Biomedical subjects

J Horst

Publications and source records attributed to J Horst.

At least 163 records · Page 9Linked to original sources

PubMed1982

Integration and expression of a truncated simian virus 40 early gene fragment in mammalian cells.

The recombinant plasmid p102 based on pBR322 carrying approximately equal to 50% of the replicator proximal early region of simian virus 40 (SV40) DNA, including the viral origin of replication, has been constructed. It lacks a major part of the large tumor (T) antigen 3'-coding region, the T-antigen termination codon, and the polyadenylylation site. The plasmid was transferred together with the herpes simplex virus thymidine kinase (TK) gene as a selectable marker to mouse LTK- cells. TK+ cell clones were isolated and their high molecular weight DNAs were shown by DNA blotting and hybridization experiments to contain the SV40 DNA fragment from the recombinant. In some of these clones, heterogeneous expression of the SV40 DNA fragment could be detected by immunofluorescence while, in control experiments in which a plasmid containing the complete SV40 early DNA region was used, this extensive heterogeneity of T-antigen expression was not observed. RNA . DNA hybridization experiments showed that the SV40-specific RNA of those clones is polyadenylylated. The molecular weight of the T-antigen-related protein coded by p102 corresponded well to the expected coding capacity of the SV40 DNA fragment. Small tumor antigen was not expressed.

Animals↗

PubMed1982

Production of a T-antigen-related protein in mammalian cells after stable transformation with a cloned SV40 gene fragment.

A recombinant plasmid based on pBR322 has been constructed which carries the replicator proximal early region of SV40 DNA, including the viral origin of replication (ORI). It lacks a major part of the tumour antigen 3'-coding region, the large T-antigen termination codon and the polyadenylation site. The recombinant plasmid was transferred together with the herpes simplex virus thymidine kinase gene, as a selectable marker into mouse LTK- cells. Integration and expression of the cloned SV40 gene fragment in TK+ transformants could be demonstrated by DNA restriction and blot hybridization and by immunofluorescence techniques.

Animals↗

PubMed1981

Heptacarpo-octatarso-dactyly combined with multiple malformation.

A case of heptacarpo-octatarso-dactyly combined with cheilo-gnatho-palato-schisis, hypertelorism, macroglossia, complex malformations of heart and great vessels, horse-shoe-kidney, micro-penis, and penis palmatus is described. To our knowledge, this syndrome has not yet been described in the literature. Some of the features of the case reported overlap with syndromes such as Grauhan syndrome and Meckel syndrome.

Abnormalities, Multiple↗

PubMed1981

[Biochemical evidence for integration of prokaryotic DNA into mammalian cells (author's transl)].

Experiments were undertaken to test for the stable integration of defined prokaryotic genes in mammalian cells. Thus lambda dvgal 88 plasmid DNA were transferred together with the herpes simplex virus type 1 thymidine kinase (TK) gene as a selectable marker to TK- mouse cells. DNA restriction and hybridization analysis of TK+ mouse cell clone DNA revealed (i) the presence of prokaryotic lambda dvgal 88 sequences in the mouse DNA; (ii) the stable integration of the prokaryotic DNA in mouse cell DNA under selective conditions; and (iii) the presence of lambda dvgal fragments in several copies per cell and their integration at different loci within the cell DNA.

Animals↗

PubMed1980

On procaryotic gene expression in eucaryotic systems.

Numerous types of interaction between pro- and eucaryotes exist in nature, from the endosymbiosis of some bacteria with unicellular organisms and insects to the complex systems of bacterial flora associated with the skin and intestines of animals and man, and nitrogen-fixation and crown-gall tumor induction in plants. Until recently, such interactions were not thought to include genetic transfer, but an increasing body of evidence points to the probability of similar naturally-occurring exchanges with wide-ranging implications for evolution and genetic manipulation. Experiments to elucidate the possible effects of procaryotic genes in eucaryotic systems have included in vitro and in vivo studies with both plant and animal systems, for instance the translation of bacterial messenger RNAs in the wheat germ and rabbit reticulocyte systems and the introduction of bacterial genes into plant protoplasts, animal cells and whole organisms. In the present paper we have tried to summarize the results of experiments involving the uptake, replication, transcription, translation and integration of procaryotic genes in various eucaryotic systems and to discuss the implications of such findings for basic research as well as for possible biomedical applications. Awareness of the possibility of procaryotic-eucaryotic genetic interactions may help to elucidate unresolved questions in pathology, such as possible involvement of the intestinal flora in carcinogenesis, as well as to provide valuable probes of eucaryotic control mechanisms and new approaches in agricultural genetic engineering.

Animals↗

PubMed1979

Variability of bacterial gene-directed enzyme production in human genetically deficient cells.

