Abstract
Background: Bohai Red, a new Argopecten scallop strain selected from the hybrids between the Peruvian scallop, Argopecten purpuratus and the bay scallop northern subspecies, A. irradians irradians, is now one of the most cultured scallop strains in northern China. As one of a series of studies focusing on adaptation of Bohai Red scallops to fluctuations in environmental factors, this study aimed to examine the expression profile of Wnt genes in response to different temperature stresses in Bohai Red. Results: As Bohai Red scallops were originated from the hybrids between the Peruvian scallop and the bay scallop northern subspecies, we first identified all Wnt genes from the genomes of the Peruvian scallop and the bay scallop northern subspecies, as well as the bay scallop southern subspecies, A. i. concentricus. Twelve Wnt members were identified from the two subspecies of bay scallop, and 13 Wnt genes were found in the genome of the Peruvian scallop. Protein structure analyses showed that most Wnt genes poses all 5 conserved motifs except Wnt 1, Wnt 2, Wnt 6 and Wnt 9 in the bay scallops and Wnt2 and Wnt9 in the Peruvian scallop. Unexpectedly, Wnt8 gene was present while Wnt3 was absent in both the bay scallops and the Peruvian scallop. Phylogenetic analysis revealed that Wnt3 may have disappeared in the early evolution of mollusks. The expression profile of Wnt genes in Bohai Red exposed to different temperatures were examined by qRT-PCR. The results showed that expression of Wnt genes responded differentially to temperature changes. The Wnt genes such as Wnt1, Wnt6, Wnt7, Wnt11 and WntA that responded slowly to low and high temperature stresses may be related to the maintenance of basic homeostasis. Other Wnt genes such as Wnt4, Wnt9, Wnt5 and Wnt2 that responded rapidly to low temperature may play an important role in organismal protection against low temperature stress. And yet some Wnt genes including Wnt10, Wnt16, and Wnt8 that responded quickly to high temperature stress may play key roles in response to organismal stress provoked by high temperature stress. Conclusions: Wnt genes are well conserved in Argopecten scallops, as in other bivalves. Wnt genes may play important roles in adaptation of Bohai Red scallops to changing temperatures. The results in this study will provide new insights into the evolution and function of Wnt genes in bivalves and eventually benefit culture of Bohai Red scallops.
Characterization of Wnt Genes in Argopecten Scallops and Their Involvement in Responses to Different Temperature Stresses in Bohai Red Scallops