中国甘薯病毒的血清学检测

 作者用4种甘薯病毒抗体(IgG),3种血清学方法(DAS-ELISA、Dot-blot-ELISA和ISEM)对北京,江苏、四川、山东四省(市)的253份甘薯病毒病样品进行了检测。结果表明:上述地区甘薯中普遍存在甘薯羽状斑驳病毒(SPFMV)和甘薯潜隐病毒(SPLV),尚难确定是否存在甘薯轻斑驳病毒(SPMMV)和甘薯花叶菜花叶状病毒(Sweet Potato Caulimo-like Virus,SPCLV)。21%的显症样品同上述4种病毒的抗血清不产生反应,显示我国甘薯上尚存在其它病毒。用Dot blot-ELISA和ISEM检测甘薯病毒比用DAS-ELISA灵敏准确。     

PR—1a蛋白基因的克隆及序列分析

以珊西烟草（Nicotina tabacum cv. Xanthi-nc）的基因组DNA为模板，通过合成一对特异性引物，利用多聚酶链式反应（PCR）扩增获得PR－1a蛋白基因。将其克隆到E.coli质粒上进行序列分析。结果表明：该基因由504个碱基组成，编码168个氨基酸。与已发表序列相比较，核苷酸序列及推导出的氨基酸序列的同源性分别为99.9%和100％。     

甘薯羽状斑驳病毒单克隆抗体研制成功

甘薯羽状斑驳病毒(Sweet Potato Feath-ery Mottle Virus,SPFMV)可随甘薯传播,并可蚜传。在世界甘薯产区广泛流行。往往和其它病毒、类菌原质体及某些飞虱传致病因子共侵染引致甘薯矮化、花叶、丛枝、块根外部裂纹、块根内部木栓等症状,在某些国家和地区造成甘薯     

Ecological forecasts: an emerging imperative

Planning and decision-making can be improved by access to reliable forecasts of ecosystem state, ecosystem services, and natural capital. Availability of new data sets, together with progress in computation and statistics, will increase our ability to forecast ecosystem change. An agenda that would lead toward a capacity to produce, evaluate, and communicate forecasts of critical ecosystem services requires a process that engages scientists and decision-makers. Interdisciplinary linkages are necessary because of the climate and societal controls on ecosystems, the feedbacks involving social change, and the decision-making relevance of forecasts.     

Global trajectories of the long-term decline of coral reef ecosystems

Degradation of coral reef ecosystems began centuries ago, but there is no global summary of the magnitude of change. We compiled records, extending back thousands of years, of the status and trends of seven major guilds of carnivores, herbivores, and architectural species from 14 regions. Large animals declined before small animals and architectural species, and Atlantic reefs declined before reefs in the Red Sea and Australia, but the trajectories of decline were markedly similar worldwide. All reefs were substantially degraded long before outbreaks of coral disease and bleaching. Regardless of these new threats, reefs will not survive without immediate protection from human exploitation over large spatial scales.     

Experimental infection of 3-week-old conventional colostrum-fed pigs with porcine circovirus type 2 and porcine parvovirus