Human beta-galactosidase-deficient skin fibroblasts from a patient with generalized gangliosidosis (GMI-gangliosidosis type I) were treated with phage lambda plac DNA, coding for Escherichia coli beta-galactosidase (beta-D-galactoside galactohydrolase, EC.3.2.1.23). New beta-galactosidase activity detected in cell extracts of phage DNA-treated GMI-gangliosidosis fibroblasts continued to vary considerably from one experiment to another. It behaved like the E. coli z-gene product upon immunochemical and physicochemical investigation. In some experiments the antigenic behavior of resultant beta-galactoside activity in lambda plac DNA-treated cells resembled that of mutant E. coli beta-galactosidase. Among the factors and variables that may be responsible for the variation in the results obtained here and elsewhere, low physical binding between prokaryotic mRNA sequences and fibroblast ribosomal RNA could play a part connected with effective translation. This hypothesis is discussed under the aspect of a comparison of the ribosomal binding site of lac z mRNA with the 3'-terminus of the eukaryotic 18s ribosomal RNA, which shows limited possibilities for base-pairing interactions. More extensive possibilities for forming Watson-Crick base pairs between their initiation site and the eukaryotic ribosomal binding site exist for other prokaryotic messengers, such as those of Q beta-replicase, f 1-coat protein, or UDPG-4-epimerase.

Cells, Cultured↗

PubMed1979

[Salmonella freiburg: a new salmonella-serotype (3,10:1,Z13:1,2) (author's transl)].

A new Salmonella serotype (S. 3,10:1,Z13:1,2) was isolated from a stool specimen of a 13 year old immigrant from Narpan, USSR. The strain was finally identified as a new Salmonella, Subgenus I, on August 10, 1975 by Prof. Le Minor, International Salmonella Centre, Paris. The organism was introduced into the Kauffmann-White-Scheme, Supplement XX, as S. freiburg.

Adolescent↗

PubMed1975

Gene transfer to human cells: transducing phage lambda plac gene expression in GMI-gangliosidosis fibroblasts.

Genetic information from the bacterium Escherichia coli was transferred to human cells by means of the specialized transducing phage lambda plac carrying the bacterial z gene for the enzyme beta-galactosidase (geta-D-galactoside galactohydrolase, EC 3.2.1.23). As recipient cells, cultured skin fibroblasts from a patient with generalized gangliosidosis (GMI-gangliosidosis Type I) characterized by a severe deficiency of beta-galactosidase activity were used. The deficient human cells were incubated with the bacteriophage lambda plac or lambda plac DNA and beta-galactosidase activity was measured in order to detect gene transfer and acceptance of the prokaryotic information in the mammalian system for transcription and translation. The expression of the phage genome in the deficient fibroblasts could be demonstrated by detection of higher beta-galactosidase activity after incubation with phage lambda plac in three out of 19 experiments and in four out of 16 experiments after treatment with lambda plac DNA. Lambda plac DNA induced much higher enzyme activities than infective phage particles. Immunochemical and physicochemical assays could not distinguish the induced beta-galactosidase activity from that of the z-gene product of E. coli.

Cell Line↗

PubMed1973

Avian tumor virus RNA: a comparison of three sarcoma viruses and their transformation-defective derivatives by oligonucleotide fingerprinting and DNA-RNA hybridization.

Earlier electrophoretic analyses have shown that the 60-70S RNA of avian sarcoma viruses contains a characteristic subunit, termed class a subunit, which has a lower electrophoretic mobility than class b subunit found in transformation-defective derivatives of sarcoma viruses and in avian leukosis viruses. We have compared the RNAs of three nondefective avian sarcoma viruses, B77 and Prague and Schmidt-Ruppin strains of Rous sarcoma virus, with those of their transformation-defective (td) derivatives, td B77, td PR-C, and td SR-A, respectively, to determine the chemical basis for the difference between class a and b subunits. It was found by "fingerprinting" that (1) all (about 20-25) large T1 RNase-resistant oligonucleotides present in class b subunits of transformation-defective viruses have homologous counterparts in the class a subunits of corresponding nondefective sarcoma viruses and that (2) class a subunits contain a few (one or two) additional oligonucleotides that are not present in class b. By contrast the oligonucleotide fingerprints of avian tumor viruses of different strains and subgroups were very different.Cross hybridization of classes a and b RNA of sarcoma virus B77 with DNA transcribed from a corresponding transformation-defective virus td B77 showed that the two RNAs share at least 60% and differ by about 10% of their sequences. It is suggested that the structural relationship of class a and b subunits of corresponding viruses may be expressed as a = b + x, and that all the oligonucleotides present only in RNAs of sarcoma viruses but not in transformation-defective viruses of the corresponding strains are part of sequence(s) x. The possibility that x represents genetic information directly or indirectly involved in transformation of fibroblasts is discussed.

Alpharetrovirus↗

PubMed1972