Transformation-mediated serogroup conversion of Dichelobacter nodosus

Dichelobacter nodosus is the essential causative agent of footrot in sheep. The type IV fimbriae of D. nodosus are required for virulence, are highly immunogenic and immunoprotective, and can be divided into 10 major serogroups. Fimbrial variation has been postulated to have arisen because of genetic recombination within the fimbrial gene region perhaps as a means of evading the immune response invoked by infection. To show that antigenic variation in these fimbriae could occur after natural transformation and subsequent homologous recombination, a suicide plasmid containing the fimbrial subunit gene, fimA, of a serogroup G strain was used to convert a serogroup I strain to serogroup G. The resultant mutants were shown by Western blotting and slide agglutination to produce serogroup G fimbriae, but by two independent methods to still have the genotype of the parent type I strain. These data have significant implications for the use of fimbrial vaccines for the control of ovine footrot and suggest that benign strains of D. nodosus could play an important role as a reservoir of alternative fimbrial antigens.     

贵州足球场草坪建植及化管理模型研究

在一定的生境和管理条件下,以修剪高度、修剪次数和施N、P、K量为因素,利用二次正交回归设计,用模糊综合评分法评定草坪质量,最佳3因子水平为:修剪高度5～7.4cm,修剪次数4～6次/月,施N量为2.5～3.7g/(m2·年),施P、K量各为L25～1.85g/(m2·年),建立了草坪质量与养护3因子间的显著相关回归模型.     

Equine perioperative fatalities associated with general anaesthesia at a private practice--a retrospective case series

OBJECTIVE: To determine the fatality rate of horses undergoing general anaesthesia at a private equine referral practice using a limited number of anaesthetic protocols. METHODS: A retrospective analysis of records (n = 17 961) from all horses undergoing general anaesthesia for surgical procedures from 1997 to 2001 at Rood and Riddle Equine Hospital, Lexington, Kentucky, USA. Results were reported as percentage of the population, and as crude mortality rates for each procedure (deaths per 1000). RESULTS: The prevalence of equine fatalities directly related to anaesthesia was 0.12% (n = 21) and this rose to 0.24% (n = 42) with the inclusion of horses killed or dying within 7 days post general anaesthesia. Causes of death directly related to anaesthesia were cardiac arrest (n = 10), fracture in recovery stall (n = 8), neuropathy and myopathy necessitating euthanasia (n = 3). Crude mortality rates per procedure were < or =7 deaths per 1000 cases, except arthrodesis/osteotomy cases were 66.7 deaths per 1000 cases. CONCLUSIONS: The anaesthetic fatality rate at this practice is lower than has been reported previously. CLINICAL RELEVANCE: Familiarity with an anaesthetic protocol in combination with reduced anaesthetic time, emergencies of shorter duration between diagnosis and surgery, and adequate preoperative examination appear to minimize the risks associated with general anaesthesia in horses.     

《木材水运建筑安装工程预算定额》修订和《概、预算编制办法及费用定额》编制

1994年9月～1995年9月,由主编单位四周林业勘察设计研究院承担《木材水运建筑安装工程预算定额》的修订和《木材水运建筑安装工程概、预算编制办法及费用定额》的编制。定额的修定一方面要与相关定额水平协调,同时将工程实体消耗量和施工措施性消耗分开;贯彻政府有关文件精神并反映当前平均先进水平;保留(64)定额的框架只对章,节目和消耗量,基价作调整。 新编《木材水运建筑安装工程概、预算编制办法及费用定额》,以办法与费用定额合一,简化文字实用为原则,项目设置、费用定额符合政府部门最新规定。结合实际控制水平,按工程性质划分为7项生产性主体工程;5项附属性工程;2项非生产性工程和其它工程及费用两大部分。     

