Further properties of wineberry latent virus and evidence for its possible involvement in calico disease

The flexuous filamentous particles of wineberry latent virus (WLV) were found to measure 620. 12 nm and not 510. 12 nm as previously reported. Analysis of dsRNA from infected plants detected a major species of c. 5.7. 10⁶ mol. wt and minor species of lower mol. wt. Purified virus particles formed a major and a minor buoyant density component in solutions of caesium salts with densities of 1.26 and 1.25 g cm^-3 in Cs₂SO₄ and 1.30 and 1.29 g cm^-3 in CsCl. The particles contained a single nucleic acid species, presumably single stranded RNA, and a single polypeptide of estimated mol. wt 2.78. 10⁶ and 31 000 respectively. In indirect ELISA, purified particles of WLV and particles in plant sap failed to react specifically with antiserum to nine carlaviruses, 12 potexviruses, three capilloviruses or apple chlorotic leafspot closterovirus, nor was WLV found to react with several of these antisera in immunosorbent electron microscopy or immunoblots. In Marion and Olallie blackberry, WLV in mixture with raspberry bushy dwarf virus (RBDV), but not RBDV alone, induced veinal line-pattern symptoms resembling those of calico disease reported from the USA.     

High resolution two-dimensional gel electrophoresis of the proteins and glycoproteins of human blood platelets and platelet membranes

The proteins and glycoproteins of human blood platelets and platelet membranes in both the reduced and the unreduced states have been analysed by isoelectric focusing and sodium dodecyl sulphate-discontinuous polyacrylamide gel electrophoresis in a two-dimensional technique. Gels which had been stained with periodic acid-Schiff's reagent could be counter-stained with Coomassie Brilliant Blue, simplifying the recognition of components which stain with both reagents. The major glycoproteins and some of the proteins have been identified and the characteristics of the membrane and of the whole platelet components established in this system.     

Antimetabolic activities of 2-fluoro-L-histidine.

2-Fluoro-L-Histidine inhibits protein synthesis in various cell cultures, as measured by ³H-leucine incorporation. This histidine analog also inhibits the cytopathogenicity of a number of RNA and DNA viruses in primary and continuous cell cultures; it blocks the transformation of normal mouse (MO) cells by murine sarcoma virus, and partially suppresses the release of murine leukemia virus by a continuously infected mouse cell line (JLSV5). In human skin fibroblasts, it reduces the interferon-inducing capacity of poly(I)·poly(C). Inhibition of cell protein synthesis may be the common cause of the various effects. 4-Fluoro-L-histidine is essentially inert in all of the test systems examined.     

From Virus Research to Molecular Biology: Tobacco Mosaic Virus in Germany, 1936-1956

In 1937, a group of researchers in Nazi Germany began investigating tobacco mosaic virus (TMV) with the hope of using the virus as a model system for understanding gene behavior in higher organisms. They soon developed a creative and interdisciplinary work style and were able to continue their research in the postwar era, when they made significant contributions to the history of molecular biology. This group is significant for two major reasons. First, it provides an example of how researchers were able to produce excellent scientific research in the midst of dictatorship and war.Coupled with the group's ongoing success in postwar Germany, the German TMV investigators provide a dramatic example of how scientific communities deal with adversity as well as rapid political and social change. Second, since the researchers focused heavily (though no exclusively) on TMV, their story allows us to analyze how an experimental system other than phage contributed to the emergence of molecular biology.     

Nucleoli and Stress Granules: Connecting Distant Relatives

Nucleoli and cytoplasmic stress granules (SGs) are subcellular compartments that modulate the response to endogenous and environmental signals to control cell survival. In our opinion, nucleoli and SGs are functionally linked; they are distant relatives that combine forces when cellular homeostasis is threatened. Several lines of evidence support this idea; nucleoli and SGs share molecular building blocks, are regulated by common signaling pathways and communicate when vital cellular functions become compromised. Together, nucleoli and SGs orchestrate physiological responses that are directly relevant to stress and human health. As both compartments have established roles in neurodegenerative diseases, cancer and virus infections, we propose that these conditions will benefit from therapeutic interventions that target simultaneously nucleoli and SGs.      

马传染性贫血病毒基因非编码区LTR嵌合克隆的构建

在已有全长感染性克隆pLGFD3-8和pD70344的基础上,根据马传贫弱毒疫苗致弱过程中不同代次毒株LTR序列的分析,在LTR U3区选取特定的酶切位点对EIAV非编码区LTR基因进行了部分替换.将替换的全基因克隆转染驴胎皮肤细胞(FDD)并以驴白细胞(DL)传代,用逆转录酶活性检测、RT-PCR方法及Real-time RT-PCR验证其感染性.结果发现,其衍生病毒感染上述两种细胞均出现明显的细胞病变;细胞培养上清可检测到RT酶活性和RT-PCR阳性.电镜下可见大量典型的EIAV颗粒.pLGFD9-12嵌合克隆衍生病毒与其父本克隆衍生病毒pLGFD3-8具有相似的复制水平,pLGFD9-12嵌合克隆衍生病毒在DL细胞上复制水平略高于FDD细胞.此结果为进一步深入研究LTR对马传染性贫血病毒复制水平和毒力的影响奠定了基础.     

Effects of aphidicolin on retrovirus DNA synthesis in vivo

Renaturation of $\text{Aequorea}$ green-fluorescent protein (A-GFP) was achieved for the first time following denaturation in guanidine-HCl or acid. Denaturation was accompanied by the concerted loss of visible fluorescence, alteration of absorption characteristics, and large negative deflection of CD signal in the far UV. Dialysis of a guanidine-denatured sample at pH 8 resulted in 64% renaturation (return to native absorption) and neutralization of an acid-denatured sample restored 90% of the native absorption. Renatured GFP is highly fluorescent and indistinguishable from native GFP with respect to the shape of excitation and emission spectra. Both native and denatured proteins exhibit resistance to trypsin hydrolysis and have identically broad pH and heat stability profiles, all of which suggest full renaturation.