一株无血凝性兔出血症病毒的分离鉴定及其衣壳蛋白VP60基因的克隆和序列分析

从临床病料中分离鉴定出1株无血凝性的致病性兔出血症病毒（RHDV），命名为Yaan-1。HA试验测得该毒株原代及经兔体传3代后的肝毒在25℃、37℃和4℃时均无血凝性；但在琼脂扩散试验和对流免疫电泳中均可见分离株与常规RHDV高免血清形成清晰的沉淀线；电镜观察可见30nm左右的病毒粒子。采用RT-PCR方法将Yaan-1株的衣壳蛋白VP60基因进行了克隆测序，序列分析表明VP60基因序列全长1740bp，编码579个氨基酸，测序结果提交GenBank（注册号为DQ069280），并与世界各国的常规RHDV分离株进行比较，结果表明核苷酸同源性为90．0％～98．0％，氨基酸同源性为94．1％～99．0％，氨基酸变异多发生在衣壳蛋白C、E区；同时对Yaan-1株的分子量、等电点、疏水性、跨膜区等分子结构特征进行了分析。本研究首次报道了无血凝性RHDV中国分离株，丰富了地方毒株资源，为明确我国地方株的分子流行病学，以及对VP60蛋白分子特征研究提供了新材料。     

亚洲璃眼蜱唾液腺一新基因(GP29)的原核表达及产物鉴定

将吸血诱导的亚洲璃眼蜱唾液腺差异表达基因GP29的开放性阅读框插入pGEX-4T-1,转化BL21,表达出一相对质量为53 ku的蛋白,其大小与预计结果一致。蛋白质的肽质量图谱和“1381.7511”肽段序列两方面的结果证明,SDS-PAGE胶板上相对质量为53 ku的蛋白就是由目的基因表达的GST融合蛋白。该蛋白与SwissPROT库中的任何蛋白均有较大差别,可能是一个新功能分子。     

笼养蛋鸭日粮电解质和蛋白质水平对体内酸碱平衡的影响

本试验旨在研究日粮电解质和蛋白质水平对家禽体内酸碱平衡的影响。选取5周龄金定鸭240只,随机分为10个处理,每个处理6个重复,每个重复4只,分别饲喂相同代谢能水平(11.7 MJ/kg),不同粗蛋白质水平(16%或19%)和电解质水平(-50、150、250、350和500 mmol/kg)的10种饲粮。血液生化分析试验结果显示:日粮蛋白质和电解质水平互作对pH、CO2浓度、渗透压、HCO-3浓度的影响极显著(P<0.01),对阴离子间隙的影响不显著(P>0.05)。CP为16%,日粮电解质平衡(dietary electrolyte balance,DEB)为-50 mmol/kg组血液pH显著低于其他各组(P<0.05),其他组间无显著差异。CO2、HCO-3浓度和渗透压各组无显著差异(P>0.05)。日粮蛋白质和电解质水平互作对钠、钾、氯离子和肌酐的浓度有极显著影响(P<0.01),对钙、磷、镁离子、血清尿素氮、葡萄糖、甘油三酯和总胆固醇含量的影响不显著(P>0.05)。代谢试验结果显示:粗蛋白质的利用率各组差异显著(P<0.05),粗蛋白质为16%、DEB为500 mmol/kg组蛋白质利用率最高;粗蛋白质为19%、DEB为250 mmol/kg组最低。钙、磷、钾、铜和锰的利用率粗蛋白质为16%、DEB为500 mmol/kg组最高。两因素方差分析结果表明:蛋白质为19%组粗蛋白质及各种矿物元素的利用率都低于粗蛋白质为16%组。日粮电解质和蛋白质水平对家禽体内酸碱平衡有显著交互作用。     

表达新城疫病毒融合蛋白基因禽痘病毒重组体的构建

通过RT-PCR扩增新城疫病毒F基因,利用禽痘病毒复合启动子、SV40 PolyA终止信号序列构建F基因表达盒。将F基因表达盒与loxp-GFP-loxP序列串联插入禽痘病毒重组臂,构建了禽痘病毒转移质粒载体。在脂质体介导下转染CEF,获得了带有绿色荧光信号的重组病毒rFPVFGFP。通过二次转染,利用Cre-loxP位点特异性重组将重组病毒基因组的GFP自动去除,结果获得了只含新城疫病毒F基因表达盒的重组禽痘病毒rFPVF。试验结果表明,rFPVF复制稳定,表达的F蛋白具有免疫原性,能够刺激鸡只产生抗新城疫病毒的中和抗体。     

牛分支杆菌MPT83基因的表达及重组蛋白的纯化

从牛分支杆菌培养物中抽提总DNA，扩增了MPT83基因，并克隆入pMD-18-T Simple Vector，将测序正确的目的基因插入表达载体pET-32a（＋）中，转化BL21（DE3）宿主菌，IPTG诱导表达，用亲和层析方法对表达蛋白进行了纯化。经测序，构建的克隆质粒pMD-MPT83与Gen-Bank中的序列一致；构建的表达质粒pET-MPT83经PCR和BamHI＋HindⅢ双酶切鉴定构建正确；经SDS-PAGE分析，在约42ku处出现新的蛋白条带，4h后表达量即达到高峰；Westernblotting分析表明，融合蛋白能够被牛分支杆菌阳性血清所识别；纯化的表达蛋白经SDS-PAGE电泳，出现清晰的单一条带。表明MPT83基因原核表达载体构建成功。     

