牛抵抗素基因的克隆及原核表达

从健康新生牛大网膜脂肪组织中提取总RNA,根据已发表的牛Resistin mRNA序列设计、合成引物,通过RT-PCR进行cDNA扩增,获得了343 bp的片段。将该片段克隆于pMD18-T载体后进行序列分析,确认PCR产物为牛Resistin cDNA。从阳性克隆中提取质粒,经BamHⅠ和XhoⅠ双酶切,回收343 bp的目的片段,定向克隆到pGEX-6P-1表达载体中,提取质粒并再次转化到BL21(DE3)中,成功地筛选出阳性克隆。经IPTG诱导阳性菌,通过SDS-PAGE检测出牛的Resistin基因的表达。     

猪繁殖和呼吸综合征病毒分子生物学研究进展

猪繁殖和呼吸综合征病毒（ＰＲＲＳＶ）是引起母猪流产和仔猪呼吸道症状及死亡的一种新的重要病原。该病毒于１９９１年７月首先由荷兰分离获得（当时,称之为Ｌｅｌｙｓｔａｄ病毒,ＬＶ）,接着,德国、美国、比利时、英国、苏格兰、法国、西班牙、日本、韩国及台湾等很...     

新城疫活疫苗对控制鸡大肠杆菌病的效果观察

为了研究鸡新城疫活疫苗紧急免疫控制鸡大肠杆菌病的效果,通过大肠杆菌人工感染30日龄蛋鸡,待出现病症后,紧急免疫新城疫La-sota弱毒苗(Ⅳ系)4羽份.免疫后5～17 d,通过血凝抑制试验测定血清新城疫抗体水平,试验组新城疫抗体水平逐步提高,对照组抗体略有下降,免疫后17 d两组抗体水平差异显著(P＜0.05);对照组...     

不同浓度甘油和pH对DEAE-纤维素柱分离伊氏锥虫效果的影响

在不同ｐＨ条件下以不同浓度甘油破坏鼠红细胞后,用ＤＥＡＥ－５２纤维素柱层析分离纯化伊氏锥虫（Ｔｒｙｐａｎｏｓｏｍａｅｖａｎｓｉ）,结果表明在ｐＨ７．４时,２０％甘油能溶解大约９５％的大、小鼠红细胞;经此处理后,对Ｔ．ｅｖａｎｓｉ的回收率和活力无不良影响,可明显提高其分离纯化效果。作者还观察了渗透压和ｐＨ条件改变对Ｔ．ｅｖａｎｓｉ的影响。     

Bactrian camel (Camelus bactrianus) integrins αvβ3 and αvβ6 as FMDV receptors: Molecular cloning, sequence analysis and comparison with other species

Integrins are heterodimeric adhesion receptors that participate in a variety of cell–cell and cell–extracellular matrix protein interactions. Many integrins recognize RGD sequences displayed on extracellular matrix proteins and the exposed loops of viral capsid proteins. Four members of the αv integrin family of cellular receptors, αvβ3, αvβ6, αvβ1 and αvβ8, have been identified as receptors for foot-and-mouth disease virus (FMDV) in vitro, and integrins are believed to be the receptors used to target epithelial cells in the infected animals. To analyse the roles of the αv integrins from a susceptible species as viral receptors, we have cloned Bactrian camel αv, β3 and β6 integrin cDNAs and compared them to those of other species. The coding sequences for Bactrian camel integrin αv, β3 and β6 were found to be 3165, 2289 and 2367 nucleotides in length, encoding 1054, 762 and 788 amino acids, respectively. The Bactrian camel αv, β3 and β6 subunits share many structural features with homologues of other species, including the ligand binding domain and cysteine-rich region. Phylogenetic trees and similarity analyses showed the close relationships of integrin genes from Bactrian camels, pigs and cattle, which are each susceptible to FMDV infection, that were distinct from the orders Rodentia, Primates, Perissodactyla, Carnivora, Galliformes and Xenopus. We postulate that host tropism of FMDV may in part be related to the divergence in integrin subunits among different species.     

北方寒地引种抗寒苜蓿品种试验

１９９１、１９９２年两年对１０个抗寒苜蓿品种进行了品种比较试验，鉴选出公农一号、草原一号、草原二号、甘农一号、图牧二号６个苜蓿良种。这些品种适应黑龙江垦区的生态条件，抗寒、抗病性强、长势好、产草量高、品质优良，可以在垦区三江平原推广种植。     

复配材料超声处理对化肥控失效果的影响

利用超声波对化肥控失材料(LCM)进行修饰改性,结果表明对硫酸铵的控失效果随处理时间呈现先升高然后降低的规律,峰值出现在5min.本文对其机理进行初步探讨.     

布鲁氏菌病无疫小区建设与成效

近年来,我国将无疫小区管理理念应用到布鲁氏菌病防控,以养殖场生物安全防控作为切入点,整合优化布鲁氏菌病关键技术措施,结合科学有效的监督管理,全面推动布鲁氏菌病防控工作。本文重点从建设主体、生物安全体系、监测要点等方面介绍了布鲁氏菌病无疫小区建设标准,总结了布鲁氏菌病无疫小区建设对于提升完善养殖场生物安全体系,推进养殖企业从传统防控到生物安全管理、风险管理转型升级,促进产业高质量发展等方面的成效,以期对下一步工作推进提供参考。     

Experiment for Condensing Heat Transfer Performance in a New Type of Horizontal Three Dimensional Inner Microfin Tubes

A new type of three dimenstional inner microfin tube is devoloped. Under four different pressures and in the range of condensing mass velocities from 33 to 153 kg/m2 . s,and by the experimental study of the three kinds of tubes with different microfin parameters, the performances of the condensation heat transfer for R11 in the horizontal microfin tubes and obtained. The experiments show that the inner microfin tube is a hopeful and nighty effective condensing heat transfer enhancement tube.