Comprehensive analysis of MAPK cascade genes in mollusks and their expression patterns in noble scallop Chlamys nobilis under low temperature stress

MAPK cascade proteins, including MAPK, MAPK kinases (MAPKK), and MAPKK kinases (MAPKKK) are evolutionarily conserved and exhibit diverse functions, such as energy metabolism, embryonic development, cell differentiation, apoptosis, and responses to external stress. To elucidate the evolutionary relationships of the mitogen-activated protein kinase (MAPK) cascade genes in mollusks, this study selected 54 mollusk genomes as references for systematic screening and comparison of MAPK cascade genes. The results revealed significant variation in gene numbers between Gastropoda and Cephalopoda compared to Bivalvia, with a particularly notable expansion in the MAPKKK gene family. Taking the noble scallop (Chlamys nobilis) from the Bivalvia as an example, we conducted a detailed analysis of the protein structure and conserved motifs of the MAPK cascade genes, indicating a high degree of sequence variability in the MAPKKK genes. Furthermore, we explored the expression patterns of the MAPK cascade genes in various tissues and analyzed their expression differences under chronic and acute low-temperature stress, revealing distinct adaptive strategies employed by mollusks in response to low-temperature stress. Overall, this study not only clarifies the evolutionary relationships of the MAPK cascade genes in mollusks but also characterizes their expression patterns under environmental stress, providing new insights into the adaptive mechanisms of mollusks to environmental changes.