Two novel polymorphisms of bovine SIRT2 gene are associated with higher body weight in Nanyang cattle.

Identification of polymorphisms associated with economic traits is important for successful marker-assisted selection in cattle breeding. The family of mammalian sirtuin regulates many biological functions, such as life span extension and energy metabolism. SIRT2, a most abundant sirtuin in adipocytes, acts as a crucial regulator of adipogenic differentiation and plays a key role in controlling adipose tissue function and mass. Here we investigated single nucleotide polymorphisms (SNPs) of bovine SIRT2 in 1226 cattle from five breeds and further evaluated the effects of identified SNPs on economically important traits of Nanyang cattle. Our results revealed four novel SNPs in bovine SIRT2, one was located in intronic region and the other three were synonymous mutations. Linkage disequilibrium and haplotype analyses based on the identified SNPs showed obvious difference between crossbred breed and the other four beef breeds. Association analyses demonstrated that SNPs g.17333C > T and g.17578A > G have a significantly effect on 18-months-old body weight of Nanyang population. Animals with combined genotype TTGG at the above two loci exhibited especially higher body weight. Our data for the first time demonstrated that polymorphisms in bovine SIRT2 are associated with economic traits of Nanyang cattle, which will be helpful for future cattle selection practices.

A critical functional missense mutation (H173R) in the bovine PROP1 gene significantly affects growth traits in cattle.

The PROP1 protein, encoded by the prophet of Pit-1 (PROP1) gene, exhibits both DNA-binding and transcriptional activation abilities. Its expression leads to the ontogenesis of growth hormone (GH), prolactin (PRL), thyroid-stimulating hormone (TSH), and pituitary hormone. The missense mutation H173R in PROP1 may result in deficiencies of GH, PRL, TSH, and Pit-1, thereby affecting growth traits. The objective of this study was to characterize the H173R mutation within the PROP1 gene and examine its associations with growth traits in cattle. Accordingly, the H173R mutation was genotyped in 1207 cows belonging to five Chinese native breeds. Three genotypes were identified among the specimens, with genotype AA being the major one. Consequently, the "G" allele was the minor allele. Association testing revealed that the H173R mutation was significantly associated with body weight, average daily weight gain and physical parameters in the analyzed breeds. Interestingly, the cows with genotype AG and/or AA had superior growth traits compared with those expressing the GG genotype, in all tested breeds. These findings revealed that the "A" allele had positive effects on growth traits, which was consistent with the increasing binding ability and enhanced activation capacity associated with the bovine isoform PROP1-173H, representing the "A" allele. Therefore, the H173R mutation can be considered as a DNA marker for selecting individuals with superior growth traits, thereby contributing to research on breeding and genetics in the beef industry.

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.

A dual color fluorescent reporter system for the real time detection of promoter activity.

Understanding the mechanisms controlling transcription of a gene requires the identification and characterization of its cis-acting regulatory elements. A highly useful approach to the identification and characterization of cis-acting elements has been the systematic coupling of genomic fragments to reporter constructs, so called "promoter bashing". The expression from such reporters must be normalized for differences in transient transfection efficiency between cells and replicates. A novel dual color fluorescent reporter system to assay the promoter activity of a genomic DNA fragment of interest was established by cloning a Discosoma red fluorescent protein gene and a green fluorescent protein gene into a single vector, giving a system in which the ratio between red and green fluorescence is proportional to promoter activity. This system allows real time quantitative monitoring of promoter activity. We validated this approach by assaying the cis-acting regulatory potential of the peroxisome proliferators-activated receptor gamma2 gene.

Analysis of genetic variability at codon 42 within caprine prion protein gene in relation to production traits in Chinese domestic breeds.

In this study, genetic variability at codon 42 within prion protein (PRNP) gene and its associations with production traits were investigated in 2002 goats from four Chinese domestic breeds. The frequencies of allele "A" ranged from 0.353 to 0.562 in analyzed goat breeds with Hardy-Weinberg equilibrium (P > 0.05) except Xinong Sannen (XNSN) dairy breed. The establishment of relationships between different genotypes and growth traits was performed in Inner Mongolia white Cashmere (IMWC) breed and revealed an association of the polymorphism with body weight at 7-year-old goats (P = 0.033). The individuals with genotype GG showed heavier body weight than those with genotype AA. Moreover, association analysis detected two significant associations between different genotypes and cashmere yield and fiber length in IMWC breed (P = 0.009, P = 0.048, respectively). In addition, three significant associations of different genotypes with density of milk (a.m. and p.m.), solids-not-fat of milk (P = 0.013, P = 0.009 and P = 0.002), respectively, were found in XNSN breed. Genotype GG had better milk quality than others. These findings suggested that the polymorphism of codon 42 within PRNP was a useful DNA marker for eliminating or selecting excellent individuals in relation to production traits in marker-assist selection breeding of goat.

Associations of polymorphism within the GHSR gene with growth traits in Nanyang cattle.

GH secretagogue receptor (ghrelin receptor, GHSR) is known to be involved in the control of GH release by mediating the strong stimulatory effect of the endogenous ligand, ghrelin, on GH secretion. Associations between the GHSR gene polymorphism and the growth traits were revealed in Nanyang cattle. The mutations at nt456(G > A) and nt667(C > T) were complete linkage and located in exon 1 of the coding region of the GHSR gene. Least squares analysis revealed a significant statistical effect (P < 0.05) of the GHSR gene different genotypes on body weight and average daily gain at 6 months of age in Nanyang cattle. Individuals with GHSR-MM genotype showed higher body weight and average daily gain than individuals with GHSR-MN genotype.

[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).