Identification of mapk gene family in Lateolabrax maculatus and their expression profiles in response to hypoxia and salinity challenges.

Mitogen-activated protein kinases (MAPK) superfamily exerts crucial roles in the regulation of intracellular metabolism, gene expression as well as integral activities in diverse cellular processes. In our study, 14 mapk genes were identified in spotted sea bass (Lateolabrax maculatus) and these genes were divided into three subfamilies according to phylogenetic analysis, including 6 erk genes, 3 jnk genes and 5 p38-mapk genes. Syntenic and tertiary structure analysis confirmed their annotation and orthologies. The expression profiles of several stress-responsive mapk genes of spotted sea bass were examined in gill using quantitative real-time PCR after salinity (0‰, 12‰, 30‰, 45‰) and hypoxia challenges (DO = 1.0 ± 0.2 mg/L). After salinity challenge, significant up-regulations were observed in the expressions of mapk8 (jnk1), mapk9 (jnk2), mapk11 (p38β), mapk14a (p38a) and mapk14b (p38b). mapk8 and mapk9 were more sensitive to hypotonic challenge (0‰) than hyperosmotic (45‰) and isosmotic challenges (12‰), while the highest expression of mapk11, mapk14a and mapk14b were observed in hyperosmotic challenge (45‰). After hypoxia challenge, the expression levels of mapk1 (erk2), mapk3 (erk1) and mapk14a (p38a) in treatment group (DO = 1.0 ± 0.2 mg/L) were significantly up-regulated in comparison with control group (DO = 8.0 ± 0.5 mg/L) in time-dependent manner. These results indicated that these mapk genes in spotted sea bass may play important roles in response to salinity and hypoxia challenges.