This report describes an experimental infection with porcine circovirus type 2 (PCV2) in combination with porcine parvovirus (PPV) in 3-week-old conventional colostrum-fed pigs with maternal antibodies to both viruses. Two groups of four pigs each were inoculated with PCV2 and PPV. One of the groups received also a commercial inactivated vaccine against porcine pleuropneumonia to evaluate possible effects of the stimulation of the immune system of pigs on the infection. Another group of four pigs was kept as uninfected control. Clinical signs, rectal temperatures and body weights were recorded. Serum antibody titers to PCV2 and PPV were determined at weekly intervals. Pigs were killed 42 days after inoculation and tissue samples were examined for the presence of gross and microscopic lesions. Tissues were also analyzed for the presence of PCV2 and PPV DNA by PCR, and for the presence of PCV2 antigen by immunohistochemistry (IHC). All the pigs had serum antibodies to PCV2 and PPV at the beginning of the trial. None of them developed clinical symptoms or pathological lesions typical of post-weaning multisystemic wasting syndrome (PMWS), a disease associated to PCV2 infection. However, IHC and/or PCR analyses showed that clinically silent PCV2 infection developed in five of the eight inoculated pigs, regardless of the administration of the vaccine. In particular, PCV2 DNA and/or antigen were detected in most of the tissues examined in the two pigs with the lowest titer of maternal PCV2 antibodies at the beginning of the trial. PPV DNA was not detected in any of the samples examined. The five pigs with PCR and/or IHC evidence of PCV2 infection had a mean weight gain during the experiment lower than that of the inoculated PCR-negative pigs considered together and that of the control pigs. In conclusion, it would appear that passive immunity against PCV2 can play a role in preventing the development of PMWS, but is not able to prevent the establishing of clinically silent PCV2 infections. The dissemination and persistence of the virus in the tissues may depend on the level of PCV2 antibodies at the time of inoculation.     

Active oxygen detoxifying enzymes and phenylalanine ammonia-lyase in the ethylene-induced chilling tolerance in citrus fruit

The effects of applying ethylene (2 microL x L(-)(1)) during cold storage of Fortune mandarins on the development of chilling-induced peel damage and on changes in the activities of the enzymes of the antioxidant system, superoxide dismutase, catalase (CAT), ascorbate peroxidase, guaiacol peroxidase, and glutathione reductase, and on phenylalanine ammonia-lyase (PAL) have been investigated. Chilling damage was reduced by applying ethylene during fruit storage at 1.5 degrees C. PAL activity increased in response to cold stress and was higher in fruit held under ethylene than under air during the whole storage period, whereas CAT was temporarily higher in ethylene-treated fruit. In contrast, the activities of the other enzymes were not increased by ethylene. The global results suggest that the ethylene-induced chilling tolerance in Fortune mandarins might be due to increased PAL and CAT activities.     

甘薯病毒病的研究Ⅰ甘薯羽状斑驳病毒的分离、鉴定

本文从寄主范旧,蚜传特性、病毒颗粒形态、免疫电镜等方面对嫁接获得的甘薯羽状斑驳病毒廊坊分离物(SPFMV—LF)进行了鉴定,并和SPFMV—RC(美国株)进行了实验比较。SPFMV—LF易汁液摩擦传播和嫁接传播,并以蚜虫非持久性传播,SPFMV—LF系统侵染巴西牵牛(Ipomoea setosa)、牵牛(I.nil);不侵染Chenopodium quinoa、C.ama-ranticolor、Nicotiana benthamiana及其它烟草。尚未发现其局部斑寄主。SPFMV—LF及SPFMV—RC感染I.setosa后引起相似的症状,但感染I.nil后症状差别较大。病毒颗粒长860—830nm,经两次蔗糖垫超速离心从SPFMV—LF感染的I.setosa叶片提取病毒并在BALB/C小鼠中制备抗SPFMV—LF的腹水多克隆抗体,免疫电镜表明,SPFMV—LF的抗体和SPFMV—RC株系有反应。上述实验结果表明SPFMV—LE是SPFMV的一个株系,但不同于SPFMV—RC。     

北京引致大丽菊花叶症的三种病毒

 大丽菊(Dahlia pinnata Cav.)花叶病已成为花卉生产出口的严重障碍。作者于1986-1987年在表现花叶的北京大丽菊上分离到两种形态大小不同的病毒分离物,电镜检测到一直径较大的球形病毒,分别定为BDM-1、BDM-2和BDM-3。经寄主反应、体外抗性、粒体形态、血清学等鉴定,病毒分离物BDM-1是黄瓜花叶病毒CMV;BDM-2是烟草花叶病毒TMV;BDM-3是大丽菊花叶病毒DaMV。从寄主反应、粒体大小、衣壳蛋白氨基酸组份及沉降特性综合分析看,BDM-1可能是CMV的另一株系CMV-DP。