Pyruvate kinase is necessary for Brucella abortus full virulence in BALB/c mouse

Brucellosis, caused by a facultative intracellular pathogen Brucella, is one of the most prevalent zoonosis worldwide. Host infection relies on several uncanonical virulence factors. A recent research hotpot is the links between carbon metabolism and bacterial virulence. In this study, we found that a carbon metabolism-related pyruvate kinase (Pyk) encoded by pyk gene (locus tag BAB_RS24320) was associated with Brucella virulence. Determination of bacterial growth curves and resistance to environmental stress factors showed that Pyk plays an important role in B. abortus growth, especially under the conditions of nutrition deprivation, and resistance to oxidative stress. Additionally, cell infection assay showed that Pyk is necessary for B. abortus survival and evading fusion with lysosomes within RAW264.7 cells. Moreover, animal experiments exhibited that the Pyk deletion significantly reduced B. abortus virulence in a mouse infection model. Our results elucidated the role of the Pyk in B. abortus virulence and provided information for further investigation of Brucella virulence associated carbon metabolism.     

Tolerance of benzalkonium chloride, formalin, malachite green, and potassium permanganate in goldfish and zebrafish

OBJECTIVE: To determine tolerance of goldfish and zebrafish to benzalkonium chloride, formalin, malachite green, and potassium permanganate. DESIGN: Tolerance study. ANIMALS: Adult goldfish (Carassius auratus) and zebrafish (Danio rerio). PROCEDURES: Groups of fish (n = 10/group) were exposed to each disinfectant at the therapeutic dosage; at 0.25, 0.5, 3, and 5 times the concentration used for the therapeutic dosage; and at the concentration used for the therapeutic dosage but for 3 or 5 times the recommended exposure time. RESULTS: In both species, exposure to malachite green at the therapeutic dosage resulted in toxic effects, including death. Exposure to formalin at the therapeutic dosage resulted in toxic effects in goldfish, but not zebrafish, and exposure to potassium permanganate resulted in toxic effects in zebrafish, but not goldfish. On the basis of the ratio of therapeutic dosage to median lethal dosage, in goldfish, formalin was more toxic than benzalkonium chloride, which was more toxic than malachite green, which was more toxic than potassium permanganate. In zebrafish, potassium permanganate was more toxic than formalin and benzalkonium chloride, which were approximately equally toxic and more toxic than malachite green. Extending treatment time increased the toxicity of potassium permanganate in zebrafish and the toxicity of formalin and malachite green in goldfish, but did not alter the toxicity of the other disinfectants. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that there was no consistency between zebrafish and goldfish in their tolerance to disinfectants, and that therapeutic dosages reported in the literature for these disinfectants were not always safe.     

Clinical, humoral and IFNgamma responses of cattle to infection with Mycoplasma mycoides var. mycoides small colony and attempts to condition the pathogenesis of the infection

Contagious bovine pleuropneumonia (CBPP), caused by Mycoplasma mycoides var. mycoides small colony (MmmSC), is one of the most important diseases of cattle in Africa. The role of innate or acquired cell mediated and humoral immunity in conferring protection against MmmSC infection has not yet been elucidated. On the other hand, the pathological lesions caused by the aetiological agent have been considered indicative of an immunopathological process. In this study ten na?ve cattle were exposed to in-contact infection with animals infected by intubation with a strain of MmmSC. Clinical signs, antibody response, IFNgamma release and pathological changes at necropsy were analysed and compared with the events following in-contact infection of an equal number of animals kept under daily treatment with cyclosporine for the entire observation period of 84 days. Cyclosporine is a suppressor of the immune response related to the T-cell system. Under the conditions of the experiment, cyclosporine appeared to condition the pathogenesis of CBPP by delaying the events that follow infection, bringing further support to the possibility that the immune response may have an impact on the disease outcome.     

