Study On The Association Of TYR And TYRP1with Plumage Color In Korean Quails

The Korean quails are widely distributed in China and have intricate colorpolymorphism. Plumage color is an important economic trait, which plays a crucialrole in determining breed purity and phylogenesis. Tyrosinase (TYR) and Tyrosinase-related protein1(TYRP1) play crucial roles in determining the plumage color of birds.In this paper, we aimed to characterize the relationship of TYR and TYRP1genes withplumage colors in Korean quails. The results were as follows:The complete coding region of Korean quails TYR gene encoded a protein of529amino acids and this protein was named as tyrosinase. Its molecular weight was60078.9Da and theoretical pI was5.94. Moreover, the total number of negativelycharged residues was54and the total number of positively charged residues was46.The instability index (II) was computed to be58.15and this classifies the protein asunstable. Furthermore, amino acid sequences alignment showed that there is highidentity between the Korean quails TYR gene with these of poultry (96%), mammals(73.9%~70.9%), amphibians (67.9%) and fish (60.7%).The coding region of Korean quails TYRP1gene encoded a protein of391aminoacids. Its molecular weight was44727.8Da and theoretical pI was9.22. Moreover, thetotal number of negatively charged residues was20and the total number of positivelycharged residues was32. The instability index (II) was computed to be39.17and thisclassifies the protein as stable. Furthermore, amino acid sequences alignment showedthat there is high identity between the Korean quails TYRP1gene with these of poultry(97.8%~93.5%), mammals (73.6%~68.4%), amphibians (64.7%~64.4%) and fish(58.3%).The expression of TYR and TYRP1produces significant differences between thethree kinds of plumage color (black, maroon and white plumage) Korean quails byquantitative RT-PCR (qRT-PCR). The expression level of TYR mRNA in skin tissueswas higher in maroon Korean quails than that in white Korean quails, and was significantly higher in black Korean quails. On the other hand, the expression level ofTYRP1mRNA in skin tissues was lower in maroon Korean quails than that in whiteKorean quails, and was significantly lower in black Korean quails.The SNPs of the TYR and TYRP1genes were searched by cDNA sequencing andPCR-SSCP in three plumage color Korean quails. Two SNPs were found in TYRP1gene. The first SNP was a base substitution (T/C) at367bp of coding region, whichchanged a leucine to a serine in protein sequence. Genotyping of84Korean quails wastested by PCR-SSCP and three kinds of genotypes (AA, AB, and BB) were found inthis population. The second SNP was also a base substitution (C/T) at1,153bp ofcoding region, which changed a threonine to a isoleucine in the protein sequence.Genotyping of61Korean quails were tested by the same method and three genotypes(AA, AB, and BB) were found in this population. Compared with TYRP1gene, nomutation was found in TYR gene by cDNA sequencing.The pcDNA3.1(+)-TYR was transfected into quail embryo, and the expressionlevel of the gene was detected by qRT-PCR. The results showed that the expressionlevel of TYR was higher in the9thday/12thday pcDNA3.1(+)-TYR groups than that inthe9thday/12thday control groups, whereas the expression level of TYRP1was higherin the9thday/12thday control groups than that in the9thday/12thday pcDNA3.1(+)-TYR groups. Moreover, the expression level of MC1R was higher in the9thday/12thday pcDNA3.1(+)-TYR groups than that in the9thday/12thday control groups,whereas the expression level of ASIP was higher in the9thday/12thday control groupsthan that in the9thday/12thday pcDNA3.1(+)-TYR groups. It was interesting that theplumage color of quail in pcDNA3.1(+)-TYR groups were significantly darker.This study suggested that the melanic plumage color in Korean quails may beassociated with either increased production of TYR or decreased production of TYRP1.Two SNPs (367T/C and1153C/T) were found in the coding region of TYRP1gene,but had no significant association with plumage phenotype in Korean quails. Inaddition, the TYR gene sequences are highly conserved in either Korean quails orchicken and the TYRP1gene sequences are highly conserved in either Korean quailsor Japanese quails.