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金属硫蛋白(Metallothionein,MT)是一类富含半胱氨酸的小分子蛋白质,参与机体重金属解毒和金属元素代谢等生理过程。本研究采用RACE技术,克隆获得了菲律宾蛤仔(Ruditapes philippinarum)金属硫蛋白(RpMT)的全长cDNA序列。RpMT的cDNA全长为570bp,编码75个氨基酸,包含15个MT所特有的Cys-Xn-Cys结构。采用实时荧光定量PCR技术,分析了两种壳色菲律宾蛤仔(白蛤和斑马蛤)RpMT基因在Cd2+暴露后的表达变化。结果发现:Cd2+急性和亚慢性暴露均可导致两种壳色蛤仔消化腺和鳃组织RpMT基因表达量的显著上调;暴露后两种壳色蛤仔鳃组织RpMT基因表达量的增加幅度均高于消化腺组织,且以白蛤鳃组织基因表达水平的上调幅度较高。上述结果表明,RpMT可能在菲律宾蛤仔抵御Cd2+胁迫过程中发挥了重要作用。
Metallothionein (MT) is a kind of small-molecule protein rich in cysteine, which is involved in the physiological processes such as heavy metal detoxification and metal element metabolism. In this study, the full-length cDNA sequence of RpTT from Ruditapes philippinarum was cloned by RACE technique. The full-length cDNA of RpMT is 570bp and encodes 75 amino acids. It contains 15 Cys-Xn-Cys structures unique to MT. The real-time fluorescent quantitative PCR technique was used to analyze the expression changes of RpMT gene in two shellfish species, Ruditapes philippinarum and Zebra clam, after Cd2 + exposure. The results showed that both acute and subchronic exposure of Cd2 + could result in significant up-regulation of RpMT gene expression in the digestive gland and gill tissues of both species. The increase of RpMT gene expression in the gill tissues of both species In the digestive gland tissues, the up-regulation of gene expression levels in the gill tissues of the white clams was higher. The above results indicate that RpMT may play an important role in the defense of the clams in the Philippines against Cd2 + stress.