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J Korb

Publications and source records attributed to J Korb.

At least 19 recordsLinked to original sources
PubMed1990

Binding properties of avian retroviral proteins. I. Preparation and basic characterization of ASLV NC(p12) and MA(p19).

Using SP-Sephadex column chromatography we isolated from an avian retrovirus, AMV(MAV), nucleic acid-binding proteins ASLV NC(p12) and MA(p19). As shown by several criteria, namely SDS-PAGE, PR(p15) protease activity, and nucleic acid binding assay with the use of both ss and ds DNAs, our NC(p12) and MA(p19) isolates are virtually pure proteins mutually not cross-contaminated. Rabbit anti-NC(p12) and anti-MA(p19) sera which we prepared did not cross-react mutually. We conclude that both NC(p12) and MA(p19) and antibodies against them are adequately pure preparations for investigating their nucleic acid binding specificities towards AMV(MAV) genomic RNA and MAV-1 proviral DNA using electron microscopy supported by computer analysis of electron micrographs.

Animals↗
PubMed1990

Binding properties of avian retroviral proteins. II. Binding of protein ASLV NC(p12) to viral RNA and proviral DNA.

Binding of the major avian retroviral nucleocapsid protein ASLV NC(p12) to the MAV-1 (myeloblastosis-associated virus) proviral dsDNA and viral ssRNA was analysed using electron microscopy. Specificity of the binding was estimated by special computer programs. The NC(p12) protein bound to MAV-1 proviral dsDNA (clone pAT153--MAV-1), but specificity of this binding was not found by computer evaluation. NC(p12) also bound to nondenatured 70S viral RNA at a rate of 25 +/- 3 molecules per RNA molecule. When this RNA was denatured either before or after the complexing, it showed no binding affinity for the protein. This result implies that preserved secondary structure of the viral RNA was required for the binding.

Animals↗
PubMed1990

Binding properties of avian retroviral proteins. III. Binding of protein ASLV MA(p19) to viral RNA and proviral DNA.

The binding of the avian retroviral matrix protein ASLV MA(p19) to homologous viral ssRNA and proviral dsDNA was analysed using electron microscopic methods combined with a special computer evaluation. No binding affinity of MA(p19) to homologous nondenatured or denatured viral RNA was found. In contrast, ASLV MA(p19) was shown to have one specific binding site on MAV-1 proviral dsDNA at position 6795 +/- 345 bp from the 5' end of the molecule. A second specific binding site was found in a cellular sequence.

Animals↗
PubMed1989

[Non-imported conjunctivitis with detection of Chlamydia trachomatis].

The authors describe conjunctivitis caused by Chlamydia trachomatis. The diagnosis was established by isolation on tissue cultures with a typical finding of intracytoplasmatic inclusions. Serum antibodies were slightly elevated, the complement binding reaction was 1:16, ELISA 1:64. From the clinical aspect trachoma was not involved. The patient was not in contact with foreigners from endemic areas. The disease was cured only after general administration of Tetracycline. The authors maintain that the diagnosis and prevention of ocular Chlamydia infections in adults and neonates should be extended.

Chlamydia trachomatis↗
PubMed1978

Size and secondary structure of avian myeloblastosis virus associated ribosomal RNA: comparison with cellular and precursor ribosomal RNA.

Ribosomal RNA isolated from ribosomes present inside avian myeloblastosis virus (AMV) was characterized by electron microscopy using the formamide-urea spreading technique. The molecular weight and the secondary structures were compared with those of r-RNA and precursor r-NA isolated from host cells, the leukemic myeloblasts. The molecular weight of viral r-RNA (1.62 +/- 0.18 X 10(6) and 0.69 +/- 0.10 X 10(6)) and the molecular weight of cellular r-RNA (1.63 +/- 0.18 X 10(6) and 0.67 +/- 0.09 X 10(6)), the latter obtained from avian myeloblasts, were found to be identical and comparable with the molecular weight of chicken liver r-RNA. Likewise, the secondary structures of viral r-RNA were identical to those of cellular r-RNA. The postulated possible precursor character of viral r-RNA was excluded, since the molecules of viral r-RNA do not show any similarity to those of precursor r-RNA. Previously observed differences in behavior of viral and cellular (myeloblastic) r-RNA in sedimentation and electrophoretic mobility are discussed.

Animals↗
PubMed1977

Electron microscopy of the segmented RNA genome ofLa Crosse virus: absence of circular molecules.

The three species of single-stranded RNA present in La Crosse virus were examined in the electron microscope. Because large amounts of contaminating cellular DNA are copurified with the virus despite extensive attempts to purify the virus, it was necessary to use procedures that eliminated the bulk of this DNA before the viral RNA was analyzed. When this was done, the modal lengths of La Crosse virus RNA were 0.4, 2.0, and 3.1 mum. These lengths correspond well to their known molecular weights of 0.4 x 106, 1.8 x 106, and 2.9 x 106. Under the denaturing conditions used to permit complete spreading of these single-stranded RNA molecules, no single-stranded circular molecules are observed. Therefore, the circular nucleocapsids present in La Crosse virus and some other bunyaviruses do not appear to be due to convalent linkage of the ends of the RNA genome.

Cell Line↗
PubMed1977

Electrophoretic analysis of the molecular weight of murine mammary tumor virus RNA.

Molecular weight determinations of native and subunit RNAs of murine mammary tumor virus (MuMTV), a type B oncornavirus, were performed by polyacrylamide gel electrophoresis and compared with molecular weights of well-characterized avian cellular RNAs and tobacco mosaic virus RNA. From extrapolations of semilog plots of the molecular weights of the standard RNAs versus relative electrophoretic mobilities and Ferguson plots, the subunit and native RNAs of MuMTV were found to possess molecular weights of 2.93 X 10(6) and 6.45 X 10(6), respectively. These data support the assumption that two subunit molecules comprise the native RNA of MuMTV.

Animals↗
PubMed1976

The oncornavirus maturation process: quantitative correlation between morphological changes and conversion of genomic virion RNA.

Avian myeloblastosis virus (AMV) was harvested at different time intervals from chick leukemic myeloblasts, and the rate of the maturation process of AMV was estimated on the basis of morphological changes in the virions and conversion of genomic viral RNA. The change from immature virions characterized by the presence of an electronlucent center to the condensed mature form (with dense nucleoid) was accompanied by the conversion of 30-40S RNA to 60S RNA. Both processes were quantitatively defined, correlated, and found to proceed in parallel at the same speed. Early stages of maturation were characterized by a high turnover of immature to mature virions; 31-40% of the mature forms were found in 3.5-min virus harvests. The rate of this process decreased with time. The 17-hour harvests still revealed the presence of 10-15% of immature virions. The course of the maturation process is discussed.

Animals↗