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Biomedical subjects

I I Fodor

Publications and source records attributed to I I Fodor.

At least 19 recordsLinked to original sources
PubMed1992

[Expression of HIV-1 tat gene under the control of P 7,5 KD vaccinia virus promoter in CV-1 cells].

The transient expression of the HIV-1 gag genes and a HIV-1 ++trans-activator protein (tat)-encoded was made in cultured CV-1 cells. In recombinant plasmids, the gag gene was under the control of HIV-1 ++trans-activator sequence (tar) and the tat gene was under the control of a 7.5-kd vaccinia promoter. Transactivation of gag gene expression, which was stimulated by a tat gene expression product, was observed in the presence of wild vaccinia virus. The transaction was immunologically evaluated from the binding to monoclonal anti-p17 and anti-p24 antibodies. The findings lead to the discussion whether the regulatory proteins of HIV-1 can express in vaccinia virus vectors.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Authentic reverse transcriptase is coded by jockey, a mobile Drosophila element related to mammalian LINEs.

The mobile element jockey is similar in structural organization and coding potential to the LINEs of various organisms. It is transcribed at different stages of Drosophila ontogenesis. The Drosophila LINE family includes active transposable elements. Current models for the mechanism of transposition involve reverse transcription of an RNA intermediate and utilization of element-encoded proteins. As demonstrated here, a 2.23 kb DNA fragment from the region of jockey encoding the putative reverse transcriptase was stably introduced into an expression system under inducible control of the Escherichia coli lac regulatory elements. We describe the expression of the 92 kDa protein and identify this polypeptide alone as the authentic jockey reverse transcriptase based on some of its physical and enzymic properties. The jockey polymerase demonstrates RNA and DNA-directed DNA polymerase activities but lacks detectable RNase H, has a temperature optimum at 26 degrees C, requires Mg2+ or Mn2+ as a cofactor and is inactivated by sulphydryl reagent. The enzyme prefers poly(rC) and poly(rA) as template and 'activated' DNA is not effective.

Animals↗
PubMed1991

[Polymerase and immunologic activity of reverse transcriptase of the HIV-1 virus, isolated from Escherichia coli].

The recombinant reverse transcriptase of HIV-1 virus has been isolated from Escherichia coli cells transformed by the plasmid pRT40 DNA. The 103 Kd protein produced by these cells is shown to be processed to proteins with lower molecular masses by the reverse transcriptases own protease activity as well as Escherichia coli proteases. The resulting 103-66 Kd proteins possess the polymerase activity while 51 Kd and smaller proteins are lacking the activity. The 66 and 51 Kd reverse transcriptase fragments demonstrate the positive immunological reaction with the human blood serum from the people possessing antibodies to HIV-1 virus. The recombinant reverse transcriptase of HIV-1 produced by Escherichia coli cells is shown to be useful in AIDS diagnosis in humans.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Recombinant reverse transcriptase of Rous sarcoma virus: characterization of DNA polymerase and RNAase H activities.

Enzyme preparations of Rous sarcoma virus (RSV) reverse transcriptase have been isolated from a culture of E. coli HB101(pMF14). The enzyme has been purified to homogeneity and been shown to consist of two subunits, of molecular mass 97.4 and 61.3 kDa, respectively. The optimum conditions for the DNA polymerase and RNAase H activities, fidelity of DNA synthesis on a homogeneous RNA template, and the inhibitory effect of azidothymidine triphosphate have been determined. Data on the use of RSV recombinant reverse transcriptase for cDNA synthesis are given.

Avian Sarcoma Viruses↗
PubMed1991

[Expression of the glow worm luciferase gene in mammalian cells using vectors based on vaccinia viruses].

The transient expression of the two reporter genes, the genes for luciferase and bacterial beta-galactosidase, were used for comparative estimation of vaccinia viral promoters and for characterizing of the constructed plasmids. The recombinant clones of vaccinia virus expressing simultaneously and with high efficiency the luciferase and beta-galactosidase were used for studying the reproduction of vaccinia virus in mammalian cells. The advantages of the luciferase gene in using it as a reporter gene are discussed.

