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J Nosek

Publications and source records attributed to J Nosek.

At least 37 records · Page 2Linked to original sources
PubMed1994

NADH dehydrogenase subunit genes in the mitochondrial DNA of yeasts.

The genes encoding the NADH dehydrogenase subunits of respiratory complex I have not been identified so far in the mitochondrial DNA (mtDNA) of yeasts. In the linear mtDNA of Candida parapsilosis, we found six new open reading frames whose sequences were unambiguously homologous to those of the genes known to code for NADH dehydrogenase subunit proteins of different organisms, i.e., ND1, ND2, ND3, ND4L, ND5, and ND6. The gene for ND4 also appears to be present, as judged from hybridization experiments with a Podospora gene probe. Specific transcripts from these open reading frames (ND genes) could be detected in the mitochondria. Hybridization experiments using C. parapsilosis genes as probes suggested that ND genes are present in the mtDNAs of a wide range of yeast species including Candida catenulata, Pichia guilliermondii, Clavispora lusitaniae, Debaryomyces hansenii, Hansenula polymorpha, and others.

Amino Acid Sequence↗
PubMed1993

Isolation of a dsRNA virus from Dipodascus (Endomyces) magnusii.

Virus-like particles (VLPs) of 40 nm diameter were isolated from the yeast-like fungus Dipodascus magnusii. These VLPs copurify with several linear double-stranded RNA molecules of different size. We have found some polymorphism in both the length and the number of these dsRNAs among six D. magnusii strains. Analysis of CsCl gradient-purified VLPs on PAGE/SDS electrophoresis showed one major protein component with an apparent molecular weight of 75 kDa.

Fungi↗
PubMed1989

Unusual stage-specific embryonic antigen (TEC-4) defined by a monoclonal antibody to embryonal carcinoma cells defective in the expression of embryoglycan.

Most developmentally regulated epitopes identified on embryonal carcinoma cells and murine preimplantation embryos are associated with a glycoprotein-bound large glycan called embryoglycan. To prepare monoclonal antibodies recognizing other, less immunogenic stage-specific embryonic epitopes, we used embryoglycan-negative embryonal carcinoma cells P19XT.1.1 as immunogen. One monoclonal antibody prepared by this strategy was found to react specifically with mouse embryonal carcinoma and embryo-derived stem cell lines. The target epitope, TEC-4, was found to be expressed on eggs and two-cell embryos but was undetectable on later stages of mouse embryos and adult mouse tissues. NaDodSO4/PAGE of immunoaffinity-isolated antigen revealed that TEC-4 epitope is associated with glycoproteins of apparent Mr 120,000 and 240,000. The epitope was resistant to oxidation by sodium periodate and to digestion by endoglycosidase F but was sensitive to treatment with protein-denaturing agents and proteases, which suggested that the epitope is located in the protein moiety of the molecule. In the course of retinoic acid-induced differentiation of embryonal carcinoma cells the epitope disappeared before the onset of morphological differentiation. The combined data indicate that TEC-4 is an unusual stage-specific embryonic antigen that may be amenable to direct genetic analysis.

Animals↗
PubMed1988

Inhibition of adhesion of F9 embryonal carcinoma cells to substratum by a novel monoclonal antibody, TEC-05, reactive with a developmentally regulated carbohydrate epitope.

