Pan Luqing, Hu Dongxu, Liu Maoqi, Hu Yanyan, Liu Shengnan
The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, PR China.
The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao 266003, PR China.
Gene. 2016 Jan 15;576(1 Pt 2):347-57. doi: 10.1016/j.gene.2015.10.049. Epub 2015 Oct 23.
Carbonic anhydrase (CA) is involved in ion transport, acid-base balance and pH regulation by catalyzing the interconversion of CO2 and HCO3(-). In this study, full-length cDNA sequences of two CA isoforms were identified from Portunus trituberculatus. One was Portunus trituberculatus cytoplasmic carbonic anydrase (PtCAc) and the other one was Portunus trituberculatus glycosyl-phosphatidylinositol-linked carbonic anhydrase (PtCAg). The sequence of PtCAc was formed by an ORF of 816 bp, encoding a protein of 30.18 kDa. The PtCAg was constituted by an ORF of 927 bp, encoding a protein of 34.09 kDa. The deduced amino acid sequences of the two CA isoforms were compared to other crustacean' CA sequences. Both of them reflected high conservation of the residues and domains essential to the function of the two enzymes. The tissue expression analysis of PtCAc and PtCAg were detected in gill, muscle, hepatopancreas, hemocytes and gonad. PtCAc and PtCAg gene expressions were studied under salinity and pH challenge. The results showed that when salinity decreased (30 to 20 ppt), the mRNA expression of PtCAc increased significantly at 24 and 48 h, and the highest value appeared at 24h. The mRNA expression of PtCAg had the same situation with PtCAc. However, when salinity increased (30 to 35 ppt), only the mRNA expression of PtCAc increased significantly at 48 h. When pH changed, only the mRNA expression of PtCAc increased significantly at 12h, which was under low pH situation. The mRNA expression of PtCAg increased significantly at 12-48 h, and there was no significant difference of the expression between the pH challenged group and the control group in other experimental time. The results provided the base of understanding CA' function and the underlying mechanism in response to environmental changes in crustaceans.
碳酸酐酶（CA）通过催化二氧化碳和碳酸氢根离子（HCO3-）的相互转化参与离子运输、酸碱平衡和pH调节。在本研究中，从三疣梭子蟹中鉴定出两种CA亚型的全长cDNA序列。一种是三疣梭子蟹细胞质碳酸酐酶（PtCAc），另一种是三疣梭子蟹糖基磷脂酰肌醇连接的碳酸酐酶（PtCAg）。PtCAc的序列由一个816 bp的开放阅读框组成，编码一个30.18 kDa的蛋白质。PtCAg由一个927 bp的开放阅读框构成，编码一个34.09 kDa的蛋白质。将这两种CA亚型推导的氨基酸序列与其他甲壳类动物的CA序列进行比较。它们都反映出对这两种酶功能至关重要的残基和结构域具有高度保守性。对PtCAc和PtCAg进行了鳃、肌肉、肝胰腺、血细胞和性腺的组织表达分析。研究了PtCAc和PtCAg基因在盐度和pH值挑战下的表达情况。结果表明，当盐度降低（从30到20 ppt）时，PtCAc的mRNA表达在24小时和48小时显著增加，最高值出现在24小时。PtCAg的mRNA表达与PtCAc情况相同。然而，当盐度升高（从30到35 ppt）时，只有PtCAc的mRNA表达在48小时显著增加。当pH值变化时，只有PtCAc的mRNA表达在12小时显著增加，此时处于低pH环境。PtCAg的mRNA表达在12 - 48小时显著增加，在其他实验时间，pH值挑战组和对照组之间的表达没有显著差异。这些结果为理解甲壳类动物中CA的功能及其响应环境变化的潜在机制提供了基础。
