硒对硒蛋白-谷胱甘肽过氧化物酶基因表达及其酶活性的调节

本文根据国内外研究现状详细综述了硒调节细胞型谷胱甘肽过氧化物酶(GPX1)mRNA水平、蛋白水平及酶活3个水平的可能分子机理,初步概述硒对其余GPX基因表达的影响及其作用机制,为深入研究硒调节GPX基因表达的作用机制提供参考。     

咪鲜胺原药中微量2,4,6-三氯苯酚测定方法的研究

建立了高效液相色谱法测定咪鲜胺原药中微量2,4,6-三氯苯酚含量的方法。采用Hypersil BDS C18色谱柱,以甲醇/水(72/28 V/V)为流动相(每500mL流动相中含0.5g四丁基溴化铵),检测波长为296nm,2,4,6-三氯苯酚的质量浓度在0～871.2μg/L范围内线性关系良好,其线性相关系数为0.999 8;加标回收率为99.71%～102.02%,变异系数为1.14%,检出限为0.88μg/L。     

猪轮状病毒Vp4全基因与乳酸菌非抗性表达载体的重组及在大肠杆菌中的表达

以猪A组轮状病毒mRNA为模板，应用优化的反转录聚合酶链式反应（RT—PCR）技术，扩增了2331 bp的Vp4全长基因，通过T-A克隆技术，将PCR产物克隆至克隆载体pGEM-T中，构建质粒pGEM-T-Vp4。以SalⅠ和KpnⅠ双酶切pGEM—T—Vp4．和以胸苷酸合成酶基因（thymidylate synthase，thyA）为选择压力的非抗生素抗性的穿梭表达载体pW425t，并将纯化的Vp4基因亚克隆至表达载体pW425t中，构建出可以在乳酸菌与大肠杆菌之间穿梭表达的原核表达重组质粒pW425t-Vp4。将pW425t-Vp4转化至thyA基因缺陷型的大肠杆菌感受态E．coli X13中，通过生长功能弥补筛选阳性克隆，SDS-PAGE分析，可见约87.67Ku融合蛋白。Western blot分析表明，该蛋白具有与轮状病毒多克隆抗体的反应原性，研究结果为pW425t-Vp4在乳酸菌受体菌株中表达提供科学依据。     

喷施KH_2PO_4对胡萝卜采种的影响

通过叶面喷施磷酸二氢钾(KH2PO4)溶液,对胡萝卜种株生长势、种子产量、质量和种子活力进行了研究。结果表明,种株抽薹后喷施2g·L-1KH2PO4溶液不仅可提高叶片光合速率和蒸腾速率,而且可显著提高种株的茎粗、节长、花盘横径及生物产量,可使种子产量和千粒重显著增加,种子的发芽活力显著提高。     

Characterization of a line of pigs previously selected for increased litter size for RBP4 and follistatin

The objective of this study was to determine if selection response for increased litter size in pigs could be partially attributed to three type 1 marker loci coding for genes known to affect litter size: oestrogen receptor (ESR), retinol‐binding protein 4 (RBP4) and follistatin (FS). In the high litter size line (LS), pigs from the largest litters, based on number of pigs born alive (NBA), were retained to parent the next generation. A randomly selected control line (LC) was maintained. Gilts were reared in litters of 10 pigs or less to minimize maternal effects. Pigs were measured at generations 10–12. Additional traits scored were number of fully formed pigs (NFF) and number of mummified fetuses (MUM). Breeding values for NFF and NBA were greater (p < 0.05) in LS than LC in generations 11 and 12, but no significant line differences were found for MUM. The A allele of the ESR locus was fixed in both lines. After adjustment for effects of genetic drift, frequency of the two alleles segregating for the FS and RBP4 loci did not differ significantly between lines. No significant additive or dominance effects of the FS markers were detected for NFF, NBA and MUM in either LS or LC. Response to selection for increased litter size could not be attributed to effects at the ESR, RBP4 or FS loci.     