Embryonal carcinoma cells carry on their surfaces carbohydrate antigens that are also expressed in early embryonic cells. We report here the expression and properties of a new developmentally regulated carbohydrate epitope, which is defined by a monoclonal antibody TEC-05. This antibody was generated by immunization of a rat with mouse embryonal carcinoma cells P19S1801A1. By immunofluorescence, the TEC-5 epitope was first detected on 8-cell-stage mouse embryos and was present on all subsequent stages of preimplantation development. Absorption analysis revealed that TEC-5 epitope was expressed only on a limited number of adult mouse tissues. In the direct radioantibody binding assay, TEC-05 reacted strongly with OTF9-63 cells and with some of the mouse embryonal carcinoma cell lines tested. Its reaction with differentiated cell lines was weak or undetectable. In the course of differentiation of OTF9-63 cells induced by retinoic acid, the epitope disappeared with the onset of morphological differentiation. The binding of the antibody to OTF9-63 cells was inhibited to 50% by 10-50 microM N-acetyllactosamine and lactose. Immunolabelling of extracts from OTF9-63 cells separated by sodium-dodecyl-sulfate (SDS) polyacrylamide gel electrophoresis revealed that TEC-5 epitope was carried by high-molecular-weight glycoconjugates (molecular weight greater than 100,000). Molecules, isolated from [3H]-fucose-labelled OTF9-63 cells by indirect immunoprecipitation with TEC-05 antibody, were degraded by extensive pronase digestion or mild alkaline treatment to large carbohydrate chains that were excluded from a Sephadex G-50 column. Direct evidence that TEC-05 antibody bound to embryoglycan was obtained using a modified Farr's assay. The antibody was found to inhibit adhesion of F9 and OTF9-63 cells to substratum. The inhibitory effect, which could be abrogated by lactose, seemed to be specific, because another IgM monoclonal antibody which also binds to embryoglycan had no effect. Combined data indicated that TEC-05 antibody recognizes a carbohydrate epitope which is involved in cell-substratum adhesion of F9 cells and which provides a new marker for structure-function studies of stage-specific embryonic antigens.

Animals↗
PubMed1987

Quantitative estimation of HLA-A and HLA-B antigens carrying the Bw4 supertypic specificity in human peripheral blood lymphocytes.

A monoclonal antibody specific for HLA-Bw4 was employed for the quantitative estimation of class I antigens on human peripheral blood lymphocytes and on the human macrophage cell line U 937. The epitopes reactive with the HLA-Bw4-specific antibody, which are present on different antigens coded by the HLA-A or the HLA-B locus, were characterized in terms of equilibrium and kinetic binding parameters. The level of expression of class I antigens on human lymphocytes was found to be in direct proportion to the gene dose. Variations between donors of the same phenotype were of minor importance. Estimation of the association constant, association rate constant, and half-life of dissociation for the interaction of the antibody with lymphocytes heterozygous for either HLA-A24, HLA-A32, HLA-A9, or HLA-Bw4 strongly suggested that the public antigenic determinant shared by these antigens is identical.

Antibodies, Monoclonal↗
PubMed1986

Studies on the ecology of tick-borne encephalitis virus in the Carpathian and Pannonian types of natural foci.

During the years 1972-1982, the role of Ixodes ricinus ticks was studied as vectors of tick-borne encephalitis (TBE) virus in the Carpathian and Pannonian types of natural foci. The proportion of TBE virus-infected Ixodes ricinus ticks in the Carpathian elementary foci varied from 0.37 to 4.1 per cent, while in the Pannonic elementary foci it ranged from 0.07 to 6 per cent, respectively. TBE virus was isolated from organs of small rodents in both the Carpathian and Pannonian types of natural foci. A correlation was established between the percentage of infected ticks and the proportion of seropositive inhabitants.

Animals↗
PubMed1986

Peculiarities of tick-borne encephalitis virus reproduction in Haemaphysalis inermis ticks and their explants.

Virological, electron microscopic and immunomorphological investigation on the reproduction of tick-borne encephalitis (TBE) virus in Haemaphysalis inermis ticks and in tissue explants from nymphs during their metamorphosis revealed that the virus reproduced in the cells of different tissues and organs of ticks which were in different phases and stages of life cycle. During the eclipse phase of TBE virus persistence in ticks, when no virus could be demonstrated by infectivity assay, viral particles were detected by electron microscopy.

Animals↗
PubMed1986

Supertypic HLA-Bw4 antigen detected by a new monoclonal antibody.

