鸡γ-干扰素基因的克隆及原核表达

参照Digby发表的鸡γ-干扰素的核苷酸序列，设计一对引物，应用RT—PCR技术，从ConA诱导过的鸡脾淋巴细胞中特异性地扩增出大小约为500bp的基因片段。将该扩增基因进行克隆测序，结果表明其序列与Digby报道的CHIFN-γ基因序列的同源性达100％。将该基因插入原核表达载体pGEX-4T-γ中构建成重组表达载体pGEX—CHIFN-γ，并将其导入大肠杆菌BL21中，诱导表达的重组蛋白经SDS—PAGE分析，分子量约为43ku，表明所克隆的CHIFN-γ基因在原核细胞中得到了表达。     

鸡γ-干扰素基因的克隆及原核表达

参照Digby 发表的鸡γ-干扰素的核苷酸序列,设计1对引物,应用反转录聚合酶链式反应(RT-PCR)技术,从Con A诱导过的鸡脾淋巴细胞中特异性的扩增出大小约为 500 bp的基因片段。将该扩增基因进行克隆测序,结果表明其序列与Digby报道的CHIFN-γ基因序列的同源性达100%。将该基因插入原核表达载体pGEX-4T-1中构建成重组表达载体pGEX-CHIFN-γ,并将其导入大肠杆菌BL21中,诱导表达的重组蛋白经 SDS-PAGE 分析分子质量约为 43 ku,表明所克隆的CHIFN-γ 基因在原核细胞中得到表达。     

猪γ干扰素的体外表达及其多克隆抗血清的制备

从健康仔猪前腔静脉无菌采血,分离外周血单个核细胞,提取细胞总RNA,用猪γ干扰素(IFN-γ)基因特异性引物通过RT-PCR扩增猪IFN-γ的全长cDNA序列,将其克隆到pMD18-T载体中,再亚克隆到pUC18和表达载体pET-30a中,经测序发现其序列与GenBank报道的IFN-γ基因序列基本一致.将重组质粒pET-30a-IFN-γ转化大肠杆菌BL21,于37℃经IPTG诱导表达,IFN-γ基因获得表达,表达产物以包涵体形式存在,占菌体总蛋白的39%.经SDS-PAGE及Westernblot分析表明,表达的融合蛋白分子量约为25 ku.将包涵体用8 mol/L脲变性,用ProBondTM Purification Systerm纯化,经透析复性,得到纯化的目的蛋白,含量可达0.3 mg/mL.将复性蛋白免疫新西兰白兔三次,制备了高滴度的猪IFN-γ抗血清.本实验表达和纯化了猪IFN-γ,并制备兔抗猪IFN-γ的抗血清,为下一阶段关于猪γ干扰素重组蛋白其应用奠定了基础.     

鸡γ-干扰素基因的克隆及原核表达

参照Digby发表的鸡γ-干扰素的核苷酸序列，设计一对引物，应用RT-PCR．技术，从ConA诱导过的鸡脾淋巴细胞中特异性地扩增出大小约为500bp的基因片段。将该扩增基因进行克隆测序，结果表明其序列与Digby报道的CHIFN-γ基因序列的同源性达100％。将该基因插入原核表达载体pGEX-4T-1中构建成重组表达载体pGEX-CHIFN-1，并将其导入大肠杆菌BL21中，诱导表达的重组蛋白经SDS-PAGE分析，分子量约为43ku，表明所克隆的CHIFN-γ基因在原核细胞中得到了表达。     

人MxA基因的原核表达及其抗血清的制备

本试验旨在利用大肠杆菌BL21(DE3)表达MxA融合蛋白pET32a(+)-MxA,制备兔抗人MxA抗血清。采用PCR技术获得MxA基因,然后将MxA基因重组到pET32a(+)载体中,筛选阳性克隆,转化大肠杆菌,IPTG诱导表达,用超声波裂解重组菌BL21(DE3)培养物,纯化蛋白质后免疫新西兰兔制备抗血清。SDS-PAGE分析结果显示,pET32a(+)-MxA融合蛋白在大肠杆菌BL21(DE3)菌株中以包涵体形式高效表达;获得的抗血清经间接ELISA法检测效价为1∶6400;Western blotting检测结果显示,抗血清可与真核表达的MxA蛋白进行特异性结合。试验结果表明,在大肠杆菌中成功表达了pET32a(+)-MxA融合蛋白,制备了具有高度特异性的兔抗人MxA抗血清,这样为采用酶标法测定病毒患者全血细胞或由干扰素诱导的细胞产生的MxA蛋白质含量及临床诊断试剂盒的开发和应用打下了基础。     

