奶牛产奶性状与乳房炎相关基因CpG含量及分布特征的比较分析

DNA甲基化是表观遗传学的重要组成部分,基因启动子区及第一外显子区的CpG甲基化通常抑制该基因的表达,而去甲基化则促进基因表达。已有的研究发现荷斯坦牛的乳房炎指标SCC(Somatic cell count)与产奶量呈较强负相关。文章分析并比较了这两类性状的相关基因的启动子区、第一外显子、下游2 000 bp序列中CpG含量及分布特征。结果表明,乳房炎相关基因的启动子、第一外显子中CpG含量显著低于产奶性状相关基因,而两类性状基因下游2 000 bp序列中CpG含量无显著性差异。另外,文中提出了两个量化基因序列中CpG特征的指标,一个是CpG平均距离,用来衡量序列中的CpG分布;另一个是条件概率p(G|C),用以量化序列中二核苷酸CpG随碱基C出现的可能性,并对两类基因的启动子和第一外显子区域的这两个指标做了统计检验。研究结果对产奶性状与乳房炎相关基因的DNA甲基化调控研究奠定了基础。

奶山羊产奶性状相关基因的筛选与功能研究进展

奶山羊作为乳用品种的山羊,因其具有奶质优良、产奶性能稳定、乳汁营养丰富等特点,逐渐成为畜牧业发展的一大亮点。经过多年的选种选育,我国现已拥有了多个地方奶山羊品种。随着分子育种技术的发展,对于奶山羊产奶性状相关基因的研究越来越多。对奶山羊产奶性状相关基因的研究进展进行综述,以期为奶山羊优秀基因资源的研究、保护和利用提供理论依据。

Identification of SNPs in Bovine SLC27A1 Gene and Its Effects on Milk Production Traits in Chinese Holstein Cattle

[Objective] This study discussed the SNPs of SLC27A1 gene and its relationship with milk production traits in Chinese Holstein Cattle in order to find the SNP site which had significant effect on milk production traits in Chinese Holstein Cattle.[Method] DNA was extracted from the bleed of 48 Chinese Holstein Cattle selected according to phenotypic character and mixed into DNA pool for SNPs detection by polymerase chain reaction-single strand conformation polymorphism（PCR-SSCP）and cloning sequencing.Then different genotypes were detected in other 231 Chinese Holstein Cattle by PCR-RFLP.The association between genotype and production traits was assessed by GLM procedure,SAS version 8.02.[Result] There were T112C in exon3 and G64A loci in 3＇UTR,among them the T112C in exon3 was synonymous mutation.There were 3 genotypes TT,TC and CC in T112C locus and 3 genotypes GG,GA and AA in G64A locus.The population was at Hardy-Weinberg equilibration.Cows with genotype CC had significantly highest milk yield than those with genotype TC（P0.01）,and there were no significant differences among the 3 genotypes on milk protein percent and milk fat percent（P0.05）,but the tendency of CC TC TT on milk protein percent and the tendency of TT TC CC on milk fat percent were showed.There was no significant difference among the 3 genotypes of G64A loci on milk yield,milk protein percent and milk fat percent（P0.05）,but the tendency of GA GG AA on milk yield and the tendency of AA GG GA both on milk protein percent and milk fat percent were showed.[Conclusion] There was certain relation between the T112C locus and milk yield traits;It may improve milk yield to raise the frequency of genotype CC;SLC27A1 gene could be a useful candidate gene in selection program on milk yield traits in Chinese Holstein Cattle,which provided a theoretical basis for the marker-assisted breeding and further study of SLC27A1 gene.

Prevalence of lactase persistent/non-persistent genotypes and milk consumption in a young population in north-west Russia

AIM： TO estimate the prevalence of the lactase non-persistent genotype （C/C-23910） in a northern Russian population in accordance with ethnicity, and to evaluate self-reported milk consumption depending on lactase activity. METHODS： Blood samples for genotyping lactase activity, defining the C/T-13910 variant by polymerase chain reaction, and direct sequencing were taken from 231 medical students of Russian origin aged 17-26 years. We analyzed milk product consumption by questionnaire which was specially designed for the estimation of milk consumption and abdominal complaints. RESULTS： We found that the prevalence of the C/C-13190 genotype in the northern Russian population was 35.6%. The other genotypes nearby C/T-13910 and associated with lactase activity were not present in the study population. The consumption of milk among people with the non-persistent genotype tended to be lower than among the lactose tolerant subjects, but was not statistically significant. CONCLUSION： An investigation of the lactase persistent genotype in a northern Russian population has not been performed before, The genotype did not affect the consumption of milk products in this population which could be explained by low consumption of milk products among the entire study population.

The Detection of STAT1 Gene Influencing Milk Related Traits in Turkish Holstein and Jersey Cows

The main purpose of this study was to detect an association of cytoplasmic signal transducers and activators of transcription-1 （STAT1） with milk production traits in 472 Holstein and 283 Jersey cattle breeds of Turkey. This gene, located on chromosome 2, was chosen due to its role on development of mammary gland. A polymorphism of selected 314 bp allele fragment was detected by the restriction fragment length polymorphism analysis of polymerase chain reaction-amplified fragments （PCR-RFLP） method and also confirmed by DNA sequencing. The association tests were conducted between STAT1 genotypes and some economically important dairy traits. The genotypes for C/T as a single nucleotide polymorphism （SNP） were identified at interval 60 cM to 63 cM. The effects of STAT1 gene on milk production traits were not significant in Holstein cows, although animals with CT genotypes showed fairly close to significant value for the corrected 305 d milk yield. However, Jersey cows with/7＂ genotype were 2.07 kg higher for test-day milk yield （P 〈 0.05）, 0.13 kg for fat yield （P 〈 0.01） and 0.07 kg for protein yield （P 〈 0.05） compared with animals having CC and CT genotypes. Definitely, the further research should be conducted to search this gene intensively with larger samples to identify polymorphism and any association between the economically important traits and genotypic class in Holstein cows. Finally, based on the findings, it was concluded that STATI gene might be used as a potential candidate gene to improve milk yield and milk fat and protein contents in dairy cows breeding programs.