National Engineering Research Center of Marine Facilities Aquaculture, Zhejiang Ocean University, Zhoushan 316022, PR China.
National Engineering Research Center of Marine Facilities Aquaculture, Zhejiang Ocean University, Zhoushan 316022, PR China.
Mar Pollut Bull. 2018 Feb;127:717-725. doi: 10.1016/j.marpolbul.2018.01.003. Epub 2018 Jan 5.
Bivalves use anti-oxidative enzyme systems to defend themselves against excessive reactive oxygen species, which are often catalyzed by environmental pollution. As a key member of anti-oxidative enzyme family, catalase plays a crucial role in scavenging the high level of reactive oxygen species to protect organisms against various oxidative stresses. In this study, a catalase homologue was identified from Mytilus coruscus (named McCAT, KX957929). The open reading frame of McCAT was 1844bp with a 5' untranslated region of 341bp and a 3' untranslated region of 927bp. The deduced amino acid sequence was 512 residues in length with theoretical pI/MW 8.02/57.91kDa. BLASTn and phylogenetic analyses strongly suggested that it was a member of catalase, also known as CAT family for its conserved catalytic site motif and proximal heme-ligand signature motif. Real-time fluorescence quantitative PCR showed that constitutive expression of McCAT was occurred, with increasing order in mantle, adductor, gill, hemocyte, gonad and hepatopancreas. It was observed that bacterial infection and heavy metals stimulation up-regulated McCAT mRNA expression in hepatopancreas with time-dependent manners. The maximum expression appeared at 8h after pathogenic bacteria injecting, with 15-fold in Vibrio parahemolyticus and 60-fold in Aeromonas hydrophila than that of 0h. The highest point of McCAT mRNA appeared at different times for exposure to heavy metals with copper at day 5 (0.1mg/L 30-fold, 0.5mg/L 15-fold, 1.5mg/L 6-fold) and plumbum at day 3 (3.0mg/L 20-fold). The enzymatic activity analysis found that McCAT activity in the gill of M. coruscus was affected by heavy metals concentration. The results suggested that McCAT plays a significant role in antioxidation and the expression of McCAT can be used as a biomarker for detection of marine environmental pollution.
双壳类动物使用抗氧化酶系统来抵御过量的活性氧，而这些活性氧通常是由环境污染所催化的。作为抗氧化酶家族的关键成员，过氧化氢酶在清除高水平的活性氧方面起着至关重要的作用，以保护生物免受各种氧化应激。在本研究中，从贻贝（Mytilus coruscus）中鉴定出一种过氧化氢酶同源物（命名为 McCAT，KX957929）。 McCAT 的开放阅读框为 1844bp，5'非翻译区为 341bp，3'非翻译区为 927bp。推导出的氨基酸序列长 512 个残基，理论等电点/MW 为 8.02/57.91kDa。BLASTn 和系统发育分析强烈表明它是过氧化氢酶的一个成员，因其保守的催化位点基序和近端血红素配体特征基序而被称为 CAT 家族。实时荧光定量 PCR 显示 McCAT 存在组成型表达，在套膜、闭壳肌、鳃、血细胞、性腺和肝胰腺中的表达量逐渐增加。观察到细菌感染和重金属刺激会随时间依赖性方式上调肝胰腺中的 McCAT mRNA 表达。在注射病原菌 8 小时后，McCAT mRNA 的表达量达到最大值，与 0 小时相比，副溶血弧菌和嗜水气单胞菌分别增加了 15 倍和 60 倍。暴露于重金属时，McCAT mRNA 的最高点出现在不同的时间，其中铜在第 5 天（0.1mg/L 增加 30 倍，0.5mg/L 增加 15 倍，1.5mg/L 增加 6 倍），铅在第 3 天（3.0mg/L 增加 20 倍）。酶活性分析发现，重金属浓度会影响贻贝鳃中的 McCAT 活性。结果表明，McCAT 在抗氧化中起着重要作用，McCAT 的表达可以作为海洋环境污染检测的生物标志物。