鸡PPAR-γ基因表达载体构建及抗血清制备

为构建鸡PPAR-γ基因的原核和真核表达载体并制备鸡PPAR-γ的抗血清,根据鸡PPAR-γ基因cDNA序列设计一对引物,采用RT-PCR的方法扩增鸡PPAR-γ基因的cDNA片段并将其分别插入到原核表达载体pGEX-4T-1和真核表达载体pcDNA3中;进而诱导重组原核表达载体pGEX-4T-1/PPAR-γ在大肠杆菌BL21中表达;同时利用重组真核表达载体pcDNA3/PPAR-γ免疫注射小鼠使其产生免疫应答。SDS-PAGE结果显示pGEX-4T-1/PPAR-γ在大肠杆菌BL21中得到了高效的表达。ELISA和Western blot结果表明,pcDNA3/PPAR-γ免疫小鼠产生了效价较高和特异性较强的抗体。本研究所构建的真核表达载体pcDNA3/PPAR-γ为在细胞水平上研究鸡PPAR-γ基因超表达提供了有力的工具;所获得的重组蛋白和抗血清为在蛋白水平上研究鸡PPAR-γ基因的功能奠定了基础。     

大肠杆菌O157:H7候选效应蛋白Z1370的原核表达、纯化及多抗制备

为鉴定肠出血性大肠杆菌O157:H7的效应蛋白,本研究利用生物信息学方法预测了1个新的大肠杆菌O157:H7分泌蛋白Z1370,并以EDL 933菌株为模板,扩增Z1370基因。将该基因克隆至原核表达载体p GEX-6P-2,转化大肠杆菌XL-1 Blue,IPTG诱导目的蛋白表达。利用谷胱甘肽琼脂糖珠和Pre Scission Protease酶纯化目的蛋白。纯化的目的蛋白免疫小鼠制备多抗血清并鉴定多抗血清的免疫反应性和特异性。结果表明,Z1370可能是一个能够分泌至细胞外的效应蛋白。将PCR扩增的Z1370基因连接表达载体并成功在大肠杆菌以可溶形式表达了具有良好天然构象的蛋白,该蛋白在大肠杆菌O157:H7中可以自身催化,并以小于原始相对分子质量的形式存在。将该蛋白纯化后免疫小鼠制备了具有良好免疫反应性和特异性的多抗血清。这为Z1370蛋白的亚细胞定位和功能研究奠定了基础、提供了研究工具。     

山羊IL-2的体外表达及其多克隆抗血清的制备

应用RT-PCR方法从山羊外周血淋巴细胞中克隆了山羊白细胞介素-2(Caprine interleukin-2,CapIL-2)基因并进行测序,将编码山羊IL-2蛋白的基因亚克隆至pET30a( )上,转化大肠杆菌BL21(DE3)并用IPTG于37℃诱导培养。表达融合蛋白通过ProBondTM蛋白纯化试剂盒纯化。纯化产物经3次免疫新西兰白兔,制备出山羊IL-2抗血清。本次试验成功地表达、纯化了山羊IL-2,并制备出兔抗山羊IL-2抗血清,为下一步开展山羊IL-2重组蛋白的应用研究奠定了基础。     

猪源T细胞免疫球蛋白黏蛋白域蛋白-1(TIM-1)多克隆抗体制备与鉴定

为了探究猪源T细胞免疫球蛋白黏蛋白域蛋白-1(sTIM-1)的生物学功能,制备sTIM-1多克隆抗体,通过软件分析sTIM-1蛋白抗原表位及亲水性,并设计引物,以sTIM-1基因为模板扩增sTIM-1黏蛋白功能域编码基因(sTIM-1-M),成功构建了重组表达质粒pET28a-sTIM-1-M,并在大肠杆菌Rosetta 2中诱导表达。以纯化的重组蛋白sTIM-1-M与佐剂混合免疫新西兰大白兔制备多抗血清。SDS-PAGE及Western blot证实了该重组蛋白在大肠杆菌中以可溶性形式表达,分子量约为36 kDa。经Western blot与免疫荧光试验(IFA)验证sTIM-1多抗血清可特异性识别293T细胞表达的sTIM-1。免疫沉淀(IP)结果显示制备的多抗血清可与sTIM-1蛋白互作。以上数据表明本研究制备的sTIM-1多克隆抗体具有良好的反应性和特异性。sTIM-1多克隆抗体的制备为进一步研究sTIM-1参与病毒入侵细胞的机制奠定了基础。     

