Abstract
Carotenoids are a diverse group of red, orange, and yellow pigments that act as vitamin A precursors and antioxidants. Animals can only obtain carotenoids through their diets. Amongst the carotenoids identified in nature, over one third are of marine origin, but current research on carotenoid absorption in marine species is limited. Bivalves possess an adductor muscle, which is normally white in scallops. However, a new variety of Yesso scallop (Patinopecten yessoensis), the ‘Haida golden scallop’, can be distinguished by its adductor muscle's orange colour, which is caused by carotenoid accumulation. Studying the genes related to carotenoid accumulation in this scallop could benefit our understanding of the mechanisms underlying carotenoid absorption in marine organisms, and it could further improve scallop breeding for carotenoid content. Stearoyl-CoA desaturase (SCD) is the rate-limiting enzyme in the production of monounsaturated fatty acids, which enhance carotenoid absorption. Here, the full-length cDNA and genomic DNA sequences of theSCDgene from the Yesso scallop (PySCD) were obtained. ThePySCDgene consisted of four exons and three introns, and it contained a 990-bp open reading frame encoding 329 amino acids. It was ubiquitously expressed in adult tissues, embryos and larvae of both white Yesso scallops and ‘Haida golden’ scallops. Although the expression pattern ofPySCDin both types of scallops was similar, significantly morePySCDtranscripts were detected in the ‘Haida golden’ scallops than in the white scallops. ElevatedPySCDexpression was found in tissues including the adductor muscle, digestive gland, and gonad, as well as in veliger larvae. This study represents the first characterisation of anSCDgene from theMollusca. Our data imply thatPySCDfunctions in multiple biological processes, and it might be involved in carotenoid accumulation.
