Molecular Characterization and mRNA Expression of ISP2 and ISP4 in the Large Yellow Croaker (Larimichthys Crocea) Under Acute Cold Stress

Abstract

Ice structure proteins (ISPs), also known as antifreeze proteins, can lower the point of freezing by inhibiting the growth of ice crystals and protect organisms from freezing temperatures. The large yellow croaker (Larimichthys crocea) is an important warm-temperate marine fish in Chinese aquaculture. Only a few ISP studies have been reported in this fish to date. In this study, the cDNA of ISP2 were cloned and characterized, and mRNA expression of ISP2 and ISP4 was assessed in different tissues of the large yellow croaker under different periods of acute cold stress (0, 6, 12, 24, 48 and 72 h, rewarming after 12 and 24 h). We found that ISP2 cDNA is 861 bases in length, encoding a protein of 168 amino acid residues. The mRNA expression of ISP2 and ISP4 in tissues of large yellow croaker under different periods of acute cold stress changed significantly. In comparison with the control group, ISP2 expression increased dramatically in the heart (1,976 fold) and intestine (26 fold) after 3 h of acute cold stress and increased 43 fold in the spleen after 6 h. ISP4 expression was up-regulated significantly in the brain (43 fold) and gill (376 fold) at 1 h acute cold stress, and increased 2,774 fold in the intestine at 3 h, 64 fold in muscle and 141 fold in the spleen after rewarming for 1 h after 12 h acute cold stress. These results indicate that ISP2 and ISP4 may play an important role in the response of large yellow croaker to acute cold stress.