Preliminary Study On Correlation Of Scarb1 To Body Color Phenotype Of Oujiang Color Common Carp

Body color is an important biological trait of organisms.It plays an important role in biological activities such as camouflage,survival,courtship,reproduction and reproduction.Fish body color is one of the most abundant phenotypic traits and important germplasm characteristics.It is a classic material to study the genetic law and determination basis of traits.Although a large number of studies on fish body color have been carried out all the world and more than 200 genes that may affect fish body color have been reported,there are few reports on the genes that play a decisive role in fish body color variation.Previous studies in the laboratory found that carotenoids are the main pigment type of the body color of Oujiang color common carp,and the carotenoid absorption and transport related gene Scarb1 plays an important role in the body color control of Oujiang color common carp,but there are few studies on this gene so far.In order to better understand the role of Scarb1 gene in the body color determination of Oujiang color common carp and its influence on the animal body color phenotype,this study took Oujiang color common carp as the research object to study the role of Scarb1in the body color control.The specific results are as follows:1.Observation of pigment cells and expression analysis of Scarb1 gene in Oujiang color common carpThe body surface of fish generally contains many types of pigmented cells,and different combinations of pigmented cells and their arrangements constitute the pentachromatic body color of the fish body surface.In this chapter,we determined that the major groups of pigmented cells,including xanthophores,erythrophores,melanocytes,and iridocystes,are contained on the scales of the Oujiang color common carp in the wild-type and that the types of pigmented cells contained on the scales of the different body colors vary.Subsequently,ELISA enzyme-linked immunoreactivity assays were performed to determine the total carotenoid content in various tissues of the four body coloration of Oujiang colored common carp,and the results showed that the differences in carotenoid contents among individual tissues of these four wild-type Oujiang color common carp were not significant and mainly showed significant differences between whole white and other body colored skin.Expression analysis of the gut,blood,eye,skin,muscle,and fin girdle of four species of Oujiang color common carp found the highest expression in the gut of four colorations of Oujiang color common carp,indicating that this gene is important for carotenoid absorption in the gut.At the same time,Scarb1expression was relatively high in eyes and skin of RB and WB,indicating that Scarb1may be associated with the melanin pathway or melanocyte formation.2.Comparison of coloration related traits between wild-type and Scarb1 knockout type of Oujiang color common carpIn this study,pigment cells and carotenoid contents of scales from individuals with the WR（whole red）,WW（whole white）coloration of Oujiang color common carp were observed and measured in both the gene edited mutant F₁ and the wild fish.The results showed that the scales of the wild-type WR Oujiang color common carp contained xanthophore,erythrophore and iridescent cells,whereas the scales of the mutant type WR contained only xanthophore and iridocyste but no erythrophore.Both scale pigmented cells of wild-type and mutant type WW Oujiang color common carp were iridocyste with no xanthophore and erythrophore.Carotenoids in the gut,plasma,muscle,and skin of wild-type WR individuals were all significantly higher（P<0.05）than those of mutant type WR individuals;Carotenoid contents in the gut,muscle,and fin strips of wild-type WW were also significantly higher（P<0.05）than those of mutant type WW.The present study indicate that knockout of Scarb1 affects the production of red pigment cells on the body surface of Oujiang color common carp,which plays a role in the control of red and white coloration in the Oujiang color common carp.3.Correlation analysis between SNP markers in 5’UTR of Scarb1 gene and body color in Oujiang color common carpIn a previous study,a total of 208 SNP loci were detected in the Scarb1 gene of Oujiang color common carp,and three SNPs in the 5’UTR was observed and one SNP is consistent with a significant recessive relationship between red and white body color.After amplification and sequence alignment of DNA from 203 randomly selected wild-type Oujiang color common carp with white or red body color,all three SNP loci were found to be homozygous genotypes（AA/CC/CC）in whole white（WW）,whereas four heterozygous genotypes（AG/CC/CC,AG/CC/CT,AG/CT/CC,AG/CT/CT）were found in whole red（WR）in addition to a homozygous genotype（AA/CC/CC）.However,three SNPs were not found to be associated with red and white body color in Oujiang color common carp.