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.     

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.     

Nocturnal penile tumescence as a biologic marker in assessing erectile dysfunction

Recent findings challenge the belief that most cases of impotence are psychogenic. Research indicates that nocturnal penile tumescence (NPT) can be viewed as a biologic marker for physiologic erectile capacity. Thus, the test can help to distinguish between physicogenic and psychogenic impotence. To determine proximal causes of erectile failure, other evaluations are easily performed during NPT monitoring.     

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.     

Lymphoma arising in an adenolymphoma

A malignant lymphoma that originated in association with an adenolymphoma (Warthin's tumor) of the parotid salivary gland is reported. The occurrence of lymphomas in salivary glands is discussed briefly.     

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.