Selecting Milk Quality Traits Relative Genes Of Dairy Cows With Gene-Chip

Milk quality characteristics are considered as the crucial economic traits of the dairy cows in production, which is a typical quantity characteristic controlled by minorgene, including protein yield, protein rates, fat yield, and fat rates, and so on. Milk quality characteristics have direct impact on the nutrition, sapour of the milk and the economic benefit of dairy production. While the quality of milk would fluctuate within a certain range due to physiological and genetic factors. Basing on the market demand and human nutrition, it is very urgent to improve the milk quality by functional genes and functional SNPs.In this experiment,60Chinese Holstein cows from Jihuan Yikang Dairy Production were chosen and divided into4groups, dry period, earlier lactating period, middle lactating period and late lactating period. Tail vein blood genome expression profiling of different lactation Chinese Holstein cows was analyzed by Affymetrix Microarray. the JAK-STAT pathway was chosen as the study target for further analysis from the results of KEGG pathway of2times up or down differential expression genes. The2times up or down differential expression genes in JAK-STAT pathway were confirmed and candidate genes related lactation traits were initially identified. In addition, STAT1full length mRNA sequences of Chinese Holstein cow was cloned. The SNPs in STAT13’-UTR and STAT4intron20were also preliminarily assessed for marker-assisted breeding in the Chinese Holstein cows.Results suggested:(1)The results of the Chinese Holstein cows Affymetrix Microarray showed:the gene quantity of lactating period was more than that of dry period. Gene quantity and rate of the different periods were earlier lactating period13091/54.30%, middle lactating period15007/62.20%, late lactating period15241/63.20%and dry period4762/19.70%respectively. In different periods, the largest difference appeared between middle lactating period and dry period, which there were14472-Fold-up-change genes and18062-Fold-down-change genes. The smallest difference appeared between middle lactating period and late lactating period, which there were162-Fold-up-change genes and262-Fold-down-change genes.(2)GO analysis of2-Fold-up-change genes declared, differential expression genes in biological process involved cellular process, physiological process, metabolism, biological regulation, regulation of biological process, developmental process, localization, establishment of localization, response to stimulus, positive regulation of biological process, immune system process, negative regulation of biological process and multicellular organismal process; differential expression genes in Cellular component involved cell, cell part, ganelle, organelle part and macromolecular complex; differential expression genes in Molecular function involved catalytic activity, molecular transducer activity, transporter activity and binding.(3)The JAK-STAT pathway was chosen as the study target for further analysis from the results of KEGG pathway of2times up or down differential expression genes. There are262-Fold-up-change or2-Fold-down-change differential expression genes including AKT1, AKT2, STAT1, STAT3, and so on. Differential expression genes involved protein binding, receptor activity, transcription factor activity, serine/threonine protein kinase activity, protein kinase activity and other molecular features.(4)STAT1full length mRNA sequences of Chinese Holstein cow was successfully cloned, which5’-UTR length was286bp(1～286bp); open reading frame was2250bp(287-2536bp), coding749amine acid;3’-UTR length was1742bp(287-2536bp). The results of sequence analysis demonstrated the tailing signal AAUAA of mRNA in animal appeared at927bp,1548bp and1688bp after termination codon, and polyA tail appeared18bp behind the third tailing signal. ATTTA sequence appears at308bp,812bp and1486bp after termination codon. Meanwhile, different mRNA alternation splicing in5’-UTR and3’-UTR were found.(5)Bioinformatics Analysis result suggested Chinese Holstein cow STAT1protein was hydrophilia protein, which Molecular Weight was87098.6D and PI was5.80. Multiple alignment of mammalian STAT1protein showed, Chinese Holstein cow STAT1protein sequence had99.60%identity with the sheep STAT1protein, rhesus and dog96.40%, human95.87%, gorilla95,73%, pig95.64%, wooly monkey95,47%, mice91.32%, rabbit90.25%, and rat88.25%. In addition, the conservative structural domains of STATs family were also found in Chinese Holstein cow STAT1protein, including STAT_int, STAT_alpha, STAT_bin, SH2and STAT_TAZ2.And there were multiple phosphorylation sites of serine, threonine and tyrosine.(6)SNPs in STAT13’UTR and STAT4intron20were separately amplified from gDNA obtained from Chinese Holstein cows. The results decleared, no polymorphism was detected within STAT13’UTR in groups of Chinese Holstein; a moderately polymorphic SNP was detected within STAT4intron20. Generalized Linear Models analysis between genotypes(AA, AB and BB) and milk production traits indicated that there were no significant differences among three genotypes on305days milk yield,305days protein yield,305days fat yield, while the tendency of BB>AB>AA was found.