HSN1亚型禽流感病毒NA基因在重组禽痘病毒中的表达及其产物的免疫原性

将禽流感病毒A／Goose／Guangdong／1／96（H5N1）株的NA基因及LacZ报告基因克隆到禽痘病毒载体pSY681中，构建重组转移载体pSY（NA＋LacZ），将其转染鸡胚成纤维细胞，经蓝白斑筛选，纯化表达NA基因的重组禽痘病毒rFPV-NA，用其免疫SPF鸡，检测该重组禽痘病毒的免疫原性。结果显示，该重组禽痘病毒能够在体外培养细胞内表达具有生物学活性的NA蛋白，表达产物的分子质量约为55ku；用该重组禽痘病毒免疫SPF鸡后，能够使免疫鸡获得对H5N1和H7N1两种亚型HPAIV攻击的部分保护。表明，重组禽痘病毒rFPV—NA具有良好的免疫原性。     

本地毛形线虫HSP70基因的克隆与序列分析

根据GenBank中已发表的布氏旋毛虫HSP70基因序列设计了1对引物，用Trizol法从本地毛形线虫肌幼虫虫体中提取总RNA，用RT-PCR方法扩增了HSP70基因，将目的基因克隆至pMD18-T载体，转化大肠杆菌DH5α。重组质粒用PCR、限制性内切酶BarnHⅠ和HindⅢ进行单、双酶切鉴定。测序结果表明，成功克隆了本地毛形线虫HSP70基因。序列分析表明，HSP70基因比较保守，不同物种之间氨基酸的同源性在40％～80％。与布氏旋毛虫HSP70序列相比，CDS区多出9个碱基，但核苷酸序列和氨基酸同源性分别为98%和94％，存在1个糖基化位点和1个潜在的信号肽位点。     

影响猪采食量的因素

随着猪生产性能的提高，猪的采食量成为限制生产性能的主要因素之一，猪的采食量直接影响遗传潜力的发挥和生产效益，因此，受到养猪者和研究人员的重视。影响猪采食量的因素很多，包括环境、饲料、健康、遗传特性等，从生理上讲，它主要由下丘脑的摄食中枢和饱中枢控制，下丘脑通过各种调节因子对食欲进行着精细的调节，而且这些调控因子之间存在着交互作用。作者主要对猪群采食量调节机制、影响猪采食量的因素及调控猪采食量的基因研究进展做一综述。     

环境因素影响肉鸡生长的研究进展

就环境因素中温度、湿度、有害气体、光照和饲养密度对肉鸡生产性能的不利影响进行综述,并从内分泌、细胞体液反应、免疫、组织器官和营养代谢角度阐明不利因素影响肉鸡生产效果的机理。     

Expression of vascular endothelial growth factor in canine oral malignant melanoma

Serum, plasma and tissue expression of vascular endothelial growth factor (VEGF) was measured in 20 dogs previously diagnosed histologically with oral melanoma. The concentrations of VEGF in serum and plasma were significantly higher in dogs with melanoma than in a control population (P ≤ 0.002). Concentrations of VEGF in the serum and plasma of dogs with melanoma were highly correlated (r = 0.867). Ninety‐five per cent of melanoma tissues expressed VEGF. Two staining patterns were detected: diffuse and granular cytoplasmic staining. High blood concentrations of VEGF were correlated to a shorter survival time in dogs receiving definitive therapy (P = 0.002). Survival times were significantly longer in dogs receiving definitive therapy versus palliative therapy (median 496 versus 97 days, P = 0.007). Blood concentrations of VEGF were associated with stage (P < 0.05). Dogs with oral melanoma have increased serum, plasma and tissue concentrations of VEGF. Increased expression of VEGF may be a reasonable target for future therapy of canine oral melanoma.     

Application of time-resolved fluorometry to immunoassays for bovine reproductive hormones

The principle of time‐resolved fluorometry with lanthanide chelates was established in the 1980s, but in the field of animal sciences it has not been widely applied to immunoassays. However, immunoassays that utilize time‐resolved fluorometry are possible alternatives to radioimmunoassays, since they can attain high sensitivity without safety risks. In this short review, we introduce the development of time‐resolved immunoassays for inhibin A, inhibin B and follicle‐stimulating hormone (FSH), and describe their application to the investigation of FSH regulation in male and female cattle. The results obtained using these newly developed immunoassays indicate that inhibin A acts as a feedback regulator for FSH secretion in female cattle, whereas inhibin A, and probably inhibin B, do so in male cattle.     

