SNPs In Chicken Let-7b Precursor Region And Its Association With Growth And Meat Traits

miRNAs are a class of endogenous non-coding functional RNAs with about 22 nucleotides,which regulate gene expression by fully complementary or incomplete complementary pairing with the mRNA 3' untranslated region of the target gene.Each miRNA may have several target genes.Single Nucleotide polymorphisms(SNPs),located on the sequence of miRNA gene,can change pri-miRNA processing process or mature miRNA selection of target gene,thus affecting the function of miRNA.So it is very important to identify and reveal the function of miRNA SNP.The main purpose of this study is to investigate the SNP located in let-7b precursor region,and do the correlation analysis with growth carcass,meat quality and other traits of chicken.The biological function of let-7b and the effect of SNP on let-7b function were revealed.In this study,the precursor region of chicken let-7b was screened by bioinformatics and sequencing,and the whole sib family of Xinghua Chicken and Recessive White Rock F2 generation in the key Laboratory of Molecular breeding was used as the research material.The SNP of let-7b precursor gene was identified by direct DNA sequencing and genotyped,and the function of SNP was preliminarily revealed by correlation analysis with economic traits such as growth,carcass and meat quality of the resource group.Let-7b overexpression vectors of different haplotypes of let-7b were constructed and transfected into chicken primary myoblasts.The effects of let-7b overexpression vectors containing different haplotypes on the expression of let-7b were detected by fluorescence quantitative PCR.The main results of this study were as follows:1.The sequence of let-7b precursor region was obtained and four mutation sites were detected by pooling sequence,g.270G>A?g.526G>A?g.678T>C?g.710G>C.2.A great deal of data of carcass growth and meat quality traits of Xinghua ×Recessive White Rock F2 generation were obtained by feeding experiment,and the correlation analysis was carried out with the mutation site sequencing data and the growth carcass and meat quality traits.There was significant correlation between g.270 G > A and live weight,wing weight,crude protein content of leg muscle(P <0.05)and the ratio of leg to chest(P < 0.01).g.526 G > A)with leg muscle weight(P <0.05)and leg / chest ratio(P < 0.05).There was a significant correlation between the tibia length of leg muscle PH6 days and the tibial diameter of 77 days(P < 0.01).There was a significant correlation between P < 0.01 and 77 days(P < 0.01).3.Five recombinant plasmids of different haplotypes were obtained and transfected into chicken primary myoblasts.The expression of let-7b matured bodies with different haplotypes was measured.After AGCC haplotype transfection,the relative expression of let-7b mature sequence was 2.362;AACC haplotype was 3.188;GATC haplotype was 3.649;GACG haplotype was 3.052;let-7b haplotype was2.977;pcDNA3.1 empty vector was 1.054.