鸡Mx基因的表达及其抗血清的制备

Mx蛋白已被证明具有抗A型流感病毒、Thogoto病毒和水泡性口膜炎病毒等的生物活性.本研究通过PCR扩增,将Mx基因克隆至pMD18-T载体;经测序验证后将Mx基因克隆到原核表达载体pProExHTa和pcDNA3.1中.以构建的重组质粒pProExHTa-Mx转化大肠杆菌BL21,进行诱导表达,以切胶纯化方式回收了Mx融合蛋白,加佐剂乳化,免疫新西兰白兔制备抗血清;SDS-PAGE和western blot分析表明:Mx基因在大肠杆菌中以融合蛋白形式稳定表达,表达产物的相对分子量约80 ku,与预期值相符;抗血清能与Mx蛋白发生特异性反应.以真核表达重组质粒pcDNA3.1-Mx转染293T细胞,间接免疫荧光试验结果表明:原核表达蛋白免疫动物制备的抗血清与真核表达的Mx蛋白发生良好的免疫反应,表明用原核表达的Mx蛋白具有真核表达Mx蛋白相似的免疫学活性.抗血清的制备为鸡Mx蛋白的功能研究、Mx蛋白在转基因动物机体中表达的检测奠定了基础.     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein     

Evaluation of the Microbiological Status of Milk and Various Structures in Mammary Glands from Naturally Infected Dairy Cows

A knowledge of the microbiological status of milk and of the different structures in the mammary glands has great importance in elucidating the pathogenesis of mammary gland infections. The objective of this study was to evaluate the microbiological status of various structures in the mammary glands from naturally infected dairy cows following slaughter. A total of 94 samples of milk, 184 samples of mammary parenchyma, 168 samples of gland cisterns, and 168 samples of teat cisterns were collected for microbiological examination. Microorganisms were detected in 59.9% of all samples, 67.0% of the milk samples, 70.1% of the mammary parenchymas, 55.9% of the gland cisterns and 48.8% of the teat cistern samples. When all samples were considered, coagulase-negative Staphylococcus were the most prevalent (35.7%) followed by coagulase-positive Staphylococcus (12.2%), Corynebacterium bovis (2.4%), Prototheca sp. (1.9%), and Streptococcus dysgalactiae (1.5%). There was a significantly higher occurrence of microorganisms in the milk and mammary parenchyma compared to the gland cisterns and teat cisterns. This revised version was published online in July 2006 with corrections to the Cover Date.     

Development and survival of free-living stages of gastrointestinal nematodes of sheep and goats on pasture in the Nigerian derived savanna

Four grass plots were sequentially contaminated with goat faeces containing known numbers of unembryonated eggs of predominantly Haemonchus contortus and Trichostrongylus spp. between October 1982 and April 1983. Four other plots were similarly contaminated with sheep faeces between February and May 1987. An additional plot was repeatedly contaminated with sheep faeces from February to April 1987. Populations of free-living stages in faeces and of infective larvae (L₃) in the herbage were subsequently monitored until the end of April and June of 1983 and 1987 respectively. During February and May 1987 two control cultures of sheep faeces were incubated in the laboratory at 25°C–30°C and at a constant temperature of 50°C and the free-living development was also monitored. L₃ developed very readily in the faeces cultured at 25°C–30°C and in those spread on a grass plot in October, at the end of the wet season, but developed less on the plot contaminated in May at the start of the wet season. Worm eggs in faeces deposited on plots during the hot dry season (December to April) or incubated at 50°C died and disintegrated after 24–48 h exposure to the high environmental temperatures. The results indicate that it is unlikely that gastrointestinal nematodes of sheep and goats can develop or survive on open pasture during the dry season in the Nigerian derived savanna zone.