西门塔尔牛改良宕昌本地黄牛F1的生长发育性能测定

试验测定了西门塔尔牛与宕昌县本地黄牛杂交改良的效果。结果表明,在当地饲养管理条件下,0～12月龄西本F_1的生长发育性能比本地黄牛得到较大提高,显著促进了当地肉牛产业的发展。     

基于 Photoshop 实现的古代壁画虚拟复原研究

通过对古代壁画颜料特性与褪色变色情况的调查,提出基于Photoshop实现的古代壁画虚拟修复方法,重点讨论褪色变色区域和残缺区域修复与补绘的具体实施方案,最后通过调整色彩中的HSV值还原古老壁画的本来面貌.     

杂交玉米制种花期不遇原因及解决方法

在玉米杂交制种过程中，因父母本花期不遇造成产量下降的现象时有发生。要想夺取高产，成功制种，就有必要了解影响花期不遇的原因及调节措施。     

试论量、本、利分析法在农业科研经济管理中的应用

试论量、本、利分析法在农业科研经济管理中的应用中国农业科学院甜菜研究所韩卫平在市场经济条件下，科研单位必须树立经营观念，加大经济管理的力度，提高经营管理的层次和水平，以改善内部经营管理机制，适应不断发展变化的外部环境，推进科研事业发展。这就要求我们必...     

浅谈彝区黄牛改良现状及技术关键

<正>畜禽良种体系是现代畜牧业的基础保障,建设新型的良种繁育体系,科学高效地选育和推广适应生产条件和市场需求且生产性能高的优良畜禽品种,是实现畜牧业"优质、高产、高效、安全、生态"发展目标的关键。随着经     

浅析干茧茧层率与缫折的关系

在解舒率相对稳定的情况下,干茧茧层率如果出现变化,干茧出丝量也会随之变化.这种变化与缫折的关系如何?近年来,我们就这个问题作了系统的资料搜集、分析、研究,并与生产实绩对照.找出了干茧茧层率与缫折的关系.     

猪人工授精成功的标准和提高措施

1成功的标准 判断猪人工授精是否成功一般以本交作为参照,实践中通常标准如下。     

高校思想道德修养教学要注重以学生为本

高校"思想道德修养"课在教学过程中只有注重以学生为本,充分发挥学生的主体意识、参与意识;及时把握学生的思想动态;关注学生面临的现实问题;注重现代教育技术在思想道德修养课教学中的应用,才能切实提高思想政治教育的针对性、实效性和吸引力、感染力,培养德智体美全面发展的社会主义合格建设者和可靠接班人。     

Investigation of Genetic Variation of B-G Gene with PCR-SSCP and RFLP in Chinese Indigenous Chickens

To reveal genetic variation of MHC B-G gene at Chinese native chickens, two PCR primer pairs were designed to hybridize specifically with conserved sequences surrounding hypervariable regions within the B-G gene and used to amplify two DNA fragments in ten Chinese indigenous chicken breeds and one introduced breed. The fragments were cloned and sequenced to assure that the expected sequences of chicken B-G gene were isolated. Of which the 189 bp fragment encompassing the most variable region within exon 2 of B-G gene was employed for PCR-SSCP assay, this method provided evidence for the presence of at least 56 B-G genotypes in the Chinese chickens sampled. It revealed a high degree of diversity in B-G genes of Chinese local breeds; particularly, high variation of B-G gene was confirmed with the presence of 48 B-G genotypes within Tibetan chicken population. Not only can the B-G genotypes be used to preliminarily screen new B-G alleles, but also they would be utilized to investigate MHC haplotypes and matched unrelated donors for bone marrow transplantation in immune researches. Another fragment of 401 bp size spanning over partial intron 1 and exon 2 of B-G gene was employed for PCR-RFLP analysis with two restriction enzymes of Msp Ⅰ and Tas Ⅰ in the breeds sampled. In this part of the gene, three novel SNPs were detected at the two restriction sites. It was more generally found the transition of two nucleotides of A294G and T295C occurred at Tas Ⅰ restriction site, and consequently led to a non-synonymous substitution of asparagine into serine at position 54 within the deduced amino acid sequence of immunoglobulin variable-region-like domain encoded by the exon 2 of B-G gene. It was observed at rare frequency that an alone mutation of A294G occurring at the site, which also caused the substitution of amino acid, asparagine 54-to-serine;and we haven't found only single mutation occurred at position 295 of the restriction site. At the Msp Ⅰ site, the transversion of G318C led to a non-synonymous substitution, glutamine 62-to-histidine. The variations at expression level caused by the genetic variability of B-G gene may bring about the changes in immune specificity of B-G antigen finally. Furthermore, two alleles, A and B, were identified at Msp Ⅰ and Tas Ⅰ loci of B-G gene, respectively. The allele frequencies were estimated, which gave a nonsymmetrical distribution either in the eight Chinese local breeds or in the introduced breed. By comparison, allele A at Msp Ⅰ locus was tended to be dominative, while, the allele B at Tas Ⅰlocus was tended to be prevalent in the breeds analyzed. It is concluded that the genetic variability of B-G gene revealed by the PCR-SSCP and RFLP assays in Chinese native chickens provide molecular data for further investigating the varied immune functions of B-G antigen; and the PCR-RFLPs at Msp Ⅰ and Tas Ⅰ loci of B-G gene might be used as genetic markers in selecting for the traits of disease resistance in chicken breeding.     

提高黄牛冻精配种受胎率的主要技术措施

牛属大型哺乳动物,其繁殖具有怀孕期长,单胎产犊等特点。因此,要在较短时期内迅速扩大群体数量则很难实现。目前,在尚没有缩短母牛怀孕期的情况下,提高母牛受胎率,降低空怀率和采取人工授精是扩大牛群数量,降低养牛成本的重要措施。冷冻精液人工授精技术是家畜繁殖的一项先进技术,它既能提高受胎率,又能节省饲养种公牛的费用,克服公母牛因体格大小而带来的自然交配困难,预防本交而感染疾病,避免本交带来的过度近交而使后代生产性能下降,较快地繁殖优良后代并进入商品化生产,提高养牛经济效益。冻精配种虽然技术已非常成熟,但具体应用仍存在…