Use of β-Glucanases and β-1,4-Xylanases to Supplement Diets Containing Alfalfa and Rye for Laying Hens: Effects on Bird Performance and Egg Quality

It is well established that the use of alfalfa in diets for monogastric animals is limited by its high fiber content. However, alfalfa is a natural source of xanthophylls and gives poultry products a desirably yellow color. In addition, alfalfa saponins may contribute to reduce the levels of cholesterol in the meat and egg yolk. We have investigated the potential utilization of β-glucanases and β-1,4-xylanases for enhancing the nutritive value of alfalfa for laying hens. An experiment was conducted with 864 ISA Brown layer hens from 40 to 52 wk of age and fed on diets containing rye (19.6%) or rye and alfalfa (15.1%). The results suggested that inclusion of alfalfa in the diets reduced body weights and total egg mass (P < 0.01). Dietary supplementation with polysaccharidases was unable to significantly improve the performance of laying hens. However, egg yolks from birds that consumed diets containing alfalfa were more deeply pigmented, presenting an increase in yellowness (b*). In contrast, at the percentage of incorporation tested, inclusion of alfalfa in the diets was unable to lower the levels of cholesterol content in the egg yolk. Taken together the results suggest that exogenous plant cell wall hydrolases are not effective for improving the nutritive value of alfalfa-containing diets for laying hens, although inclusion of small percentages of the dehydrated leguminous meal may directly affect the quality of the generated poultry products.     

利用CAPS标记辅助辣椒PVY抗性基因PVr4转育的研究

利用国外报道的与PVr4基因紧密连锁的CAPS标记,对辣椒抗PVY基因PVr4的转育进行了研究和探讨。采用与报道的相同抗源材料CdM334为回交的供体亲本,与5个自交系77013、75-7-3-1、83077、83078、83-163进行回交,在BC1代进行了分子标记的选择。从5个BC1群体75-7-3-1×(CdM334×75-7-3-1)、77013×(CdM334×77013)、83077×(CdM334×83077)、83078×(CdM334×83078)、83-163×(CdM334×83-163)中,分别检测出含有抗病连锁标记的单株21株、15株、10株、11株、12株。     

鼠防御素cryptdin 4基因在杆状病毒中的表达及活性

以防御素cryptdin4为研究对象，在昆虫一杆状病毒表达系统对cryptdin4基因的成熟肽片段进行表达。通过SDS—PAGE电泳和Western—blot检测，结果发现在相对分子质量8000处出现目的蛋白条带，表明该基因在杆状病毒中获得表达；体外抑菌试验结果显示，目的蛋白具有明显的抗金黄色葡萄球菌、伤寒沙门菌、李斯特菌等指示菌的活性。     

牛TLR4基因的遗传多态性与乳房炎的关联分析

TLR4通过识别病原体而激活免疫细胞，在先天免疫和适应性免疫防御中起着重要作用。以中国荷斯坦奶牛、三河牛和中国西门塔尔牛共397头为研究对象，利用创造酶切位点PCR法扩增243bp的目的片段，通过限制性内切酶HinfⅠ酶切来检测TLR4第3外显子的多态性，结果发现扩增产物的27bp处C到T的突变使得多态位点产生，编码的氨基酸由苏氨酸变为异亮氨酸。A、B2个等位基因在3个群体中均有分布，A等位基因占优势（大于78％），经χ^2适合性检验，三河牛在该位点未达到Hardy-Weinberg平衡状态（P〈0．05）。运用SAS8．2软件采用最小二乘法拟合线性模型，将该基因座不同基因型与奶牛乳房炎进行了关联分析，结果表明：AA基因型为乳房炎抗性基因型（P〈0．05），A等位基因为乳房炎抗性的有利基因。     

鹅黑素皮质素受体-4基因的克隆与序列分析

黑素皮质素受体-4（Melanocortin receptor-4,MC4R）是其黑素皮质素受体MCR（MC1-5R）家族成员之一,属G蛋白偶联受体。它可与瘦蛋白、神经肽、α-黑素细胞刺激素等一起调节动物体重和采食量。参考鸡MC4R基因序列设计引物,克隆并测序了鹅MC4R基因。结果表明,鹅MC4R基因编码区全长996 bp,其核苷酸序列与鸡的同源性为95.3%,与人、牛、猪等哺乳动物同源性在75%-79%;其氨基酸序列与鸡的同源性达到98.5%。构建哺乳类、鸟类和鱼类MC4R基因核苷酸进化树显示,鹅较早地与哺乳类动物分化开来。分析MC4R蛋白的氨基酸残基特性参数表明,MC4R的7次跨膜结构与MC4R的亲水性区域、电荷密度以及氨基酸残基位于表面概率的变化规律相一致。