Genome-wide identification and transcriptome-based expression profiling of Wnt gene family in Ruditapes philippinarum

The Wnt genes encode a set of conserved glycoproteins regulating early development, cell proliferation and differentiation, and tissue regeneration in metazoans. In some mollusks, the knowledge of Wnt gene family has been limited because of the short of the genomic and transcriptomic resources. Ruditapes philippinarum is an economically important bivalve with a variety of shell coloration patterns and ability to regenerate its siphon. To gain a greater understanding of the evolutionary dynamics of Wnt gene family, we carried out a genome-wide identification and phylogenetic analysis of Wnt gene family in R. philippinarum and other four mollusks. A total of 12 Wnt genes were identified in the genome of R. philippinarum, and the dynamic patterns of gene conservation, loss and duplication of Wnt genes were analyzed in mollusks and model organisms. Furthermore, the transcriptome analyses demonstrated the expression profiles of the Wnt genes at different developmental stage, in adult tissues, during siphon regeneration, in four different shell color strains, and at uncolored and colored developmental stages in two different shell color strains. These findings suggest that the expansion of Wnt genes may play vital roles in the larval development, the formation of shell color pattern and siphon regeneration in R. philippinarum. This study provides a valuable insight into Wnt function and evolution in mollusks.