玉米黄花叶病毒运动蛋白的原核表达纯化与抗血清制备

为实现对玉米黄花叶病毒（maize yellow mosaic virus,MaYMV）的血清学检测,丰富该病毒的检测方法,将编码MaYMV运动蛋白（movement protein,MP）的基因连接到原核表达载体pDBHis-MBP上,将构建成功的原核表达质粒转化到大肠杆菌Escherichia coli中诱导表达融合蛋白,将纯化后的融合蛋白对新西兰大白兔Oryctolagus cuniculus进行免疫并制备MaYMV MP多克隆抗血清,并采用Western blot对抗血清的效价、灵敏度和特异性进行检测。结果显示,利用成功构建的原核表达载体经诱导表达获得分子量大小约为62 kD的融合蛋白,纯化后对新西兰大白兔进行免疫获得MaYMV MP抗血清,该抗血清的效价为1∶128 000,灵敏度为1∶32,且该抗血清能够特异性地检测到本氏烟Nicotiana benthamiana中瞬时表达的MaYMV MP,而不与马铃薯卷叶病毒属Polerovirus及黄症病毒属Luteovirus的其他病毒发生血清学交叉反应,证明该抗血清具有良好的特异性。表明本研究制备的MaYMV MP抗血清能特异性...     

苏氨酸和异亮氨酸对皖西白鹅屠宰性能、器官指数及肠道形态结构、消化酶活性、抗氧化和免疫指标的影响

本试验旨在研究苏氨酸和异亮氨酸对皖西白鹅屠宰性能、器官指数及肠道形态结构、消化酶活性、抗氧化和免疫指标的影响。选取30日龄体重相近的皖西白鹅180只,随机分为3组,每组3个重复,每个重复20只。对照组饲喂基础饲粮,苏氨酸组在基础饲粮中添加2.0 g/kg的L-苏氨酸,异亮氨酸组在基础饲粮中添加2.5 g/kg的L-异亮氨酸。试验期60 d。结果表明：1）各组之间90日龄屠宰性能和器官指数无显著差异（P>0.05）。2）异亮氨酸组60日龄十二指肠和空肠绒毛高度、隐窝深度显著或极显著高于对照组（P<0.05或P<0.01）,苏氨酸组60日龄十二指肠、空肠和回肠隐窝深度及90日龄十二指肠和回肠绒毛高度显著或极显著高于对照组（P<0.05或P<0.01）。3）苏氨酸组和异亮氨酸组60、90日龄十二指肠胰蛋白酶活性极显著高于对照组（P<0.01）,苏氨酸组60、90日龄十二指肠麦芽糖酶活性及90日龄空肠淀粉酶、乳糖酶活性显著或极显著高于对照组（P<0.05或P<0.01）。4）异亮氨酸组60日龄空肠总抗氧化能力显著高于对照组和苏氨酸组（P<0...     

pBI121载体酶切位点添加及拟南芥Na+/H+逆向转运蛋白基因表达载体的构建

对pBI121载体GUS基因后的终止子序列（Sac Ⅰ-EcoR Ⅰ）通过PCR扩增法进行了酶切位点的添加，即在SacⅠ后添加了XhoⅠ、在EcoRⅠ前添加了KpnⅠ。序列分析发现，两个酶切位点的添加是成功的，但扩增的终止子序列与原序列的同源性间有差异，即有4个碱基发生了变异，特别是第17个碱基位点出现了缺失。利用绿色荧光蛋白（GFP）对添加酶切位点载体进行了终止子活性的检测，结果发现，它与携带GFP的pBI121载体一样，GFP基因能正常表达，说明pBI121载体终止子序列酶切位点的添加是成功的。利用改造后的载体（pBI121-GZ）构建了CaMV35S启动子驱动AtNHX1基因的植物表达载体。     

几种外源激素对韭葱种子发芽的影响

本试验以韭葱为材料,用几种不同浓度的外源激素:吲哚乙酸(IAA)、萘乙酸(NAA)和赤霉素(GA3)处理,结果表明,除100 mg/L的NAA外,各种处理对韭葱种子的发芽势和发芽率都有一定程度的提高,其中以50 mg/L的GA3处理效果最佳.     

农杆菌介导的马铃薯茎段遗传转化体系优化研究

以甘肃主栽品种的茎段为外植体,研究了不同转化条件(菌液浓度、感染时间、预培养及共培养时间)对转化效率的影响,以及选择压和培养基对抗性出芽的影响,初步建立了马铃薯品种“陇薯3号”和“台湾红皮”的遗传转化体系并获得了转化植株。卡那霉素生根筛选和PCR鉴定结果表明,再生的转化植株假阳性率比较高,要获得预期的转基因植株群体需加大遗传转化工作中转基因植株的数量。