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31.
Stillborn and mummified swine fetuses from swine farms experiencing reproductive problems were investigated for evidence of infection with encephalomyocarditis (EMC) virus by fetal serology, virus isolation, and histopathologic examination. Fetal sera or thoracic fluids of 478 abnormal fetuses collected during January through December 1987 were tested for the presence of antibody specific to EMC virus. Of 478 samples tested, 175 (36.6%) had EMC virus serum neutralizing antibody titers of 1:64 or greater. The samples positive for EMC virus antibody were obtained from 38 swine farms located in 9 states in the United States. In addition to serologic observations, tissue samples of some abnormal fetuses were examined for the presence of virus and histopathologic lesions. The EMC virus was isolated in 1 case from the fetuses of an aborted litter. The isolate was serologically identical to a reference EMC virus. Nonsuppurative encephalitis and myocarditis were observed in the fetal samples collected from 2 different herds. Thoracic fluid of 1 stillborn pig with lesions was positive for EMC virus antibody at a titer of 1:512. We suggest that a widespread reproductive problem recently experienced in several major swine-producing areas of the United States may have been caused by EMC virus infection.  相似文献   
32.
黑蚱蝉的鸣声和其发音器,具有基本的构造和特性,即种性.但也有一定的地理差异,鸣声有单音色,复合声,主峰频率高低等变化,这和形态的大小,发音器及其辅助发音器的变化相一致.黑蚱蝉的召唤声和求偶声是鸣声分类较理想的类型,而群鸣声不能用于种下分类.  相似文献   
33.
Antagonism of medetomidine sedation by atipamezole in pigs.   总被引:1,自引:0,他引:1  
The efficacy of atipamezole as a medetomidine antagonist was evaluated in pigs. The atipamezole doses (intramuscularly) were 80, 160, 320 and 480 micrograms/kg of body weight, which were one, two, four and six times higher than the preceding medetomidine dose (80 micrograms/kg, intramuscularly). Atipamezole effectively reversed medetomidine-induced sedation, and the optimal action was seen at doses of 160 and 320 micrograms/kg. Recovery from sedation was quick and smooth, and adverse effects such as hyperactivity or tachycardia were minimal with either dose.  相似文献   
34.
我省土地荒漠化和沙化监测主要包括3个荒漠化监测站和5个沙化监测站,布设监测样地28个。确定了采集监测区域内气象、土壤、水文、生物等方面的信息和方法。  相似文献   
35.
乳酸菌与中药合生元对肉鸡生长性能及饲料利用率的影响   总被引:3,自引:0,他引:3  
本试验分别向肉仔鸡日粮中添加等量的抗生素和乳酸菌与中药合生元制剂,通过测定肉仔鸡的各项生长指标和饲料利用率指标,探讨乳酸菌与中药合生元在肉鸡生长和饲料利用率方面替代抗生素的优势.结果表明,试验组与对照组在生长性能和饲料利用率上各指标均差异不显著(P〉0.05),说明乳酸菌与中药合生元可以替代抗生素饲喂给肉仔鸡.  相似文献   
36.
37.
应用种子蛋白电泳图谱对高羊茅品种进行鉴别与聚类研究   总被引:2,自引:2,他引:0  
利用种子贮藏蛋白进行二二烷其磺酸钠-聚丙烯酰胺凝脉电泳,对23个高羊茅品种进行了 分析。表明该方法成本低,效率高,重复性好,能有效地反应高羊茅品种的遗传差异和亲缘关系。电泳谱带聚类分析所得到的类群,能代表生产上,饲用,草坪用类型以及两种用途中的主要生态类型。  相似文献   
38.
Engineering resistance against various diseases and pests is hampered by the lack of suitable genes. To overcome this problem we started a research program aimed at obtaining resistance by transfecting plants with genes encoding monoclonal antibodies against pathogen specific proteins. The idea is that monoclonal antibodies will inhibit the biological activity of molecules that are essential for the pathogenesis. Potato cyst nematodes are chosen as a model and it is thought that monoclonal antibodies are able to block the function of the saliva proteins of this parasite. These proteins are, among others, responsible for the induction of multinucleate transfer cells upon which the nematode feeds. It is well documented that the ability of antibodies to bind molecules is sufficient to inactivate the function of an antigen and in view of the potential of animals to synthesize antibodies to almost any molecular structure, this strategy should be feasible for a wide range of diseases and pests.Antibodies have several desirable features with regard to protein engineering. The antibody (IgG) is a Y-shaped molecule, in which the domains forming the tips of the arms bind to antigen and those forming the stem are responsible for triggering effector functions (Fc fragments) that eliminate the antigen from the animal. Domains carrying the antigen-binding loops (Fv and Fab fragments) can be used separately from the Fc fragments without loss of affinity. The antigen-binding domains can also be endowed with new properties by fusing them to toxins or enzymes. Antibody engineering is also facilitated by the Polymerase Chain Reaction (PCR). A systematic comparison of the nucleotide sequence of more than 100 antibodies revealed that not only the 3′-ends, but also the 5′-ends of the antibody genes are relatively conserved. We were able to design a small set of primers with restriction sites for forced cloning, which allowed the amplification of genes encoding antibodies specific for the saliva proteins ofGlobodera rostochiensis. Complete heavy and light chain genes as well as single chain Fv fragments (scFv), in which the variable parts of the light (VL) and heavy chain (VH) are linked by a peptide, will be transferred to potato plants. A major challenge will be to establish a correct expression of the antibody genes with regard to three dimensional folding, assembly and intracellular location.  相似文献   
39.
In the years 1973 and 1975 mosquitoes and some other Diptera (Tabanidae, Simuliidae, Hippoboscidae) were tested for virus. 13,924 mosquitoes, 75 horseflies and 60 blackflies were processed in 1973. Five strains of Tahyna virus were isolated from mosquito species Aedes vexans. 3,378 mosquitoes and 12 sheep keds were tested for virus in 1975. Twelve strains of Calovo virus were isolated from Anopheles maculipennis and one strain of Tahyna virus was obtained from Aedes vexans mosquitoes.  相似文献   
40.
邓敏  徐泽  张玲  胡翔 《西南园艺》2005,33(4):41-42
对HACCP作简要介绍,根据HACCP体系的要求,分析了机制针形名茶过程中各个环节可能出现的危害因素,用HACCP的原理确立了关键控制点,并且建立了相应的控制措施。  相似文献   
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