奶牛HSP70基因3'-侧翼区多态性分析及其与生产性能的关系

以160头荷斯坦和娟姗奶牛作为研究对象,分别测定了其在不同温度条件下,直肠温度、呼吸频率、产奶量及乳成分,并进行了统计分析。同时设计引物扩增HSP70基因3’-侧翼区,通过PCR—SSCP技术分析hSPTO基因3’-侧翼区的多态性,并发现一个多态位点。结果表明：扩增片段为292bp,扩增产物有基因多态性,共发现4种基因型,分别为荷斯坦牛的AA（H）型、AB（H）型和娟姗牛的AA（J）刭、AB（J）型。其中B基因可能为抗热应激耩囚,这4种基囚型奶牛个体的生产性能差异不显著（P〉0．05）。     

Association between Sscp Haplotypes at the Bovine Growth Hormone Gene and Milk Protein Percentage

The bovine Growth Hormone gene (bGH) is an attractive candidate gene for milk production in cattle. Single-strand conformation polymorphisms at bGH were identified and used to define haplotype configurations at this gene in the Israeli Holstein dairy cattle population (Bos taurus) and in the parent animals of the International Bovine Reference Family Panel (a collection of B. taurus and B. indicus crosses). B. taurus and B. indicus haplotypes at the bGH gene differed qualitatively, confirming the previously proposed long evolutionary separation of these cattle subraces. Only a small number of bGH haplotypes were present in the Israel Holstein population. One of the haplotypes, apparently of B. indicus origin, was found to have a highly significant positive effect on milk protein percentage. This illustrates the utility of the haplotype approach for uncovering candidate gene involvement in quantitative genetic variation in agricultural populations. The strong effect of an indicine haplotype in a taurine background raises the possibility that indicine alleles at other candidate genes may comprise a genetic resource for improvement of taurine populations. It is proposed that haplotype analysis may be a useful adjunct to measures of genetic distance for evaluating rare breeds with respect to gene conservation.     

Novel SNPs of the Bovine PRLR Gene Associated with Milk Production Traits

The single nucleotide polymorphisms (SNPs) within exon 10 of the prolactin receptor gene (PRLR) were detected in Chinese Holstein cows using polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and DNA sequencing methods, and their genetic effects on milk production traits were evaluated in this study. Two newly detected SNPs (g.9206G→A and g.9681C→T) caused amino acid variations E378K and A536V, respectively, which were then preliminarily predicted at the topological level. Statistical results indicated that the two SNPs were significantly associated with milk yields, and cows with the combined genotype GGCC showed superior milk performance. A putative phosphorylation site was identified at residue 378K ([ST]-×-[RK]), which offers a partial explanation for the associations. These results suggest that the two novel SNPs within exon 10 of the PRLR gene associated with milk production traits are useful genetic markers in a selection program for Holstein dairy cattle.     

利用微卫星进行奶牛数量性状基因位点定位的研究

采用孙女设计法对德国奶牛的３个数量必状－－产奶量、乳脂产量及乳蛋白产量进行了数量性状基因位点的定位研究。实验共有２０个父系半同胞家系的１１３０头种公牛,共测定了３０对染色体上的２２９个微卫星,表型性状的育种值由孙代母牛估计得到。连锁分析采用多重遗传标记回归法,临界Ｆ值由置换实验法计算得到。统计发现在某些染色体上存在着一些显著的ＱＴＬ＇ｓ区域,特别是１４号染色体上某一区域对所有３个产奶性状都有极显著     

草地藏系绵羊乳游离氨基酸质量分数及蛋白遗传多态性研究

用反相高效液相色谱法检测草地藏系绵羊乳游离氨基酸质量分数,用聚丙烯酰胺凝胶电泳法研究乳蛋白组分及其遗传多态性。结果表明:草地藏系绵羊乳中检测到17种游离氨基酸,其中质量分数最高的为Arg;与金堂黑山羊乳比较17种游离氨基酸中,甲硫氨酸的质量分数极显著高于金堂黑山羊(p<0.01),而天冬氨酸、甘氨酸、赖氨酸、谷氨酸、苏氨酸、丙氨酸和缬氨酸的质量分数均显著低于金堂黑山羊(p<0.05),其余9种游离氨基酸质量分数未发现明显差异,但两种羊乳中的必需氨基酸总量基本相同,差异不明显(p>0.05)。草地藏系绵羊乳蛋白组分主要包括α-La、β-Lg、CN、IgG等,CN的相对质量分数约50%~52%;研究还发现4种分子量类型的乳上皮粘蛋白MUC1,分子量分别为214kD、209kD、207kD、205kD;CN、β-Lg均未检测到多态性,说明草地藏系绵羊乳蛋白遗传多态性较为贫乏。     

