Characterization of a novel catalase gene and its response to low temperature stress in noble scallop Chlamys nobilis with different total carotenoids content

Abstract

Antioxidant system plays important roles in organisms under environmental stress by eliminating hydrogen peroxide. Catalase is an indispensable antioxidant protein that is essential for maintaining the redox balance of innate immune system. In this study, a novel catalase gene was first cloned from noble scallop Chlamys nobilis (named as CnCAT), and then its potential roles in respond to low temperature stress were investigated using golden (rich in carotenoids) and brown (less in carotenoids) C. nobilis. The CnCAT contains an ORF of 1569 bp encoding 522 amino acids. Phylogenetic tree analysis of CnCAT showed it had a higher identity with other molluscs. The distribution analysis indicated that the highest and the lowest expression level of CnCAT were found in gill and adductor respectively. Under low temperature stress, CnCAT expression level and CAT activity were significantly up-regulated, suggesting they play important roles in defence against the low temperature stress. In addition, the expression levels of CnCAT and CAT in golden scallops were significantly higher than those of brown scallops under low temperature stress, suggesting that the high carotenoid levels in the golden scallops may strengthen their toleration to low temperature stress. Collectively, these results indicated that CnCAT plays vital roles in the antioxidant system, and carotenoids in golden scallops may enhance their resistance to low temperature stress. These results will provide us a better understand to the immune response of scallops under low temperature stress.