动物转基因的整合、表达及其调控方法

本文综述了转基因在动物体内整合表达机制的研究进展,以及基因构件、调控序列、转基因拷贝数和载体序列等对转基因整合表达的调控,并对转基因技术的现状与前景做了小结和展望。     

舍内喷洒中草药制剂预防断奶仔猪腹泻的试验效果

从改善“外环境”的角度,探讨在舍内喷洒中草药粉剂对早期断奶仔猪腹泻的预防效果。选择64头28日龄断奶的仔猪,随机均分成两组,对照组按常规饲养,试验组在舍内定期喷洒中草药制剂。结果表明,试验组断奶仔猪的腹泻率比对照组降低了4063个百分点;日增重和采食量分别比对照组提高了135%（P＜005）和35%（P＜005）;料肉比较对照组降低了85%（P＜005）。试验表明,在猪舍中定期喷洒中草药制剂能够明显减少早期断奶仔猪的腹泻,提高仔猪的生长性能。     

夏季发酵床猪舍对肥育猪生长性能的影响

解决环保难题是目前养猪业实现可持续发展面临的重大挑战,在此背景下,以号称“零排放”为主要特点的发酵床养猪法,在商业公司和各级地方政府的宣传推动下,呈现出星火燎原之势。     

Early echocardiographic predictors of myxomatous mitral valve disease in dachshunds

Myxomatous mitral valve disease in dogs is heritable, and it is therefore important to detect the early signs of the disease. This study was conducted to assess the predictive value of early echocardiographic and auscultatory signs of mitral valve prolapse, measured in terms of the leaflet thickness, the area of the regurgitant jet, and the intensity of the murmur, on the increases in left ventricular end diastolic diameter (LVEDD) and left atrial diameter (LAD) in a population of 190 clinically healthy dachshunds followed up for three years. The most significant predictor of an increase in LVEDD was the interaction between the index of mitral valve prolapse and the area of the regurgitant jet (P < 0.0001). In dogs with a jet area greater than 50 per cent of the left atrium, the disease progressed more quickly in terms of increases in LVEDD in relation to the severity of the prolapse at the initial examination. In dogs with smaller jets, the initial prolapse index was not significantly associated with increases in LVEDD. The initial index of mitral valve prolapse, the area of the jet and the intensity of the heart murmur were all significant predictors of an increase in LAD.     

A Marek's disease virus vIL-8 deletion mutant has attenuated virulence and confers protection against challenge with a very virulent plus strain

Marek's disease virus (MDV) is an alpha-herpesvirus that causes rapid development of T-cell lymphomas in chickens. MDV-encoded vIL-8 is homologous to the cellular IL-8 gene, and its function in MDV pathogenesis has yet to be determined. Using overlapping cosmid clone-based technology, we have generated an MDV vIL-8 deletion mutant virus, rMd5/delta vIL-8. In vivo experiments with this mutant virus demonstrated that deletion of vIL-8 results in attenuation of the virus and induction of significantly less gross tumor, both in viscera and nerves, when compared to the parental virus. Reintroduction of the vIL-8 gene in the genome of the mutant virus restored the virulence of the virus to the wild-type levels, indicating that vIL-8 plays a role in MDV-induced pathogenesis. In this study, we show that there is a significant difference in the reduction of B cells and activation of T cells in the spleen cells of chickens inoculated with parental rMd5 and vIL-8 deletion mutant virus. These results indicate that vIL-8 is involved in the early phase of pathogenesis, presumably by attracting target cells to the initial site of infection. In addition, protection studies with the vIL-8 mutant virus showed that this mildly virulent virus protects susceptible maternal antibody-positive viruses at a higher level than the commonly used serotype 1 CVI988 vaccine. These results confirm the potential of partially attenuated viruses as vaccines against very virulent plus strains and the usefulness of recombinant DNA technology to generate the next generation of MDV vaccines.