Deng Xuemei

The single nucleotide polymorphisms of chicken melanocortin-4 receptor (MC4R) gene and their association analysis with carcass traits

Mutations of the melanocortin-4 receptor (MC4R) gene are associated with the appetite, obesity and growth in pig, mice and human. But little is known about the function of chicken MC4R gene. In this study, F2 chicken resource population derived from broilers crossing to Silky was screened for the polymorphisms of the MC4R gene using PCR-single strand conformation polymorphism (PCR-SSCP) and DNA sequencing methods. Four single nucleotide polymorphisms (SNPs) sites were found. The mutation (C→T) in the 5′ regulation region of chicken MC4R gene results in one more NF-E2 and cap transcription factor binding sites in the mutation allele than in the wild allele. One missense mutation (G→A) occurs in the coding region (61nt), which changes the glycine to arginine. Moreover, in the coding region there are 2 synonymous mutations, one G→T mutation at 315nt and one C→T mutation at 336nt. Least square analysis of the SNPs and carcass traits showed that BB, DD and FF genotypes are significantly associated with body weight, carcass weight (or half carcass weight), and leg muscle weight (P<0.05 or P<0.01). But no significant association between the genotypes and abdominal fat weight is found. The results present the evidence that the chicken MC4R gene can be selected as the major candidate gene for the carcass traits such as body weight and growth.

Single nucleotide polymorphisms in chicken lmbr1 gene were associated with chicken growth and carcass traits

Lmbr1 is the key candidate gene controlling vertebrate limb development, but its effects on animal growth and carcass traits have never been reported. In this experiment, lmbr1 was taken as the candidate gene affecting chicken growth and carcass traits. T/C and G/A mutations located in exon 16 and one A/C mutation located in intron 5 of chicken lmbr1 were detected from Silky, White Plymouth Rock broilers and their F2 crossing chickens by PCR-SSCP and sequencing methods. The analysis of variance (ANOVA) results suggests that T/C polymorphism of exon 16 had significant association with eviscerated yield rate (EYR), gizzard rate (GR), shank and claw rate (SCR) and shank girth (SG); A/C polymorphism of intron 5 was significantly associated with SCR, liver rate and head-neck weight (HNW), while both sites had no significant association with other growth and carcass traits. These results demonstrate that lmbr1 gene could be a genetic locus or linked to a major gene significantly affecting these growth and carcass traits in chicken.

An association between tyrosinase gene single nucleotide polymorphisms and melanin distribution in chicken

Tyrosinase (TYR) is a key enzyme of melanin biosynthesis. Single-strand conformation polymorphism (SSCP) analysis was applied to detect the single nucleotide polymorphisms (SNPs) in the upstream regulating region from -641 to -2125 bp of the TYR gene. Three SNPs were found in this region. Correlations were obtained between genotypes of the SNP sites and pigment traits in chicken parental and F 2 generations of the Chinese Agricultural University (CAU) resource population. The chi-square test indicated that these mutations were significantly related to shank and body skin colours.