Identification, Characterization, and Expression Analysis Reveal Diverse Regulated Roles of Three MAPK Genes in Chlamys farreri Under Heat Stress.

Mitogen-activated protein kinase (MAPK) cascades are fundamental signal transduction modules in all eukaryotic organisms, participating growth and development, as well as stress response. In the present study, three MAPK genes were successfully identified from the genome of , respectively, named , , and , and only one copy of , , and were detected. Domain analysis indicated that s possessed the typical domains, including S_TKc, Pkinase, and PKc_like domain. Phylogenetic analysis showed that three s of MAPK subfamilies exists in the common ancestor of vertebrates and invertebrates. All s specifically expressed during larval development and in adult tissues, and the expression level of and was apparently higher than that of . Under heat stress, the expression of and were significantly downregulated and then upregulated in four tissues, while the expression of increased in all tissues; these different expression patterns suggested a different molecular mechanism of for bivalves to adapt to temperature changes. The diversity of and their specific expression patterns provide valuable information for better understanding of the functions of MAPK cascades in bivalves.