文档介绍：摘要贝类养殖是我国传统海水养殖业中的重要组成部分。贝类通常利用滩涂进行养殖,而滩涂是海洋环境中受人类活动影响最为严重的区域。我国滩涂面积广阔, 随着滩涂生态与环境状况的恶化,以及病害的不断爆发,滩涂贝类的养殖面临重大的威胁。贝类受到各种压力胁迫刺激时,往往导致机体活性氧自由基的产生。依靠活性氧分子极强的反应特性,实现对入侵病原的杀灭。但是这种机制不具特异性, 因而也会破坏生物体自身的生物膜、蛋白分子及核酸等,诱导细胞凋亡,对机体造成严重的伤害。机体的抗氧化防御系统能够及时清除活性氧,维持机体内氧环境平衡,保护机体免受氧化损伤。其中,过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GPX)是抗氧化防御系统的关键酶类。四角蛤蜊作为一种典型的埋栖型滩涂贝类,广泛分布在我国、韩国和日本沿海,是我国主要的经济贝类之一,也是开展滩涂增养殖的优质品种。其埋栖生活的特性,对沉积物污染有较好的指示作用。本研究采用同源克隆的方法,对四角蛤蜊过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GPX)基因进行克隆,首次得到过氧化氢酶(CAT)基因cDNA片段,共780bp,编码211个氨基酸。具有在大多数物种中较为保守的CAT基因的特征性序列结构,查找到一个CAT基因催化活性位点Asn145,以及9个NADPH的结合位点。通过系统进化树的构建,表明四角蛤蜊CAT基因与硬壳蛤及文蛤的亲缘关系较近。关键词:四角蛤蜊;过氧化氢酶;谷胱甘肽过氧化物酶;基因克隆 Molecular Cloning of Catalaseand Glutathione Peroxidase Antioxidant Enzyme Genes in Mactra Veneriformis Abstract Shellfish farming is an important part of our traditional marine aquaculture. Shellfish usually use shoals for breeding, and the shoal is the most serious area affected by human activities in the marine environment. China has a vast beach area, withthe deterioration of the shoals ecological and environmental conditions, andthe repeated outbreaks of the shoals of shellfish culture under a great threat. The shellfish under various pressure stress, oftenlead tothe bodyproduce reactive oxygen species. Rely on the highly response characteristics of reactive oxygen species, to killing of invadingpathogens. However, this mechanism is not specific, andalso destroy organisms biofilm, proteinsand nucleic acids,which can induceapoptosisand then causeserious damage to the body. The body's antioxidant defense system is capable of scavenging reactive oxygen species in a timely manner, to maintain the balance of the body oxygen environmental and protect the body from oxidative damage. Catalase (CAT) andglutathione peroxidase (GPX) arethe key enzymes of the antioxidant defense system. Mactra Veneriformisis a typical shoals shellfishwith buried, widely distributed in C