Effects of a high-protein, low-energy diet in finishing lambs: 2. Weight change, organ mass, body composition, carcass traits, fatty acid composition of lean and adipose tissue, and taste panel evaluation

An experiment was conducted to evaluate the effects of a high protein – low energy diet on body composition of feedlot lambs The objective was to assess the capability of such a diet to reduce body fat while preserving lean body mass. Three dietary regimens were compared: a typical feedlot diet (CON), barley straw at libitum (STR), and barley straw supplemented with fish meal (SFM). The latter two diets caused an energy deficit in the experimental animals. Significant treatment effects on mass of metabolic organs, body composition, and carcass data were observed. Conventional analysis of sensory data and fatty acid profiles of adipose and muscle tissue identified few significant dietary effects, yet discriminant analysis clearly separated all treatment groups. It was concluded that protein supplementation of ruminants in the catabolic state does not conserve protein mass. Given the high cost of protein supplementation, the post hoc modification of body composition of feedlot lambs is not a viable option. It is suggested that the production of feedlot lambs with a desirable degree of fatness should employ a feeding strategy dynamically adapted to the changes in protein – energy balance required by the growing ruminant.     

PrP genotype and lamb birth weight in a scrapie-free environment: Is there an association?

The National Scrapie Plan (NSP) for Great Britain includes selective breeding programmes. These aim to reduce the frequencies of the ovine prion protein (PrP) genotypes at high risk of developing clinical disease (principally those containing the VRQ allele) within the national flock, and select for the low-risk ARR-containing genotypes. The aim of this work was to use available data from embryo transfer programmes in guaranteed scrapie-free environments to investigate whether there was a difference in lamb birth weight associated with the lamb's PrP genotype, which might affect survival. The first analysis utilised data from 355 Cheviot lambs born between 2001 and 2004. The analysis was then repeated using a larger data set of 737 Cheviot, Dorset and Suffolk lambs born between 1999 and 2003. The most important determinants of mean lamb birth weight were litter size, sex and recipient ewe breed, plus lamb breed in the three breed analysis. In both analyses the effects of all these variables are consistent and of the same order of magnitude. In the first analysis there was evidence for an apparent increase in mean lamb birth weight for the ARR-containing genotypes of 0.3 kg (95% C.I. 0.1–0.5 kg). Whereas, in the second data set there was evidence for a decrease in mean lamb birth weight for the VRQ-containing genotypes of − 0.6 kg (95% C.I. − 0.8 to − 0.4 kg). This had been masked in the first analysis by the categorisation of these genotypes with the ARQ/ARQ genotype. Within these flocks, in a scrapie-free environment, neither finding provides support for concerns that selection for low risk ARR-containing genotypes would be detrimental to lamb birth weight, which is considered to be the most important determinant of lamb survival. Extension of this work into field flocks, where scrapie-status cannot be easily assured, will require the collection of sufficient data to adjust for known direct effects as well as any additional potential confounding effects.     

亚洲璃眼蜱唾液腺-新基因（GP29）的原核表达及产物鉴定

将吸血诱导的亚洲璃眼蜱唾液腺差异表达基因GP29的开放性阅读框插入pGEX-4T-1，转化BL21，表达出一相对质量为53ku的蛋白，其大小与预计结果一致。蛋白质的肽质量图谱和“1381．7511”肽段序列两方面的结果证明，SDS-PAGE胶板上相对质量为53ku的蛋白就是由目的基因表达的GST融合蛋白。该蛋白与Swiss PROT库中的任何蛋白均有较大差别，可能是一个新功能分子。     

Seasonal changes in digestibility, passage rate and rumen fermentation of alfalfa hay in sika deer (Cervus nippon) under restricted feeding

To investigate seasonal variations in the digestive functions of sika deer, five female sika deer were provided with an amount of alfalfa hay cubes equivalent to voluntary food intake during winter. We measured the rate at which the food passed through the digestive tract, digestibility and rumen fermentation during the summer (August), autumn (November), winter (February) and spring (May). Total mean retention time in the digestive tract during summer and autumn was numerically longer than that in winter and spring, but the difference did not reach significance. Organic matter and fiber were less digestible in summer and autumn than in winter and spring (P < 0.05), whereas the digestibility of the dry matter tended to vary with the seasons (P < 0.1). Ruminal pH values seasonally changed (P < 0.01), and were the lowest in autumn. The concentration of ruminal ammonia‐nitrogen differed significantly among the seasons (P < 0.05), increasing in winter and decreasing during spring and summer. The numbers of protozoa changed significantly among the seasons (P < 0.05), being higher in autumn than in winter and spring, and intermediate in summer. The concentration of total volatile fatty acids was not seasonally affected, but the molar percentages of propionic acid and butyric acid significantly changed according to season (P < 0.05 and P < 0.01, respectively), and the ratio of acetic to propionic acid tended to change with the seasons (P < 0.1). The results of this study suggested that the digestive functions in sika deer, fed a commercial diet at a restricted level, differed notably among the seasons and these variations might partially be due to environmental effects.