Polymorphisns In The3’UTR Region Of Chicken FADS2Gene And Their Association With Economic Traits

Fatty acid delta-6-desaturase (FADS2) is the rate-limiting enzyme in the formation ofomega-6and omega-3highly unsaturated fatty acids (HUFAs). The protein encodedby this gene is a member of the fatty acid desaturase (FADS) gene family. HUFAs areimportant for brain development, inflammatory processes and flavor of meat.Thecoding sequence of Δ-6desaturase included12exons, being similar to the human, butthe3’ untranslated region is different from that in human. There is one intron insertamong12and13exon. and3’UTR regions are involved in various biologicalprocesses such as post transcriptional regulatory pathways, stability, and translationalefficiency.No reports on the genetic diversity analysis have been found so far in thestudies of chicken FADS2gene,thus the present study took this gene as the target genefor the chicken economic traits.First, a DNA pool was build using DNA sample from72chicken of F2resource population of Gushi chicken crossed with Anka broiler,andsequenced to screen the putative SNPs occurred in the3’UTR region. Through thebioinformatics analysis, one microsatellite site was found in the3’ UTR region ofchicken FADS2gene.Then after, the PCR-RFLP and PCR-SSCP were empolyed togenotype the totle849chickens at5SNPs (A240G, G322C, G840A,T1167C and T192C)and one microsatellite sites.The main result are as follows:(1)A total25polymorphic loci were pick out for the first time in the study of this genefrom a DNA pool was build using DNA samples from72chickens of F2resourcepopulation of Gushi chicken crossed with Anka broiler. Through bioinformaticsanalysis, one microsatellite site was certified in the of3’ UTR region of chickenFADS2gene.(2)The genotyping for the5variations found reveled that each of these loci occurredin the population studied with the full3genotypes. Of4sites,A240G was dominatedby the allele G and genotype AG,with an allele frequency and genotype frequency of0.68and0.56, respectively.The further examination showed that the polymorphicinformation content(PIC),heterozygosity (He)and effective allele number(Ne) of0.34,0.44and1.77in the population of interest,respectively.At the locus G322C, thedominant allele and genotype were C (0.68) and GC(0.56), respectively.Whereas,thePIC, He and Ne of this locus were0.34,0.43and1.76, respectively.For another locusT840A, the dominat allele and genotype were A (0.68) and AA(0.46),,and the PIC,He and Ne were0.34,0.44and1.77, respectively. Another locus T1167C, the allele and genotype were dominated by C(0.58) and TC(0.63), and the PIC, He and Ne were0.37,0.49and1.95, respectively. At the locus T192C, the dominat allele and genotypewere C(0.66) and TC(0.51), and the PIC, He and Ne of this site were0.35,0.49and1.81, respectively.(3) The one microsatellite present in the3’UTR had been analyzed by PAGEelectrophoresis for polymorphism. The genotyping results found reveled that the locusoccurred with the2genotypes in the population studied. At the site, the dominat alleleand genotype were A (0.96and AA(0.91), and the PIC, He and Ne were0.08,0.08and1.09, respectively.(4) The subsequent association analysis of these5locis and1microsatellite with thecorresponding production traits demonstrated that the locus G322C was absolutelyunrelated to the all characters examined. However, the SNP A240G showedsiginficant correlation with some traits,such as Liver weight, γ-GlutamylTranspeptidans, Alkaline Ph-osphatase, Lactic Dehydrogenase, C14:0, C17:0andC22:3.For the locus T840A,the homozygote AA and TT were lower than heterozygoteTA in the Liver weight and Leg shear force. For the locus T1167C,the homozygoteCC was higher than heterozygote TC and homozygote TT in the Carcass weight,Liver weight, Heart weight and Breast shear force. For the locus T192C, thehomozygote CC was higher than heterozygote TC and homozygote TT in the Heartweight, Spleen weight,Low Density Lipoprotein and C20:1, the homozygote TT washigher than heterozygote TC and homozygote CC in the Breast shear force,andheterozygote TC was higher than homozygote TT and CC in Leg shear force. onemicrosatellite sites, the homozygote AA was higher than heterozygote AB in the Heartweight and Breast muscle weight.Therefore, it can be reasonably concluded as follows:(1) There are total25SNP and one microsatellite sites in the3’UTR region of chickenFADS2were found by sequenced and bioinformatics analysis. Thus,the3’UTR regionof chicken FADS2is rich in genetic variation, implying a great roal in variousbiological processes such as post transcriptional regulatory pathways, stability andtranslational efficiency.(2) There polymorphism sites were significantly related with some economic traits ofchicken,they may be worked through the change of mRNA stability anddecomposition rate and give further influence on the gene expression. Thesepolymorphism sites can be expected to develop possible molecular markers for improve the flavor of chicken meat and sellection of corresponding traits in thechicken breeding. Further investigations are required for detecting the underlyingmachinim of these polymorphism site on the gene function.