Animals↗
PubMed1989

[Features of integration of recombinant cosmids, containing Aspergillus terreus DNA, in the Saccharomyces cerevisiae genome].

A genome clonotheque of 25-40 kb Sau3A fragments of Aspergillus terreus DNA was constructed in the episomal cosmid vector pES33 containing the ARG4 gene of yeast. 23 independently originated stable Arg+ transformants were selected after transformation of the cir0 yeast strain ESH-O with pooled cosmid molecules. Both genetic and Southern analysis showed that 39% of these stable transformants occurred due to recombination between DNA sequences from A. terreus and Saccharomyces cerevisiae chromosome XII which took place most likely in the regions of homology within the ribosomal clusters. The data present the first evidence of in vivo recombination between foreign sequences and their S. cerevisiae counterparts.

Aspergillus↗
PubMed1988

Transformation of methylotrophic yeast Hansenula polymorpha: cloning and expression of genes.

We developed a host-vector system for transformation and gene cloning experiments using the methylotrophic yeast Hansenula polymorpha. Regeneration of protoplasts in a medium containing polyethylene glycol before plating made transformation more efficient and reproducible (2 to 3 x 10(4) micrograms DNA). The frequency of transformation was significantly lower when dominant resistance marker Cup1r was used for transformant selection. The transformation system developed was used to clone the DNA fragment which complements functionally the defect in the dihydroxyacetone kinase (DHAK*) activity of a H. polymorpha mutant strain. The DNA insert isolated was shown to increase by up to ten times the activity of DHAK in transformants carrying recombinant plasmids. When recombinant plasmids were introduced into S. cerevisiae, the transformants obtained acquired the ability to grow on the medium with dihydroxyacetone as a sole carbon source and the activity of DHAK was observed.

Cloning, Molecular↗
PubMed1988

Cosmids carrying Aspergillus terreus DNA can integrate into Saccharomyces cerevisiae chromosome XII via recombination between yeast and foreign DNAs.

A genome clonotheque consisting of 25- to 40-kb Sau3AI fragments of Aspergillus terreus DNA was constructed in the episomal cosmid vector pES33 containing the yeast ARG4 gene. From the 475 transformants of cir0 yeast strain ESH-0, 23 stable Arg+ transformants were independently selected. Genetic and Southern analysis of these stable transformants showed that 39% arose as a result of recombination between cloned A. terreus DNA sequences and yeast chromosome XII. The recombination events most likely occurred in the regions of homology within the rDNA clusters of A. terreus and Saccharomyces cerevisiae.

Aspergillus↗
PubMed1981

[Instability of hybrid plasmids containing Drosophila melanogaster DNA in rec+ and rec- Escherichia coli K-12 strains].

The stability of hybrid plasmids, constructed on the basis of vector pCV20(AprTcr) and containing HindIII fragments of Drosophila melanogaster DNA (pDm6, pDm9) and PstI fragments of D. melanogaster DNA (pDm39, pDm187, pDm189) was studied. After the transformation of E. coli HB101 recA and Escherichia coli 802 rec+ and selection to Tcr (pDm6, pDm9), or to Apr (pDm39, pDm189, pDm187) 0.04--9% of clones with reduced resistance to Tc or Ap was detected. The hybrid plasmids are more stable in rec-, but not in rec+ strain, the stability depends of the nature of cloned DNA, and on the site of vector DNA in which foreign genes are cloned. Restriction endonuclease analysis revealed that all plasmids of the clones with reduced Tcr or Apr lost the inserted DNA and the excision of foreign DNA occurred precisely in the sites of cloning. We suggest that the genome of the hybrid plasmid in the region of foreign insertion has a conformation which allows the bringing together the ends of cloned DNA with the following excision of the foreign genes.

Animals↗