Genome-Wide Association Study for Wool Production Traits in a Chinese Merino Sheep Population

Genome-wide association studies (GWAS) provide a powerful approach for identifying quantitative trait loci without prior knowledge of location or function. To identify loci associated with wool production traits, we performed a genome-wide association study on a total of 765 Chinese Merino sheep (JunKen type) genotyped with 50 K single nucleotide polymorphisms (SNPs). In the present study, five wool production traits were examined: fiber diameter, fiber diameter coefficient of variation, fineness dispersion, staple length and crimp. We detected 28 genome-wide significant SNPs for fiber diameter, fiber diameter coefficient of variation, fineness dispersion, and crimp trait in the Chinese Merino sheep. About 43% of the significant SNP markers were located within known or predicted genes, including YWHAZ, KRTCAP3, TSPEAR, PIK3R4, KIF16B, PTPN3, GPRC5A, DDX47, TCF9, TPTE2, EPHA5 and NBEA genes. Our results not only confirm the results of previous reports, but also provide a suite of novel SNP markers and candidate genes associated with wool traits. Our findings will be useful for exploring the genetic control of wool traits in sheep.     

Meta-analysis of Genetic Structure and Association of Prolactin Gene with Performance Traits in Dairy Cattle in India

The present meta-analysis was carried to provide the more reliable estimates of gene frequency and association of Rsa 1 generated candidate genotype of prolactin gene within exon-3 with performance traits in 1198 Indian dairy cows using data from 15 published studies. Six genetic models viz., codominant (AA vs. AB, AA vs. BB and AB vs. BB), dominant (AA+AB vs. BB), completely over dominant (AA+BB vs. AB) and recessive (AA vs. AB+BB) were used to obtain standardized mean difference (SMD) between genotypes. Meta-analysis showed that the gene frequency of A allele (156 bp) was 0.60 (95% confidence interval (CI) 0.54, 0.65). In association analysis, cows with AB genotype [SMD?=?0.65, 95% CI 0.00, 1.30] had significantly (P?<?0.05) higher lactation milk yield (LMY) as compared to BB genotype, whereas AA and AB genotypes had similar trend. Likewise, AA?+?AB also had larger effect [SMD?=?2.31, 95% CI 0.21, 4.10] on LMY as compared to BB. Cows with AB genotype had significantly lower age at first calving (AFC) with small effect [SMD (AA vs. AB)?=?1.38, 95% CI 0.06, 2.70] and medium effect [SMD (AB vs. BB)?=????3.83, 95% CI???6.41,???1.24] as compared to cows with AA and BB genotypes, respectively. This finding was confirmed under dominant and completely over dominant models. In case of fat%, AA genotype showed negative effect (SMD?=????0.51, 95% CI???0.84,???0.17) under recessive model. It was concluded that the propagation of allele A is promising to help dairy farmers to improve the genetic quality of their dairy cows.

     

两个位点主基因控制的质量—数量性状的遗传分析

应用极大似然法和EM算法提出了关于两个位点主基因控制的质量．数量性状的遗传分析方法,参照质量性状两位点互作在F_2代的分离比率建立了7种遗传假设及其似然比测验的程序,讨论了应用这一方法时应注意的几个问题．     

Quantitative Trait Loci Analysis for Five Milk Production Traits on Chromosome Six in the Dutch Holstein-Friesian Population

Twenty Dutch Holstein-Friesian families, with a total of 715 sires, were evaluated in a granddaughter experiment design for marker-QTL associations. Five traits--milk, fat and protein yield and fat and protein percent--were analyzed. Across-family analysis was undertaken using multimarker regression principles. One and two QTL models were fitted. Critical values for the test statistic were calculated empirically by permuting the data. Individual trait distributions of permuted test statistics differed and, thus distributions, had to be calculated for each trait. Experimentwise critical values, which account for evaluating marker-QTL associations on all 29 autosomal bovine chromosomes and for five traits, were calculated. A QTL for protein percent was identified in one and two QTL models and was significant at the 1 and 2% level, respectively. Extending the multimarker regression approach to an analysis including two QTL was limited by families not being informative at all markers, which resulted in singularity. Below average heterozygosity for the first and last marker lowered information content for the first and last marker bracket. Highly informative markers at the ends of the mapped chromosome would overcome the decrease in information content in the first and last marker bracket and singularity for the two QTL model.     

