Relating cistrons and functions in bacteriophage PM2

An approach to correlate functions with cistrons in bacteriophage PM2 is presented. Two of the temperature-sensitive mutants obtained differed from the wild type in heat sensitivity and four differed in host range. Comparison of the electrophoretic patterns of DNA from cells infected at the restrictive temperature with those obtained in wildtype infection revealed that viral DNA bands were absent with three additional mutants. Complementation analysis assigned the four host range mutants to cistron I and the three mutants defective in DNA synthesis to cistron IV. Recombination frequencies were used to locate cistrons III and IV on the partial genetic map of PM2.     

Mapping of the influenza virus genome II. Identification of the P1, P2, and P3 genes

Polyacrylamide gel electrophoresis of the RNAs of influenza A viruses was performed under conditions in which each of the eight RNA segments of influenza A/PR/8/34 (H0N1) virus migrates differently from the equivalent segments of influenza A/Hong Kong/8/68 (H3N2) virus. As reported previously [Palese, P. and Schulman, J. L. Proc. Nat. Acad. Sci. USA73, 2142–2146 (1976)], analysis of RNA patterns of recombinant viruses derived from these two parents permitted the identification of the fourth RNA segment (the slowest-moving RNA segment is counted as #1) of each virus as the gene coding for hemagglutinin, and the fifth segment of Hong Kong virus and the sixth segment of PR8 virus as the genes for the respective neuraminidases. Three more genes have been identified by correlating migration patterns of RNAs with protein patterns of recombinant viruses on gradient polyacrylamide gels. The slowest-moving band (RNA 1) is the gene coding for the third largest influenza virus protein (P3). RNA segment 2 codes for the largest protein (Pl), and the P2 protein is coded for by RNA segment 3.     

Distribution of radioactive cortisol in the tissues and media of the eye

Incorporation of cortisol-³H and the dynamics of its accumulation in the tissues and media of the eye (sclera, ciliary body, cornea, iris, capsule of the lens, aqueous humor, vitreous body) were investigated. The intensity of incorporation of cortisol into the tissues and media of the eye and also the rate of its elimination from them were shown to differ. The sclera, cornea, ciliary body, and the capsule of the lens were shown to be target tissues for cortisol.Moscow Helmholtz Scientific-Research Institute of Eye Diseases. (Presented by Academician of the Academy of Medical Sciences of the USSR S. S. Debov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 4, pp. 401–402, April, 1977.     

Purification and characterization of potyvirus helper component

Helper component (HC) was purified from tobacco vein mottling (TVMV)- and potato virus Y (PVY)- infected tobacco plants by sucrose gradient fractionation followed by affinity chromatography on oligo(dT)-cellulose and by gel electrophoresis. The subunit apparent molecular weights (M(r)) of the purified HCs were 53,000 (53K) and 58K for TVMV and PVY, respectively. Antisera to these purified polypeptides specifically blocked the activity of the homologous HC, as determined by aphid transmission assays, and specifically precipitated 75K products of the cell-free translation of the homologous RNA. The molecular weight of undissociated, biologically active TVMV or PVY HC, as determined by high-pressure liquid chromatography (HPLC)-gel permeation chromatography was found to be between 100K and 150K, suggesting that the active molecule is a dimer.     

Respiratory syncytial virus glycoproteins

The proteins of respiratory syncytial (RS) virus were analyzed by SDS-polyacrylamide gel electrophoresis. Eight virion structural proteins with molecular weights of 180,000, 89,000, 48,000, 42,000, 34,000, 28,000, 25,000, and 21,000 were identified. These proteins were given tentative designations of L (180,000), G (89,000), F1 (48,000), NP (42,000), P (34,000), M (28,000), Vp25 (25,000), and F2 (21,000). The 89,000-, 48,000-, and 21,000-dalton polypeptides were glycosylated and could be purified on lentil-lectin sepharose columns. All three glycoproteins could be immunoprecipitated from extracts of infected cells but not from uninfected cells, suggesting that they are viral specified. The host cell affected the apparent molecular weights of the largest and smallest glycosylated polypeptides possibly by differences in glycosylation. The 48,000- and 21,000-dalton glycopolypeptides were disulfide linked subunits of a 68,000-dalton glycoprotein that was seen on unreduced gels. The 68,000-dalton glycoprotein was thus similar to the fusion (F) protein of paramyxoviruses. Treatment of infected cultures with tunicamycin, a drug that blocks glycosylation, inhibited syncytial formation and resulted in over a 1000-fold reduction of extracellular infectious virus. Virions purified from tunicamycin-treated cells had reduced amounts of all three glycosylated proteins. No new forms of these proteins were conclusively identified, suggesting that unglycosylated forms of RS glycoproteins were not incorporated into virion membranes.     

