Identification Of Genes Relating To Carotenoids Accumulation In Adductor Muscles Of Yesso Scallops (Patinopecten Yessoensis)

The Yesso scallop (Patinopecten yessoensis) is one of most important commercial aquacultural shellfish in the north of China and the related breeding research work has also been developed. In 2003, a rare color variant was discovered in the natural population. This adductor muscle tissue of this variant was orange as opposed to the common white. Orange variants have not been reported before in scallops. The color of adductor muscle can be steadily inherited and it can be used for breeding. The growth rate of the Yesso scallops with orange adductor muscle was faster than the control group significantly. The new variety of the Yesso scallop was named"Hai da jin bei". The former research showed that the adductor muscle turned to orange because of the deposition of the carotenoid, however, the mechanism of the deposition is yet to be described.Differentially expressed genes in adductor muscle of Yesso scallop (Patinopecten yessoensis) were isolated by using suppression subtractive hybridization (SSH) technique. In the forward subtracted library, the cDNA of orange adductor muscle was used as tester and the cDNA of white adductor muscle was used as driver. In the reverse subtracted library, the cDNA of white adductor muscle was used as tester and the cDNA of orange adductor muscle was used as driver. The cDNA fragments differentially expressed in both subtracted library were sequenced by using 454 sequencing technique. In the forward subtracted library, 50 contigs were obtained from 2640 sequences, which include genes such as tight junction protein, ankyrin, manganese-superoxide dismutase, Phosphogluconate mutase C and ferritin. The function of isolated genes in the forward subtracted library relates to osmoregulation, cell connection, muscle movement and elimination of activated oxygen. In the reverse subtracted library, 187 contigs were obtained from 2496 sequences, which include genes such as polyubiquitin, PDZ structural domain protein and solute carrier family 25. The function of isolated genes in the reverse subtracted library relates to degradation of protein, signal transduction and transcription.Combined with the 454 sequencing results of Yesso scallop transcriptome, there are a lot of differentially expressed genes between both kinds of Yesso scallops. Based on the quantity level and function of genes, we choose three scavenger receptor genes such as SRB1, SRF2 and SRCR as candidate genes. As followed are two reasons: first, based on the significant difference test result, the sequence quantities of the scavenger receptors are significantly different between both kinds of Yesso scallops; second, researchers discovered that scavenger receptor played an important role in mediating the cellular uptake of carotenoids in Drosophila. Compared with other candidate genes, such as ferritin, polyubiquitin, the mediating function of scavenger receptor is more obviously. The analysis of quantitative expression of scavenger receptor genes in all tissues of Yesso scallop was carried out, the results revealed that the scavenger receptors may play a key role in mediating the cellular uptake of carotenoids in Yesso scallops.The results provided preliminary foundation for exploring the pathway of carotenoids accumulation.