Milk Protein Synthesis, Gene Expression, and Hormonal Responsiveness in Primary Cultures of Mammary Cells from Lactating Sheep

A ruminant mammary cell culture that accurately reproduces mammary function in vitro would be a valuable tool in studies of ruminant lactation, With this in mind, we have examined milk protein synthesis and secretion, milk protein mRNA abundance, and hormonal responsiveness in primary cultures of mammary acini from lecturing sheep. α- and β-casein protein synthesis, β-lactoglobulin synthesis, and α-casein, β-casein, and β-lactoglobulin secretion are maintained at high levels for 8 h in culture, but then decline to approximately 25% of maximal rates between 8 and 24 h in culture, whereas synthesis of other proteins remains unaltered. The relative abundance of α-S₁-casein, β-lactoglobulin, and α-lactalbumin mRNAs similarly decline between 8 and 24 h in culture. Extracellular labeled α-casein is increased fourfold in the presence of fetal calf serum (FCS). In total, FCS alters the abundance of 47 of 68 secreted proteins detected by two-dimensional electrophoresis. However, FCS and lactogenic/galactopoietic hormones had no effect on the rate of decline of mammary function and did not promote any regaining of function when present for up to 9 days in culture. These results suggest that providing its limitations are recognized, this primary cell culture system may be useful in studying some aspects of ruminant mammary function in vitro.     

Sequence Variations in the Bovine Growth Hormone Gene Characterized by Single-Strand Conformation Polymorphism (Sscp) Analysis and Their Association with Milk Production Traits in Holsteins

Sequence variations in the bovine growth hormone (GH) gene were investigated by single strand conformation polymorphism (SSCP) analysis of seven amplified fragments covering almost the entire gene (2.7 kb). SSCPs were detected in four of these fragments and a total of six polymorphisms were found in a sample of 128 Holstein bulls. Two polymorphisms, a T->C transition in the third intron (designated GH4.1) and an A->C transversion in the fifth exon (designated GH6.2), were shown to be associated with milk production traits. GH4.1(c)/GH4.1(c) bulls had higher milk yield than GH4.1(c)/GH4.1(t) (P <= 0.005) and GH4.1(t)/GH4.1(t) (P <= 0.0022) bulls. GH4.1(c)/GH4.1(c) bulls had higher kg fat (P <= 0.0076) and protein (P <= 0.0018) than GH4.1(c)/GH4.1(t) bulls. Similar effects on milk production traits with the GH6.2 polymorphism were observed with the GH6.2(a) allele being the favorable allele. The average effects of the gene substitution for GH4.1 and GH6.2 are similar, with +/-300 kg for milk yield, +/-8 kg for fat content and +/-7 kg for protein content per lactation. The positive association of GH4.1(c) and GH6.2(a) with milk production traits may be useful for improving milk performance in dairy cattle.     

西方蜜蜂产浆量的动态遗传研究

应用条件和非条件遗传效应分析方法对3个西方蜜蜂(Apis mellifera L.)品种的蜂群产浆量、台浆量和台基接受率进行了发育遗传研究。结果表明：蜂群产浆量、台浆量在各个时期均存在显著或极显著的基因型方差,台基接受率在大部分时期存在显著或极显著的基因型方差,说明这3个性状主要由遗传因素决定。条件遗传分析发现,在某些无法检测到非条件方差的时期存在显著水平的条件方差,证明在产浆期的不同阶段,3个性状都有基因的新表达。同一性状不同时期的遗传相关分析表明：蜂群产浆量以及台浆量在各个时期均检测到显著或极显著的基因型相关,台基接受率在大多时期存在显著的基因型相关,表明控制产浆量和台浆量早期表现的遗传效应总是以相同的方式调节后期的表现,而台基接受率则不然。成对性状之间的相关研究表明：蜂群产浆量和台浆量之间在各个时期存在显著或极显著的遗传相关,说明2性状基因效应之间的协同作用是一致的,而蜂群产浆量和台基接受率之间在大多时期存在显著的遗传相关,但在一些时期没有相关,2性状之间的基因效应协同作用较差。     

Genetic Analysis on Gene Effects and GE Interaction Effects for Kernel Nutrient Quality Traits of Upland Cotton

1IntroductionCanon~,whichhavehighcontentOfoilandprotein,areanimPOrtantnutrientr~eforfaceandforage.~areanewgenerationresultedfromfertilndionOff~eandmalegarnetes,butmOStOfseednutrientSareprovidedbymat~plantSonwhichseedsbeal.Therefore,seedtTaitS~besdriltaneouslyconchedbyednucleargenes,cytOPhangenes,andmaternalplantnucleargenes.SeeddireCteffectsandmaternaleffeCtshavebendetectedforseedquantitativetraitsinsomecrOPssuChasrapeseed(PleinesandFriedt,1989),andbarley(KaePplerandRasmusson,1991).I…     

