The role of catalase in the immune response to oxidative stress and pathogen challenge in the clam Meretrix meretrix.
Catalase (CAT) can effectively eliminate H(2)O(2) and maintain the redox balance of immune system, which is essential for innate immunity. A catalase gene was cloned and its potential role in immune system was investigated in the clam, Meretrix meretrix. The catalase (MmeCAT) gene had an open reading frame of 1533 bp encoding 511 amino acids which showed high identity with that of molluscs. The distribution of MmeCAT in clam tissues was examined and the mRNA, protein expression and CAT activity paralleled with each other, with the highest expression in hepatopancreas. In response to H(2)O(2) challenge, MmeCAT mRNA showed significantly higher expression at 12 h and 24 h post-challenge in experimental clams than in control clams (P < 0.05). Meanwhile, the protein expression in experimental clams was increased to about 3 times as much as that in control clams at 6 h post-challenge. After injection with a Vibrio parahaemolyticus-related bacterium (MM21), the expression of MmeCAT mRNA was significantly up-regulated at 12 h and 24 h post-injection (P < 0.05). It suggested that MmeCAT might be involved in the immune response to Vibrio infection. To better understand the role of MmeCAT in immune system, its mRNA expression was compared between a Vibrio-resistant population and a control population after immersion challenge with MM21. The continuously increased transcription in resistant population suggested MmeCAT could benefit the immune system of clams to defend against pathogen infection. Our study indicated that the redox balance was essential for M. meretrix to resist pathogen infection.
Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
Chao
C
Wang
Xin
X
Yue
Xia
X
Lu
Baozhong
B
Liu
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D049872:Bivalvia / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000276:immunology*; D015153:Blotting, Western; D002374:Catalase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007113:Immunity, Innate; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011897:Random Allocation; D016415:Sequence Alignment; D014736:Vibrio parahaemolyticus / Q000276:immunology / Q000502:physiology
D018076:DNA, Complementary; D012333:RNA, Messenger; D006861:Hydrogen Peroxide; D002374:Catalase