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Results for “hybridization”

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At least 37 records · Page 2Linked to original sources
PubMed1975

Somatic cell hybrids between mouse peritoneal macrophages and simian-virus-40-transformed human cells: II. Presence of human chromosome 7 carrying simin virus 40 genome in cells of tumors induced by hybrid cells.

Cells derived from tumors induced in "nude" mice after injection of cells that were hybrids between mouse peritoneal macrophages and simian virus 40 (SV40)-transformed human cells were found to retain the human chromosome 7 carrying the SV40 genome, and indicate that the presence of human chromosome 7 carrying the SV40 genome is responsible for the expression of the tumorigenic phenotype in the hybrid cells.

Animals↗
PubMed1978

F1-hybrid anti-parental-strain reactivity. II. Proliferation of C3H X CBA hybrid lymphocytes in the spleens of irradiated CBA mice.

Experiments were conducted to explore whether C3H X CBA lymphocytes can react by proliferation when they meet parental CBA spleen cells. MLC tests could not detect such a reaction, but infusion of C3H X CBA lymph node cells into irradiated CBA hosts resulted in rapid cell proliferation in the host's spleen. Such a cell proliferation was also observed after infusion of T-cell-enriched lymph node cell preparations or thymic cells from C3H X CBA donors. Upon transfer to new irradiated mice these proliferating cells continued to proliferate in CBA mice but not in C3H X CBA mice. Further evidence that the injected T-cells were the proliferating emerged from experiments where AKR X CBA lymphocytes were found to proliferate in spleens of irradiated CBA mice and that most of these cells posessed the theta antigen determined by AKR. Proliferation of F1-hybrid lymphocytes in the spleens of its irradiated parental strains was found not to be a general phenomenon and is probably restricted to some Mls-antigen-compatible strain combinations. The possibility that the C3H X CBA hybrid lymphocytes are stimulated to proliferations by CBA lymphocytes reactive against the C3H-determined Mls antigen is discussed.

Animals↗
PubMed1978

Construction of a novel plasmid-phage hybrid: use of the hybrid to demonstrate ColE1 DNA replication in vivo in the absence of a ColE1-specified protein.

A hybrid bacteriophage, P420, was constructed in vitro; it contains part of bacteriophage P4 and a 3.6-kilobase derivative of plasmid ColE1. In Escherichia coli, the plasmid-phage hybrid can exist as a stable plasmid or can be packaged into infective bacteriophage particles. Replication of P420, directed by the ColE1 replicon, was found to occur after P420 phage infection of E. coli cells that had been incubated in the presence of chloramphenicol. Replication began without a lag period and resulted in the synthesis of covalently closed circles of P420 DNA. Like ColE1 DNA replication but unlike that of P4, replication was dependent on DNA polymerase I and was sensitive to rifampicin. The presence of a resident ColE1 plasmid in the infected cells resulted in an inhibition of the replication of the incoming P420 DNA. These results indicate that ColE1 does not require a plasmid-coded protein to replicate its DNA in vivo and demonstrate the utility of P4 bacteriophage for coupling bacteriophage properties to a plasmid replicon.

Bacterial Proteins↗
PubMed1978

Expression of transformation in cell hybrids. II. Nonsuppression of the transformed phenotype in hybrids between a chemically transformed and nontransformed derivatives of Balb/3T3.

Hybrid clones derived from a nitrosocarbaryl-transformed Balb/3T3 cell line, Clone H, and a nontransformed cell line THO2 resemble the transformed parent in the clone morphology, higher saturation density, colony formation in medium with reduced serum concentration, growth in agarose and ability to form clones on Balb/3T3 monolayer. Results are discussed in the framework of genetic models which permit or require dominant mutations for the expression of transformed phenotype.

Animals↗
PubMed1979

Expermental hybridization within the genus Triturus (Urodela: Salamandridae). III. Evidence for crossing-over, true chiasmata and chomosomal homologies in the spermatogenesis of F1 species hybrids, T. cristatus carnifex female X T. marmoratus male.

Spermatogenesis in the F1 hybrid (2n=24=12 female + 12 male) between the closely related newt species T. cristatus carnifex and T. marmoratus was apparently normal up to pachytene. Many unpaired chromosomes were present at diplotene and a typical diakinesis was lacking. Primary spermatocytes at meta- and meta-anaphase contained up to 12 regular intergenomal bivalents and a corresponding number of univalents when less then 12 II. Most chiasmata were terminal or subterminal, some intercalary. Chiasmata between corresponding heterospecific chromosomes can be reported as true: real crossing over has taken place, proving the presence of primary chromosomal homologies between the 2 sets of the parental species. Evidence for recombination is based on the segregation of particular markers (i.e., subterminal C-bands and NORs) observed in certain chromosomes at metaphase II. One chromatid of single chromosomes can show the T. cristatus "pheno-type" and the other the T. marmoratus phenotype". A few primary spermatocytes contain a certain number of irregular associations (intragenomal or intrahaploid bivalents, irregular intergenomal bivalents, chromosome multivalents) joined by chiasmata which can be defined as anomalous. Other abnormalities concern the occurrence of interlocked bivalents which occasionally show an anomalous exchange between heterologous chromatids. Cytogenetic criteria useful to evaluate the taxonomic relationships between different species have been discussed as well as some possible trends in chromosome evolution and speciation within the genus Triturus.

Animals↗
PubMed1977

Expression of differentiated functions in hepatoma cell hybrids: selection in glucose-free media of segregated hybrid cells which reexpress gluconeogenic enzymes.

Selective glucose-free media have been used to study the reexpression of liver-specific gluconeogenic enzymes in rat hepatoma X mouse lymphoblastoma somatic hybrids. The utilization for gluconeogenesis of dihydroxyacetone or oxaloacetate requires two enzymes: fructose diphosphatase as well as either triokinase for the former or phosphoenolpyruvate carboxykinase for the latter. By sequential selection with these substrates, the reexpression of the three gluconeogenic enzymes has been dissociated. The reexpression of these enzymes is correlated with the loss of mouse chromosomes. In addition, the characterization of the parental forms of aldolase B, another liver-specific enzyme, shows that reexpression corresponds to the simultaneous production of the rat and mouse enzymes. These results demonstrate the chromosomal origin of extinction and suggest that activation of mouse silent genes which accompanies reexpression can occur without loss of the parental determinations. The hypothesis that determination involves regulatory rather than structural genes is discussed.

Alcohol Oxidoreductases↗
PubMed1976

[Somatic hybridization and oncogenesis: induction of tumors in mice by administration of mixtures of cells of the homologous organs and their hybrids].

The 2 months old C57BL/6J mice were injected with the mixtures of kidney and spleen cells from mice of the same strain or of the same cells following the hybridization induced by Sendai virus. The tumours of liver, kidney and lymphoid system appeared in 25% of recipients within 12--14 months. The result obtained is predicted by the general theory of oncogenesis proposed early by L. B. Mekler.

Animals↗