Gene-Based Mapping and Pathway Analysis of Metabolic Traits in Dairy Cows

The metabolic adaptation of dairy cows during the transition period has been studied intensively in the last decades. However, until now, only few studies have paid attention to the genetic aspects of this process. Here, we present the results of a gene-based mapping and pathway analysis with the measurements of three key metabolites, (1) non-esterified fatty acids (NEFA), (2) beta-hydroxybutyrate (BHBA) and (3) glucose, characterizing the metabolic adaptability of dairy cows before and after calving. In contrast to the conventional single-marker approach, we identify 99 significant and biologically sensible genes associated with at least one of the considered phenotypes and thus giving evidence for a genetic basis of the metabolic adaptability. Moreover, our results strongly suggest three pathways involved in the metabolism of steroids and lipids are potential candidates for the adaptive regulation of dairy cows in their early lactation. From our perspective, a closer investigation of our findings will lead to a step forward in understanding the variability in the metabolic adaptability of dairy cows in their early lactation.     

A Multiple-SNP Approach for Genome-Wide Association Study of Milk Production Traits in Chinese Holstein Cattle

The multiple-SNP analysis has been studied by many researchers, in which the effects of multiple SNPs are simultaneously estimated and tested in a multiple linear regression. The multiple-SNP association analysis usually has higher power and lower false-positive rate for detecting causative SNP(s) than single marker analysis (SMA). Several methods have been proposed to simultaneously estimate and test multiple SNP effects. In this research, a fast method called MEML (Mixed model based Expectation-Maximization Lasso algorithm) was developed for simultaneously estimate of multiple SNP effects. An improved Lasso prior was assigned to SNP effects which were estimated by searching the maximum joint posterior mode. The residual polygenic effect was included in the model to absorb many tiny SNP effects, which is treated as missing data in our EM algorithm. A series of simulation experiments were conducted to validate the proposed method, and the results showed that compared with SMMA, the new method can dramatically decrease the false-positive rate. The new method was also applied to the 50k SNP-panel dataset for genome-wide association study of milk production traits in Chinese Holstein cattle. Totally, 39 significant SNPs and their nearby 25 genes were found. The number of significant SNPs is remarkably fewer than that by SMMA which found 105 significant SNPs. Among 39 significant SNPs, 8 were also found by SMMA and several well-known QTLs or genes were confirmed again; furthermore, we also got some positional candidate gene with potential function of effecting milk production traits. These novel findings in our research should be valuable for further investigation.     

Effect of Zinc Methionine or Zinc Sulfate Supplementation on Milk Production and Composition of Milk in Lactating Dairy Cows

Eighteen lactating dairy cows were used to compare the effects of organic and inorganic Zn supplements on milk production and chemical composition of milk. Animals received three diets in a randomized block design: basal diet with no supplemental Zn (control, 42 mg Zn/kg), basal diet plus 500 mg Zn/kg of dry matter (DM) as zinc sulfate monohydrate (ZnS) and basal diet plus 500 mg Zn/kg of DM as zinc methionine (ZnM). Results showed that milk and fat-corrected milk yield in dairy cows were not significantly affected by Zn source although a numerical increase was observed. The percentages of protein, lactose, fat, solid nonfat, total solid, and density of milk were not significantly different between treatments. However, dairy cows that received ZnM tended to produce more milk and fat-corrected milk with a lower somatic cell count as compared to controls. The zinc concentration in milk in the ZnM and ZnS groups was higher (P < 0.05) than in milk from the control group, but there were no significant differences between ZnS and ZnM groups.     

绵羊Cytb基因序列多态性及系统进化研究

以8个中国地方绵羊品种和1个外来品种的20个个体为研究对象,通过对Cytb基因的全序列测定,结果表明：绵羊的单倍型多样性为97．1％。所有序列的平均碱基组成为27．1％T,28．5％C,31．4％A及13．0％G,G＋C含量为41．5％,核苷酸多样性为0．602％。在所有序列中共检测到43个变异位点,其中包括40处转换和3处颠换。Fu’S中性检验表明差异不显著（0．10〉P〉0．05）,说明绵羊群体未发生群体扩张事件。NJ、ME及UPGMA聚类结果均表明,我国绵羊可分为3个单倍型组,这提示我国绵羊有3个母系起源。     

水稻无内稃突变体的遗传分析和基因定位

花器官发育异常的突变体是研究植物花发育分子遗传机制的良好实验材料,以水稻无内稃突变体为父本,生47、N625和CDR22为母本配制杂交组合进行性状遗传分析,根据F2代表型及X^2测验结果表明,突变性状是由单隐性基因控制的,选用突变体为父本,生47为母本杂交的F2群体作定位群体,利用SSLP标记的和RFLP标记将与突变性状相关的基因定位在第6染色体短臂上RFLP标记C498和RZ450之间,暂定名为npa-1。为进一步的基因克隆及功能研究奠定了基础。