毒机制一直众说纷纭。首先,简述了腹足类性畸变及其在世界各个海域有机锡污染监测中的应用,重点综述了有机锡致海洋腹足类性畸变分子机制的3种假说:脊椎动物类型的类固醇激素假说、神经肽假说以及视黄酸X受体(retinoid X receptor,RXR)假说,另外,结合快速发展的分子生物学技术,探讨了研究腹足类性畸变分子机制的新思路和新方法。
维甲酸X受体(retinoid X receptor,RXR)作为配体依赖的转录因子,是核受体超家族重要的一员。脊椎动物RXR与配体及其辅调节因子相互作用,调控基因的协调表达,在胚胎发育、细胞分化、新陈代谢等许多生理过程中起着重要作用。软体动物RXR的研究因其与腹足类性畸变的关系越来越受到关注。本文综述了目前获得的软体动物RXR基因的结构,比较了软体动物RXR基因各功能结构域与人类和其他动物RXR的相似性。以RXR编码区的氨基酸序列为基础,构建了系统进化树,发现软体动物RXR与脊索动物而不是其他无脊椎动物的RXR聚成一支。软体动物和甲壳动物不同RXR亚型的氨基酸序列比较发现,两类动物可能存在不同的剪切酶或剪切位点。此外论文还针对软体动物RXR的配体、二聚体伙伴以及生理功能等方面的研究进行了综述。
