A novel c.-274C>G polymorphism in bovine SIRT1 gene contributes to diminished promoter activity and is associated with increased body size.

SIRT1, a mammalian homologue for yeast silent information regulator 2 (SIR2), is a NAD(+) -dependent deacetylase that belongs to the class III histone deacetylases. It plays an important role in diverse cellular processes, including stress resistance, mitochondrial function, suppression of inflammation and DNA repair. In this study, we screened and identified a novel polymorphism (c.-274C>G) in the SIRT1 promoter region. In silico prediction reveals that this SNP is in the core of cell cycle-dependent element (CDE)-binding motif. Interestingly, the G allele abolished a CDE-binding site, which suggested its functional significance. In the luciferase assay system, we found that the G allele-containing construct displayed a strikingly lower promoter activity compared with the C allele, which may downregulate SIRT1 expression levels. Additionally, we observed a significant association between the c.-274C>G polymorphism and growth traits in Nanyang cattle, suggesting that anomalous transcription factor-based repression of SIRT1 may increase bovine fat mass and body size.

Genotype and haplotype analysis of the AZGP1 gene in cattle.

Zinc-a2-glycoprotien (AZGP1) involved in lipid metabolism and associated with adipose tissue atrophy in cachexia. And it also related to sperm motility and in turn fertilization. To ascertain whether there were mutations in the bovine AZGP1 gene, this study investigated variation of the AZGP1 gene through PCR-SSCP and sequencing. Four missense mutations were identified in 649 cattle from six independent populations. Haplotype frequencies and linkage disequilibrium (LD) coefficients of these SNPs in three Chinese indigenous cattle breeds were analyzed. One LD block was found in three cattle breeds. The statistical analyses indicated that AC genotype of Z4 locus was associated with the high body weight, body length and chest girth in Jiaxian cattle breed (P < 0.05). Our results provided evidence that polymorphisms in the AZGP1 gene were associated with growth traits, and may be used for marker-assisted selection and management in cattle breeding program.

[Molecular genetic characteristic of bovine HTR1B gene].

The aim of the present study was to identify and characterize polymorphisms within the coding region and the 3' flanking region of the bovine serotonin receptor 1B gene among different cattle breeds. Four DNA fragments were amplified by polymerase chain reaction and then used for polymorphism identification by SSCP. The fragments showing different SSCP patterns were sequenced. And a total of six SNPs (G205T, C507T, C546G, C744T, G816A and G942A) were detected. The SNPs were at Hardy-Weinberg equilibrium except C507T and C546G in all genetic population. The frequencies of allele 205T of Holstein were much higher than that of the other six beef cattle populations. Almost the PIC of all SNPs were not more than 0.10 except that of G205T in Holstein cows, which indicated the bovine HTR1B gene was conserved.

[Polymorphism Analysis of the CSN1S2 Gene Digested.].

PCR-RFLP was applied to analyze the polymorphism of CSN1S2 gene in 170 goats that comprised of five goat breeds, namely Xinong Saanen dairy goat, Guanzhong dairy goat, Shaannan white goat, Angora goat and Boer goat. A 310 bp -long PCR product was digested with Alw26I and demonstrated polymorphism in five goat populations that were all at Hardy-Weinberg equilibrium (P>0.05). For Xinong Saanen dairy goat, Guanzhong dairy goat, Shaannan white goat, Angora goat and Boer goat, gene heterozygosity/effective allele gene number/Shaanon information entropy /Polymorphism information content were 0.1589/1.1889/0.2955/0.1463, 0.4114/1.6981/0.6017/0.5171, 0.1653/1.1980/0.3046/0.1516, 0646/1.0691/0.1463/ 0.0625, 0.0541/1.0572/0.1270/ 0.0526, respectively. According to the heredity diversity indexes described above of the five goat breeds, Guanzhong dairy goat had the most abundant heredity diversity and showed high polymorphism, and Xinong Saanen dairy goat and Shaannan white goat were inferior, while Angora goat and Boer goat had the lowest genetic variability.

[Polymorphisms of insulin-like growth factor binding protein 3 gene and its associations with several carcass traits in Qinchuan cattle].

DNA samples from 60 Qinchuan cattle (Bos taurus) were analyzed with PCR-RFLPs and sequencing for insulin-like growth factor binding protein 3 (IGFBP3) gene. Fragments of 651 bp were amplified with two primers and the products of PCR were digested with restriction endonuclease HaeIII. The produced fragments showed three genotypes, namely AA,AB and BB after electrophoresis. Frequencies of the genotype AA,AB,BB and allele A,B were 0.7,0.28,0.02,and 0.84,0.16,respectively. Sequence analysis showed that a transversion of C-->A at 299 nt resulted in loss of the cleaved site of restriction endonuclease HaeIII and produced this polymorphism. This polymorphic locus of IGFBP3 gene was at Hardy-Weinberg equilibrium (P>0.05). The genotypes of AA,AB,BB slightly affected several slaughter and carcass traits of Qinchuan cattle. Dressing percentage,net meat percentage, striplion percentage, tenderloin percentage, ribeye percentage and tender shoulder percentage were decreased with the genotypes of AA,AB and BB in Qinchuan cattle, but it was not significant (P>0.05). Average ribeye area in individuals of AA genotype was significantly higher than that in individuals of BB genotype (P<0.05), and beef fat content in individuals of genotype AB and BB was significantly higher than that in individuals of AA genotype (P<0.01).