Cloning and expression of vitellogenin (Vg) gene and its correlations with total carotenoids content and total antioxidant capacity in noble scallop Chlamys nobilis (Bivalve: Pectinidae)

Abstract

As a nonpolar molecular carrier and a storage protein, vitellogenin (Vg) cannot only combine and transfer lipids, proteins, vitamin and carotenoids to oocytes during the oogenesis, but also be linked with the host immune defense. In this study, the full-length cDNA encoding Vg in noble scallop Chlamys nobilis was cloned. The complete Vg cDNA consists of 7760 nucleotides with an open reading frame encoding 2289 amino acid residues. Phylogenetic analysis of Vg gene revealed that Ch. nobilis was clustered together firstly with its sister species Chlamys farreri and another scallop Mizuhopecten yessoensis, then with other mollusks such as oyster and abalone, and finally with vertebrates. Tissue-specific checking results indicated that Vg gene was only expressed in the ovary. At different gonadal development stages, both orange and brown shell color scallops show the same trend that the amount of Vg mRNA expression kept at a high level at the growing stage, then dramatically decreased at the mature stage, and finally resumed to higher level at the post-spawning stage. Another very important finding is that significantly positive correlations existed between the Vg gene expression level and total carotenoids content, as well as total antioxidant capacity. The relationship among them needs further study.