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Biomedical subjects

T T Puck

Publications and source records attributed to T T Puck.

At least 91 records · Page 5Linked to original sources
PubMed1974

Genetics of somatic mammalian cells: biochemical genetics of Chinese hamster cell mutants with deviant purine metabolism.

Studies are presented on the biochemical genetics of 30 adenine-requiring mutants of the Chinese hamster ovary cell which were induced by mutagenesis and selected by the BrdU-visible light technique. Representative experiments conducted with these mutants include: hybridization with each other; hybridization with normal human cells; nutritional analysis; biochemical analysis with radioactively labeled intermediates; and measurement of reversion frequencies to wild-type phenotype occurring spontaneously and under the influence of selected mutagens. All mutants behave as if having point mutations. These experiments provide information relevant to the determination of dominant-recessive relationships, resolution into different complementation classes, localization of the human chromosomes which carry human genes required by the individual mutants, determination of the point of metabolic block for different mutants, and elucidation of the nature of the underlying DNA changes. These experiments illustrate the range of biochemical-genetic studies now possible with such a family of somatic mammalian cell mutants in vitro. Possible application to problems of human genetic disease are indicated.

Adenine↗
PubMed1973

Surface antigens of mammalian cells as genetic markers. II.

A second surface antigen, B(L), lethal in the presence of specific antibody and complement has been identified on some human cells and shown to behave as a good genetic marker. It is autosomal, unlinked to the human A(L) antigen previously described, and unlinked to 15 other human genes. The A(L) antigen, which is linked to the lactic dehydrogenase A gene, is found on the HeLa, the cultured human fibroblast, and in small amounts on the human lymphocyte. B(L) occurs on HeLa cells, on cultured human fibroblasts, and on human lymphocytes, but not on human RBCs. Hybrid cells formed by fusion of human and Chinese hamster cells have been prepared containing each of the four possible combinations of these two markers. Highly selective antisera sensitive to each marker separately can be obtained. The use of single-cell plating to demonstrate the presence of the antigens and of hybrid cells containing desired combinations of the markers facilitates study in this system.

Adsorption↗
PubMed1973

Detection of inborn errors of metabolism: galactosemia.

Radioautography of cultured, human, galactosemic and nongalactosemic cells shows that, in the presence of 0.05M D-galactono-gamma-lactone, the former incorporate much less galactose in acid-insoluble form than the latter. Presumably the lactone inhibits incorporation of the labeled galactose into pathways which do not require galactose-1-phosphate uridylyltransferase activity. Definite differences between the galactosemic and nongalactosemic condition can be demonstrated with as few as 100 to 1000 cells. This approach may be useful in facilitating prenatal detection of several kinds of inborn errors of metabolism.

Amino Acid Metabolism, Inborn Errors↗
PubMed1972

Genetics of somatic mammalian cells: demonstration of a human esterase activator gene linked to the adeB gene.

Prototrophic hybrids formed from an adenine-requiring Chinese hamster cell and human fibroblasts uniformly display new esterase activity that differs from that of either parental cell in electrophoretic mobility and substrate specificity. The hybrids that grew in the selective medium and possessed the new esterase activity had a single extra chromosome that resembled a B-group human chromosome. When clones of such hybrid cells were cultured in nonselective medium, they rapidly reverted to inability to synthesize adenine, disappearance of the new esterase activity, and simultaneous loss of the extra human chromosome. Esterase activity like that of the hybrid is present in cells of various Chinese hamster, but not human, tissues. It is postulated that particular Chinese hamster esterase genes became inactive after longterm cultivation, and that, in the hybrid cell, a human activator gene linked to the adeB gene and located on a human B-group chromosome reactivated expression of these Chinese hamster esterase genes.

Adenine↗
PubMed1972

Membrane dynamics in the action of dibutyryl adenosine 3':5'-cyclic monophosphate and testosterone on mammalian cells.

The first manifestation of reverse transformation, in which a permanent epithelial-like cell is reversibly transformed into a fibroblast-like cell by dibutyryl adenosine cyclic 3':5'-monophosphate, is the disappearance of a set of violently extending and retracting knobbed structures on the cell membrane with consequent tranquilization of the membrane. The cell then elongates to assume a fibroblast-like morphology. Permanently fibroblast-like cells, which have smooth membranes, can be changed into knobbed epithelial-like cells by the addition of either colcemid or cytochalasin B, agents that disorganize one or the other component, respectively, of the microtubular-microfibrillar system. Permanently smoothmembraned, epithelial-like cells also become knobbed by such treatment. All of these knobbed epithelial-like cells can be converted into smooth-membraned fibroblast-like cells by dibutyryl cAMP alone or with the aid of supporting molecules like testosterone. It is proposed that these are general phenomena and that the knobbed epithelial-like forms and the more highly differentiated smooth-membraned fibroblast-like cells represent extreme situations with respect to the degree of organization of the microtubular-microfibrillar system inside the cell.