Systematic isolation of transducing phages for Myxococcus xanthus.

Six new phages active on Myxococcus xanthus have been isolated from cultures of myxobacteria. The six are all capable of transduction, and they fall into three groups. Members of one group have long contractile tails, have a characteristic neutralization antigen, and resemble the previously described M×4. Members of a second group, exemplified by M×8, have very short tails and a characteristic antigen. M×9, the sole member of the third group, has a very short tail and a characteristic antigen. Phage M×8, which is active on fruiting as well as nonfruiting strains of M. xanthus, can transduce auxotrophic, antibiotic resistance and motility markers in M. xanthus. Although crude lysates of M×8 contain 58-nm diameter particles with a tail and 29-nm particles without tail, only 58-nm particles can form plaques and transduce. The plaque-forming particles of M×8 possess a single DNA molecule of 56,000 base pairs with a buoyant density of 1.726 g/cm³, virtually identical to that of the DNA from its host.     

A cell-free model of the encephalomyocarditis virus-induced inhibition of host cell protein synthesis.

When preincubated extracts from Krebs-II cells were supplemented with total poly(A)-containing RNA isolated from encephalomyocarditis virus-infected Krebs-II cells, two phenomena characteristic of EMC virus infection of these cells in vivo were observed: (i) preferential translation of viral rather than cellular, mRNA, and (ii) a general inhibition of protein synthesis, relative to the synthesis in samples where the poly(A)-containing RNA from uninfected cells served as the template. The first effect could not be explained by an irreversible functional inactivation of cellular templates and seemed to result from a direct interference of viral RNA with the translation of cellular mRNA. The second effect was due primarily to the presence of double-stranded RNA.     

An immunochemical investigation of SV40 T antigens. 1. Production properties and specificity of rabbit antibody to purified simian virus 40 large-T antigen.

Large quantities of a species of T antigen with an apparent molecular weight of 84,000 have been isolated from monkey kidney cells infected with SV40 by using the protein A Antibody Adsorbent (P.A.A.) technique and preparative SDS-polyacrylamide gel electrophoresis. The purified polypeptide was found to be immunogenic, inducing a specific antibody response in a rabbit. The resulting antiserum was 10 times as potent as a hamster anti-tumor serum and reacted with native as well as SDS- and DTT-treated T antigens from SV40-transformed or lytically infected cells. It failed to show any reaction with T antigen from polyoma-infected cells and showed similar specificity to antitumor serum obtained from hamsters which had been inoculated with cells of an SV40-transformed, virus-free cell line. In both cases two distinct polypeptides, large T (84,000 and 94,000) and small t (19,000) were precipitated from extracts of SV40-transformed or lytically infected cells. The rabbit antiserum was shown to be capable of specifically precipitating small-t antigen in the absence of large-T antigen and therefore these two polypeptides must share common antigenic determinants. A radioimmunoassay showed large-T antigen to be very heat stable in direct contrast to earlier results obtained using the complement fixation test. The reasons for this discrepancy and its functional significance are discussed.     

Study of the HLA system in Burkitt's lymphoma

Seventy-eight patients with Burkitt's lymphoma and seventy controls from Ghana were typed for HLA-A, B, C and DR antigens, to determine whether there is an association between the HLA system and Burkitt's lymphoma. Increased relative risk was observed in Burkitt's lymphoma patients with DR7, HLA-A1 and B12 (BW44).     

Chromosome abnormalities in chronic lymphocytic leukemia revealed by TPA as a mitogen

Bone marrow and peripheral blood cultures of chronic lymphocytic leukemia patients were mitogenically stimulated with TPA (12-0-tetradecanylphorbol-13-acetate). Clonal cytogenetic abnormalities were detected in frequencies varying from 15% to 100%, in five of the six patients studied. Parallel studies with pokeweek mitogen showed a much lower level of stimulation and only two abnormal clones were detected. The chromosome abnormalities described in this study are similar to those reported in CLL by other authors, particularly with respect to trisomy 12 and deletion 11q. A significant frequency of hypodiploidy and chromosome deletion was also detected in this study, and further studies are underway to determine the significance of these findings.