A monoclonal antibody, HLAO1, was prepared by immunizing BALB/c mice with human lymphocytes of known HLA genotype. The monoclonal antibody is cytotoxic, of the IgG 2b isotype and binds to a protein of Mr 43,000 noncovalently associated with the beta 2-microglobulin. Genetic analysis proved complete concordance in the expression of the antigenic determinant defined by this monoclonal antibody and the presence of a supertypic (public) antigen, the HLA-Bw4. As expected, the monoclonal antibody also reacted with the antigens of HLA-A locus, A23, A24, and A32. The computer analysis of HLAO1 antibody binding to the Bw4/Bw6 heterozygous lymphocytes gave the approximate number of antigenic determinants, n = 2.2 X 10(4)/cell, and Ka = (5.9 +/- 0.8) X 10(9) M-1. Besides its potential immunochemical applications, the HLAO1 monoclonal antibody can become a useful tool in routine cytotoxicity typing of HLA antigens on peripheral lymphocytes.

Animals↗
PubMed1985

Replication of tick-borne encephalitis (TBE) virus in ticks Dermacentor marginatus.

In the laboratory experiments, the virophoric period in D. marginatus ticks lasted 61 to 81 d, the premoulting period (nymphs - adults) amounted to 17 to 18 d. The titres of individually examined females and males for the presence of TBE virus ranged from 10(1) to 10(5.5) ic mouse LD50/0.03 ml between the 14th and 29th day after hatching. In the laboratory experiments 77% of ticks were positive. In the field experiments, the virophoric period in D. marginatus ticks lasted 79 to 114 d, the premoulting period amounted to 34 to 38 d. The titres of individually examined adults for the presence of virus ranged from 10(1) to 10(5.5) ic mouse LD50/0.03 ml between the 13th and 80th day after hatching. In the field experiments 96.5% of ticks were positive.

Animals↗
PubMed1985

Replication of tick-borne encephalitis (TBE) virus in Ixodes ricinus ticks.

The influence of external factors on virus carriage of Ixodes ricinus ticks in laboratory and in nature was studied. In laboratory experiment, only one nymph was positive for the presence of virus on 120th day after metamorphosis. The virus titer was 10(2) mouse i.c. LD50/0.03 ml. Transmission experiments were negative. The nymphs were positive on 75th, 111th and 159th day after metamorphosis, always chilling in the field experiment. The titres of virus varied from the lowest detectable amount value to 10(3.6) mouse i.c. LD50/0.03 ml. The transmission of virus was positive in two cases.

Animals↗
PubMed1984

Establishment of a pluripotent embryonal carcinoma cell line not expressing SSEA-1 and ECMA-7 phenotypes.

A murine embryonal carcinoma (EC) cell line heterozygous for t0 recessive lethal mutation has been established from an embryo-derived transplantable teratocarcinoma TC1Ph of the genotype (129-T/t0 X C3H/Di)t0/+. The EC cell line, designated EC1Ph, and two cloned sublines, EC1Ph/a and EC1Ph/b, maintain the diploid karyotype (40, XY) and give rise to teratocarcinomas with differentiated derivatives of EC cells after inoculation into syngeneic recipients. The cloned sublines express low or zero amounts of SSEA-1 and ECMA-7 stage-specific antigens. At some passages, the EC1Ph line and the cloned subline EC1Ph/b express a significant quantity of class I H-2 antigens. This unusual EC phenotype resembles that of human teratocarcinoma cell lines.

Animals↗
PubMed1984

Gene expression of differentiated parent in teratocarcinoma cell hybrids. Repression or reprogramming?

The hybrid cell line H422 was constructed by fusing embryonal carcinoma (EC) cells of the PCC4AzaRCapR cell line with lymphocytes from a 129-tw32 mouse inbred strain female. An apparently complete extinction of stage-specific gene products of the lymphocyte parent was inferred from comparison of protein maps in two-dimensional PAGE of parental and hybrid cells, and from the reactivity patterns of monoclonal antibodies in radioimmunobinding assays. Furthermore, the hybrid cells display a true EC phenotype and EC functions, tumorigenicity and pluripotency. Taken together, the available evidence suggests either that the lymphocyte genome is a 'silent passenger' as far as the differentiated functions of hybrid cells are concerned, or that the developmentally restricted lymphocyte genome is reprogrammed in the hybrid cells back to a non-determined stage and both genomes thus act in a concerted manner.

Animals↗