Animals↗
PubMed1971

Genetics of somatic mammalian cells: lethal antigens as genetic markers for study of human linkage groups.

The antigen that causes killing of at least 98% of a human cell population treated with a 1% solution of a specific rabbit antiserum in the presence of complement is a sensitive genetic marker. The rapid loss of human chromosomes in human-Chinese hamster cell hybrids makes possible a convenient test of linkage relationships with this marker. Hybrid clones with and without the lethal antigen were isolated and analyzed. In 76 clones and subclones studied, 41 carried both the lethal antigen and the lactic dehydrogenase-A marker, 35 carried neither, and no clones contained only one of the two markers. In contrast to this clear demonstration of linkage, absence of linkage was found between the lethal antigen and the following markers: Lactic dehydrogenase B, NAD-dependent malic dehydrogenase, NADP-dependent malic dehydrogenase, glucose-6-phosphate dehydrogenase, phosphoglucomutase, glutamate oxaloacetate transaminase, indophenol oxidase, glucose phosphate isomerase, proline, inositol, hypoxanthine B, and glycine A. This lethal antigen appears to be carried on a single human autosome.

Animals↗
PubMed1971

Morphological transformation of Chinese hamster cells by dibutyryl adenosine cyclic 3':5'-monophosphate and testosterone.

Treatment of Chinese hamster ovary cells in vitro with dibutyrl adenosine cyclic 3':5'-monophosphate converts the culture from one of compact, randomly oriented cells that grow in multilayers to a monolayer of elongated, fibroblast-like cells growing parallel to one another. Testosterone propionate, which has a similar though smaller effect at high concentrations and after prolonged incubation, potentiates the action of dibutyryl cyclic AMP even when added at very low concentrations. The transformation is recognizable within one hour, affects cells throughout all or most of the life cycle, and is completely reversible. Both cell forms can reproduce, with approximately the same generation time. Agents like colcemid and vinblastine, which inhibit assembly of microtubules, prevent the transformation to the fibroblast-like form. It is postulated that the dibutyryl cyclic AMP and testosterone act by promoting organization of microtubules from protein monomers.

Adenine Nucleotides↗
PubMed1971

Further changes in differentiation state accompanying the conversion of Chinese hamster cells of fibroblastic form by dibutyryl adenosine cyclic 3':5'-monophosphate and hormones.

The morphological conversion in vitro of Chinese hamster ovary cells to a fibroblast form by a relatively large amount of dibutyryl adenosine cyclic 3':5'-monophosphate, or by a combination of small amounts of this compound and testosterone, is attended by appearance of the following additional properties: acquisition of strict contact inhibition of growth; reorientation of the random growth pattern into one in which cells grow parallel to their long dimension; disappearance of the randomly distributed, knob-like, pseudopodal structures around the cell periphery; induction of collagen synthesis; and decrease in the ability to be agglutinated and rounded up by plant agglutinins and specific cell antibodies. The changes in these characteristics are consistent with the conversion from a malignant to a normal fibroblastic state. This conversion is under genetic control, as demonstrated by the production of specific mutants with altered characteristics. The response to testosterone is specific since steroids like estradiol and hydrocortisone are inactive, and others have limited activity. Some prostaglandins are equal in activity to testosterone and 5alpha-dihydrotestosterone. This system appears useful in study of the regulation of phenotypic expression in mammalian cells.

17-Ketosteroids↗
PubMed1969

Complementation analysis on virus-fused Chinese hamster cells with nutritional markers.

Cell fusion experiments have been carried out with Chinese hamster cell mutants with different nutritional growth requirements. Conditions have been devised in which approximately 1 to 2 percent of the cell population remaining after fusion are fused, hybrid cells. The all-or-none nature of the genetic markers employed and the extremely low reversion rates insure that no contamination of the hybrid population with parental forms occurs. Hybrids between glycine- and hypoxanthine-requiring mutants are prototrophic, which indicates that both mutations are recessive. Hybrids between a glycine-deficient mutant and a singlestep mutant which requires glycine, hypoxanthine, and thymidine are relieved of the glycine dependency, an indication that the two loci associated with glycine dependence are different. This mutation to the triple-supplement requirement as well as a proline deficiency were also shown to be recessive mutations. The system appears applicable to a variety of genetic problems.

Animals↗