Validation and application of real-time polymerase chain reaction assays for representative rumen bacteria

Real‐time polymerase chain reaction (PCR) assays for 11 representative rumen bacterial species were validated. The sensitivity was tested by using the serially diluted target 16S rDNA from respective bacterial species. The recovery of the target DNA and the assay reproducibility were determined using DNA from rumen fluid spiked with different quantities of the target. Minimum detection levels for the target were 10–100 copies in pure culture. The recovery of the added target ranged from 82.4 to 116.6%. The intra‐ and inter‐assay variations of each assay were <9.4 and <12.6%, respectively. Therefore, the real‐time PCR assays evaluated in the present study are considered to be sufficiently reliable for monitoring all 11 bacterial species in the rumen. The assays were then applied to the monitoring of the bacterial species attached to ruminally incubated rice straw. Among the monitored fibrolytic species, Fibrobacter succinogenes was found to be the most dominant, accounting for 2.61% of total bacteria after 24 h incubation. Selenomonas ruminantium and Streptococcus bovis, non‐fibrolytics, were detected on the rice straw at 8.96% and 1.16% of total bacteria, respectively. Such high levels of non‐fibrolytics on the plant fiber suggest a synergistic relationship between fibrolytics and non‐fibrolytics.     

Effect of polymorphisms linked to LEP gene on its expression on adipose tissues in beef cattle

In cattle, genetic markers at the leptin (LEP) gene and at those linked to the gene have been described as affecting calving interval (markers LEPSau3AI and IDVGA51), or daily weight gain (BMS1074 and BM1500). This work investigated the effect of these alleles on LEP mRNA levels in cattle subcutaneous and omental adipose tissues. A sample of 137 females of a Brangus‐Ibage beef cattle herd was analysed to evaluate the distribution of the polymorphisms; then, animals having at least one of the IDVGA51*181 (allele 181 at marker IDVGA51; six animals), LEPSau3AI*2 (four), BMS1074*151 (13), BM1500*135 (six) alleles and a control group composed of animals without any of these alleles (four animals) were submitted to surgery to obtain omental and subcutaneous adipose tissues. Leptin mRNA expression was quantified by TaqMan RT‐PCR, using 18S rRNA as internal control and adjusted for the effect of body condition score, through regression analysis. Omental fat had LEP gene expression 33% lower than the subcutaneous tissue. Carriers of IDVGA*181 and BMS1074*151 showed subcutaneous fat leptin mRNA levels higher than the controls. Leptin controls feed intake and coordinates reproduction; therefore, animals with higher LEP gene expression will probably have lower daily weight gain than others with similar forage offer and nutritional condition and probably will also have longer calving interval.     

H5N1亚型禽流感病毒神经氨酸酶基因的表达及纯化

用RT-PCR方法从H5N1亚型禽流感病毒（AIV）A／Duck／Zhejiang／12／00中获得NA基因，将目的基因定向克隆到原核表达载体pET-32a中，将序列测定和双酶切验证准确的阳性重组质粒转化大肠杆菌BL21，用IPTG诱导，经SDS-PAGE和Western-blot分析，结果显示，重组蛋白得到了可溶性表达，表达的蛋白质分子质量为33ku；该蛋白可以与禽流感H5N1亚型阳性血清反应，具有良好的免疫原性；ELISA检测结果表明，用此纯化蛋白作为包被抗原检测H5N1亚型AIV神经氨酸酶抗体具有良好的灵敏性。     

低聚木糖和酸化剂对断奶仔猪生产性能的影响

本试验研究了低聚木糖及其与酸化剂合用对断奶仔猪生产性能的影响。选择72头35±1日龄、平均断奶体重(10.33±0.34)kg的健康三元(杜×长×大)杂交仔猪,按体重和性别分成4个处理组,每处理组3个重复。第1组为对照组,饲喂玉米-豆粕型基础日粮;第2组为低聚木糖(200mg/kg)组;第3组为酸化剂(8g/kg)组;第4组为合用组,添加低聚木糖(200mg/kg)和酸化剂(8g/kg)。研究结果表明,各试验组日增重、料重比得到显著改善(P<0.05),腹泻率显著下降(P<0.01)。