Coat protein polymerization of alfalfa mosaic virus strain VRU

The association behaviour of the coat protein of alfalfa mosaic virus strain VRU was studied by sedimentation analysis and electron microscopy. The results of this study were compared with the data obtained from similar studies with the coat protein of strain 425 (Driedonks et al., 1977). In the depolymerized state VRU protein is likely a dinier of the 24,050 molecular weight polypeptide chain. The main association product is a tubular structure with a diameter of about 180 Å. The optimum conditions for the reaction were polyphosphate-containing buffer at pH 6·5. Optical diffraction analysis of negatively stained specimens revealed a helical arrangement of the protein subunits in these assemblies. The same type of reaction product was found when the association reaction was carried out in the presence of polynucleotides. The length of the VRU particles is abnormally long compared to other alfalfa mosaic virus strains. This phenomenon can be ascribed to the tendency of the protein to polymerize into tubular rather than spherical particles.     

Increased Neopterin Levels in Brains of Patients with Human Immunodeficiency Virus Type 1 Infection

Postmortem levels of native neopterin (D-erythro-neopterin) were measured in cerebral cortical samples from 44 human immunodeficiency virus type 1-infected and eight uninfected, nonneurological control patients. Cerebral cortical gray and white matter neopterin levels for the controls ranged from 0.5 to 7.2 pmol/mg of protein in contrast to neopterin levels in brains of the virus-infected patients, which frequently were more than threefold and occasionally more than 30-fold higher than mean control levels. Cortical neopterin levels did not correlate with severity of the acquired immunodeficiency syndrome dementia complex, but subcortical levels correlated with the presence of active human immunodeficiency virus type 1 infection, as reflected by pathological evidence of multinucleated giant cell encephalitis. Evidence of opportunistic cytomegalovirus infections in approximately 25% of the human immunodeficiency virus type 1-infected patients was associated with enhanced levels of neopterin in frontal cortex.     

Rubus host range of rubus yellow net virus and its involvement with other aphid-borne latent viruses in inducing raspberry veinbanding mosaic disease

After graft inoculation with rubus yellow net virus (RYNV), 12 of 34 Rubus species and cultivars developed noticeable symptoms. R. macraei developed the most conspicuous symptoms and is recommended as an improved indicator plant. In attempts to determine the cause of raspberry veinbanding mosaic, a disease in which RYNV is involved, several European and North American red raspberry cvs were graft-inoculated with RYNV and three other aphid-borne viruses, black raspberry necrosis (BRNV), raspberry leaf mottle (RLMV) and raspberry leaf spot, singly and in all combinations. In periods of up to 4 yr, classical veinbanding mosaic symptoms developed in sensitive cvs only when they contained both RYNV and RLMV. These symptoms were intensified in plants co-infected with additional viruses. Veinbanding mosaic disease did not develop in any of 11 cvs infected with RYNV + BRNV, the combination of viruses previously assumed to be responsible for this disease in Britain and North America.     

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.     

Dissolution of Autographa californica nuclear polyhedrosis virus polyhedra by the digestive fluid of Trichoplusia ni (Lepidoptera:Noctuidae) larvae

The dissolution of polyhedra of Autographa californica nuclear polyhedrosis virus by digestive fluid collected from 5th stage Trichoplusia ni larvae was studied in vitro. Observations were made at timed intervals using phase contrast microscopy, and scanning and transmission electron microscopy. Dissolution occurred rapidly and in a detectable sequence. Under phase contrast, most polyhedra lost their refringence by 0.5 min. The polyhedra became rounded in appearance with small protuberances on the surface and Brownian movement was observed within. After 1 min, the envelope of most polyhedra had ruptured, releasing the enclosed virions. The protuberances were also observed under the scanning electron microscope after digestion for 0.5 min. Many shell fragments devoid of internal contents were seen after more lengthy digestion. Internal structural changes were revealed by electron microscopy. After 1 min of exposure, polyhedra were observed in all stages of dissolution. By 3 min, only virions, scattered about in heterogeneous material, could be distinguished.     

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.     

Biotechnological challenges of bioartificial kidney engineering

With the world-wide increase of patients with renal failure, the development of functional renal replacement therapies have gained significant interest and novel technologies are rapidly evolving. Currently used renal replacement therapies insufficiently remove accumulating waste products, resulting in the uremic syndrome. A more preferred treatment option is kidney transplantation, but the shortage of donor organs and the increasing number of patients waiting for a transplant warrant the development of novel technologies. The bioartificial kidney (BAK) is such promising biotechnological approach to replace essential renal functions together with the active secretion of waste products. The development of the BAK requires a multidisciplinary approach and evolves at the intersection of regenerative medicine and renal replacement therapy. Here we provide a concise review embracing a compact historical overview of bioartificial kidney development and highlighting the current state-of-the-art, including implementation of living-membranes and the relevance of extracellular matrices. We focus further on the choice of relevant renal epithelial cell lines versus the use of stem cells and co-cultures that need to be implemented in a suitable device. Moreover, the future of the BAK in regenerative nephrology is discussed.     

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.