菲律宾蛤仔(Ruditapes philippinarum)金属硫蛋白基因克隆及Cd^(2+)胁迫下的表达分析

CLONING AND EXPRESSION OF METALLOTHIONEIN GENE IN RUDITAPES PHILIPPINARUM EXPOSED TO CADMIUM

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 family of cysteine-rich, low molecular, and heavy metal-binding proteins. MT plays important roles in detoxifying heavy metals and regulating concentrations of trace elements. In the present study, the full-length cDNA of metallothionein was identified from Manila clam Ruditapes philippinarum(named as RpMT) by RACE approaches. The full-length cDNA of RpMT is of 570 bp, encoding 75 amino acids with characteristic repeating cysteine motifs Cys-Xn-Cys. By real time quantitative PCR, the expression profile of RpMT transcript was detected in digestive gland and gill tissues from two pedigrees of clam(white and zebra) post cadmium exposure. It was found that the expression of RpMT gene under Cd2+ stress increased significantly in both pedigrees of clam. After exposure under Cd2+, variation of RpMT mRNA expression in gill tissues was more significant than that in digestive gland in both white and zebra clams. In addition, the increase of RpMT transcript in gill tissues of white clam was more sensitive than that in the zebra clams. Therefore, RpMT may have played an important role in the detoxification of cadmium contamination.