中国转基因抗虫棉产业化策略

中国转基因抗虫棉产业化的条件基本成熟，实施转基因抗虫棉产业化应采取创新、合作、务实、高效的策略，实现宽领域、广覆盖。在目标上，强调政策性、社会性、群众性、安全性；在方法上强调市场化、一体化、程序化、法制化；在观念上，强调改变思想、改革投入、改善管理、改进服务；在应用中，巩固传统技术、普及成熟技术、推广辐射技术、试验创新技术；在后续研究时，加强基因库、种质库、数据库和人才库建设。     

The pathogenesis of ovine footrot

Ovine footrot is a contagious and debilitating disease that is of major economic significance to the sheep meat and wool industries. The causative bacterium is the gram negative anaerobe Dichelobacter nodosus. Research that has used a classical molecular genetics approach has led to major advances in our understanding of the role of the key virulence factors of D. nodosus in the disease process. D. nodosus strains produce polar type IV fimbriae and extracellular serine proteases. Mutagenesis of the fimbrial subunit gene fimA and the pilT gene, which is required for fimbrial retraction, and subsequent testing of these mutants in sheep virulence trials has shown that type IV fimbriae-mediated twitching motility is essential for virulence. The extracellular protease genes aprV2, aprV5 and bprV have also been mutated. Analysis of these mutants has shown that ArpV5 is the major extracellular protease and that AprV2 is the thermostable protease that is responsible for the extracellular elastase activity. Structural analysis of AprV2 has revealed that it contains several novel loops, one of which appears to act as an exosite that may modulate substrate accessibility. Finally, virulence experiments in sheep have shown that the AprV2 protease is required for virulence.     

气相色谱-串联质谱法快速检测当归中102种农药残留

建立了当归中102种农药残留的快速检测方法。样品采用优化的QuEChERS前处理方法,利用气相色谱-串联质谱 (GC-MS/MS) 检测,动态多反应监测 (dMRM) 模式,基质匹配外标法定量。结果表明:在样品前处理过程中,经对提取溶剂、提取体系、净化体系的组成和用量进行筛选优化后,样品采用乙腈、1.0 g氯化钠、4.0 g无水硫酸镁、1.0 g柠檬酸钠和0.5 g柠檬酸二钠盐提取,无水硫酸镁800 mg、PSA 150 mg、C₁₈ 150 mg净化,通过基质匹配外标法校正,当归中基质效应对目标化合物的定性、定量影响明显减弱。在0.02~0.64 mg/kg范围内,102种农药的质量浓度与对应的峰面积间呈良好的线性关系,R2均大于0.99,检出限为0.002 5~0.025 mg/kg,定量限为0.005~0.05 mg/kg;在0.04、0.08和0.32 mg/kg 3个添加水平下,102种农药的平均回收率为52 %~128%,RSD为1.0%~10 %。该方法快速简便、耗时短,具有良好的灵敏度、正确度和精密度,为提高当归中农药安全水平,降低健康风险提供了一种快速、高效、可靠的分析手段。     

日粮核苷酸对早期断奶小鼠肝脏基因表达的影响

研究了日粮核苷酸对早期断奶小鼠肝脏基因表达的影响:选取16～17日龄健康BALB/C雄性小鼠60只,分成对照组和实验组,分别饲喂添加0、0.25%核苷酸的无核苷酸基础日粮,在实验的第2、4、10天采用差异显示技术分离小鼠肝脏中差异表达的基因。结果表明:采用6对引物分离到4条差异表达的基因片断。采用差异显示技术初步分离到4个受核苷酸影响差异表达的基因,这些片段需要做进一步的验证。     

Induction of B cell unresponsiveness to noninherited maternal HLA antigens during fetal life

Patients who have received many transfusions become highly sensitized and develop antibodies against almost all HLA alloantigens, so that finding a cross-match negative kidney donor is difficult. A survey of those patients showed that 50 percent did not form antibodies against the noninherited maternal HLA antigens. Apart from the obvious clinical implications, the data indicate that a human equivalent of murine neonatal or actively acquired tolerance has now been identified.