Successful suppression of endogenous α-1,3-galactosyltransferase expression by RNA interference in pig embryos generated in vitro

RNA interference (RNAi) technology using small interfering RNAs (siRNA) has been widely used as a powerful tool to knock down gene expression in various organisms. In pig preimplantation embryos, no attempt to suppress the target gene expression with such technology has been made. The purpose of this study is to demonstrate that the RNAi technology is useful for suppression of endogenous target gene expression at an early stage of development in pigs. Alpha-1,3-Galactosyltransferase (α-GalT) is an enzyme that creates the Galα1-3Gal (α-Gal) epitope on the cell surface in some mammalian species, and removal of the epitope is considered to be a prerequisite for pig-to-human xenotransplantation. We decided to suppress the endogenous α-GalT mRNA expression in pig early embryos, since reduction of α-GalT synthesis is easily monitored by cytochemical staining with Bandeiraea simplicifolia isolectin-B(4), a lectin that specifically binds to the α-Gal epitope, and by RT-PCR analysis. Cytoplasmic microinjection of double-stranded RNA and pronuclear injection of an siRNA expression vector into the embryos generated in vitro resulted in a significant reduction in expression of the α-GalT gene and α-Gal epitope in blastocysts, at which stage the α-Gal epitope is abundantly expressed. Somatic cell nuclear transfer of embryonic fibroblasts stably transfected with an siRNA expression vector also led to a significant reduction in the level of α-GalT mRNA synthesis together with decreased amounts of the α-Gal epitope at the blastocyst stage. These results indicate that the RNAi technology is useful for efficient suppression of a target gene expression during embryogenesis in pigs and suggest the possibility of production of siRNA-expressing pigs for use in xenotransplantation.     

制约内蒙古额尔古纳市奶业发展的因素及应对措施

奶业是内蒙古额尔古纳市的支柱产业,加快奶业的发展是该市现阶段农牧业经济发展的一项重要任务。奶业发展步伐的加快,对于带动农业和农村经济结构战略性调整,发展二三产业、增加农民收入、促进经济发展以及提高人民的健康水平具有重要的现实意义。分析了制约额尔古纳市奶业发展的因素,指出应通过强化技术支撑体系建设、改良奶牛品种、加强从业人员培训、加强奶牛生产社会化服务体系建设等措施来解决存在的问题,以进一步发展额尔古纳市奶业。     

影响马精液冷冻保存效率的因素分析

马精液冷冻保存技术对提高马的繁殖效率有重要意义,多种因素会对冷冻保存精液的精子造成损害。本文综述了精清、抗冻剂、微生物、过氧化作用、渗透压、冷冻和解冻等影响马精子冷冻保存的因素,旨在为提高马精液冷冻保存技术的效率、促进我国马产业更快发展提供理论依据。     

Changes in endotracheal tube intracuff pressure and air leak pressure over time in anesthetized Beagle dogs

Objective

To evaluate endotracheal tube intracuff pressure (P_cuff) changes over time and the effect of these changes on air leak pressure (P_leak).

太子参茎叶对断乳仔猪抗氧化和抗应激能力的影响

试验旨在研究太子参茎叶对断乳仔猪抗氧化和抗应激能力的影响。将60头杜-长-大断乳仔猪,随机分为4组,每组3个重复,每个重复5头。空白对照组饲喂基础日粮,试验组分别在基础日粮中添加0.5%、1%和1.5%的太子参茎叶粉,分别于50日龄和70日龄采血,检测血清抗氧化和抗应激指标。结果显示,太子参茎叶添加组试验猪与空白对照组相比,血清中MDA含量显著降低,GSH-Px和SOD活性显著升高,T3、T4和皮质醇含量显著升高。结果表明,太子参茎叶能够显著提高断乳仔猪抗氧化和抗应激能力。     

夏冬季蛋鸡放养的管理措施

本文分析了夏冬季对放养蛋鸡会产生的诸多不利影响,并提出在实际生产中应从营养饲喂、环境条件控制、疾病防控等方面采取针对性地管理措施,以保证蛋鸡放养全年的连续性生产与养殖效益的提高。     

12种中药的体外抑菌试验

研究不同中药对标准菌及临床分离菌的抗菌活性,为中药应用于临床,以及消除细菌耐药性的研究提供基础。采用管碟法,进行了12味中药对3种标准菌及30株临床分离菌的抑菌作用观察。结果显示,12味中药中的8味对金黄色葡萄球菌、大肠埃希菌、沙门菌具有不同程度的抑制作用,其中乌梅、五倍子和黄连抑菌活性最强,木耳、穿心莲、白头翁、苦参无抑菌作用。     

利用间接荧光抗体技术对微小隐孢子虫Cp16蛋白进行抗原定位

Cp16基因是从核糖体展示文库中筛选的微小隐孢子黏附相关基因,为了确定Cp16蛋白是否是微小隐孢子虫卵囊或子孢子表面抗原,构建了Pet-28 a-Cp16原核表达载体,将其转化至BL21大肠杆菌中进行诱导表达,经纯化获得重组蛋白Cp16。将纯化的重组蛋白免疫BAILB/c小鼠,ELISA方法测定IgG抗体滴度。利用间接荧光抗体技术进行抗原定位的初步研究。结果表明:隐孢子虫卵囊表面及子孢子表面富含Cp16蛋白。