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Biomedical subjects

F T Kao

Publications and source records attributed to F T Kao.

At least 91 records · Page 5Linked to original sources
PubMed1980

Chromosomal assignment of the gene for folylpolyglutamate synthetase to human chromosome 9.

An auxotrophic mutant, GAT-, derived from the Chinese hamster cell line CHO-K1 and exhibiting multiple growth requirements for glycine, adenine, and thymidine, has been shown to be deficient in one of the folate-dependent enzymes, folylpolyglutamate synthetase (FPGS). This mutant was fused with normal human lymphocytes and human lymphoblasts and 41 GAT+ primary hybrid clones were isolated in medium lacking glycine, adenine, and thymidine. In addition, 71 secondary clones were isolated after growth of four primary hybrid clones in enriched medium, which allows losing the complementing human chromosome without losing cell viability. Analysis of human isozyme markers in the 112 primary and secondary clones established a syntenic relationship between the GAT marker and AK1, an isozyme marker for human chromosome 9. Enzyme studies of the parental and hybrid cells not only showed restored enzyme activities of FPGS in the hybrids, but also demonstrated that several enzyme characteristics of FPGS in the hybrids are consistent with those of the human enzyme. Thus, it is concluded that the human gene coding for the enzyme FPGS which complements the auxotrophic mutant GAT- in the CHO-K1 cells can be assigned to human chromosome 9. This assignment provides an additional selective marker for mammalian cell genetic analysis in which human chromosome 9 can be selectively and stably retained in the cell hybrids.

Animals↗
PubMed1979

Precise localization of human beta-globin gene complex on chromosome 11.

Cloned DNA probes were used in combination with a panel of five hybrid cell clones containing a series of different terminal deletions in human chromosome 11 to map precisely the human hemoglobin beta and delta chain structural genes contained on this chromosome. The region of deletion in each clone of the panel has been defined by biochemical, immunologic, and cytogenetic markers. DNA from clones containing successively larger terminal deletions was tested with appropriate DNA probes to determine the point on the chromosome at which DNA for these two closely linked hemoglobin genes is deleted. These genes, and by inference the closely linked G gamma and A gamma globin genes as well, have been assigned to the intraband region 11p1205 leads to 11p1208 on the short arm of chromosome 11, an interval containing approximately 4500 kilobases of DNA. The approach appears to have potential for even greater resolution and reasonably wide applicability for gene mapping.

Animals↗
PubMed1979

Regional assignment of human genes TPI1, GAPDH, LDHB, SHMT, and PEPB on chromosome 12.

Karyological analysis was performed on a series of human-Chinese hamster cell hybrids containing deletions of human chromosome 12. Chromosome breakage was produced by treatment of the cells with either X-rays or 5-bromodeoxyuridine and near-visible light. The hybrid clones were analyzed for the presence or absence of the following five human gene markers known to be located on chromosome 12: triosephosphate isomerase-1 (TPI1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), lactate dehydrogenase-B (LDHB), serine hydroxymethyltransferase (SHMT), and peptidase-B (PEPB). Based on the correlation between the isozyme markers and karyological analysis of these clones, a regional map of the five human genes on chromosome 12 was established. The linear order for these genes is: pter-TPI1-GAPDH-LDHB-centromere-SHMT-PEPB-qter. The locations of these genes are: TPI1, GAPDH, LDHB: pter leads to p12; SHMT: q12 leads to q14; PEPB: q14 leads to qter. Statistical analysis similar to that of Goss and Harris (1975, 1977a, b) has been performed on the segregation data in the hybrid clones. The statistical map, in general, agrees with the cytogenetic map and further localizes PEPB to 12q21.

Animals↗
PubMed1978

Regional mapping of the gene for human lysosomal acid phosphatase (ACP2) using a hybrid clone panel containing segments of human chromosome 11.

A clone panel containing various segments of human chromosome 11 has been selected and use for regional assignment of the gene for human lysosomal acid phosphatase (ACP2) to the short arm of chromosome 11, in the region 11p11 leads to 11p12. Further evidence has also been presented to update the regional assignment of the gene for lactate dehydrogenase A (LDHA) to 11p12 leads to 11p13, and to support a previous assignment of the genes for the two components of the human cell-surface antigens of the SA11 (previously designated AL) group, SA11-1 and SA11-3 (previously designated AL-a1 and AL-a3), to 11pter leads to 11p13. This regional clone panel will be useful for rapid regional mapping of other genes assigned to chromosome 11.

Acid Phosphatase↗
PubMed1978

Induced segregation of human syntenic genes by 5-bromodeozyuridine + near-visible light.

Chromosome-breaking agents have been used in two different procedures for promoting segregation of syntenic genes on human chromosome 12. In method A, a human-Chinese hamster cell hybrid containing the single human chromosome 12 was treated either with 5-bromodeoxyuridine BrdU + near-visible light or with X-rays. In method B, normal human fibroblasts were treated with BrdU + near-visible light followed by their fusion with a Chinese hamster glycine-requiring cell mutant CHO-K1/gly-A. Since the human complementing gene for serine hydroxymethyltransferase, an enzyme deficient in gly-A, lies on human chromosome 12, only those hybrids retaining that chromosome can survive the glycine-free medium. Clones isolated from both procedures were analyzed for the loss or retention of four other syntenic genes on chromosome 12, TPI, GAPD, LDH B, and PepB. The results demonstrate that method B is much more effective in generating clones with extensive marker losses. In addition, the segregation pattern and frequency obtained in this study provided information on the linear order of TPI and GAPD on chromosome 12.

Bromodeoxyuridine↗
PubMed1977

Genetics of cell-surface antigens: regional mapping of three components of the human cell-surface antigen complex, AL, on chromosome 11.

Cytogenetic analysis has been performed on a series of deletion mutations on human chromosome 11 of AL hybrid clones in which specific markers have been lost as a result of treatment with mutagenic agents. Such analysis has localized the three previously identified components of the AL cell-surface antigen complex to the indicated regions of chromosome 11: a1 and a3:11p13 leads to 11pter; a2:11q13 leads to 11qter. Using these methodologies human lactic dehydrogenase A localization on the short arm as reported by others has been confirmed. Evidence is presented provisionally assigning this gene to 11p13 leads to 11pter.

Antigens↗
PubMed1977

Synteny between glycinamide ribonucleotide synthetase and superoxide dismutase (soluble).

The auxotrophic mutant ade -C derived from Chinese hamster ovary cell CHO-K1 lacks the enzyme glycinamide ribonucleotide synthetase and requires exogenous supplement of purines for growth. Cells from this mutant were fused with normal human lymphocytes, and the resulting hybrids were isolated in purine-deficient medium. A total of 32 primary clones and 49 secondary clones were analyzed for various isozyme markers. Cytogenetic analysis with chromosome banding was also performed in some hybrid clones. The results provide evidence indicating that glycinamide ribonucleotide synthetase is syntenic with superoxide dismutase (soluble) and is located on human chromosome 21.

Animals↗
PubMed1976

Genetics of somatic mammalian cells: genetic, immunologic, and biochemical analysis with Chinese hamster cell hybrids containing selected human chromosomes.

Through hybridization of specific Chinese hamster cell auxotrophs with human cells and selection in media lacking the nutritional supplements required by the former cells, a series of stable hybrid clones can be prepared. These hybrids have genomes consisting of a common part--the complete or almost complete set of Chinese hamster chromosomes, plus a variable part--one or a few human chromosomes. The identity of the human chromosomes can be varied by utilizing different Chinese hamster auxotrophs and the appropriate selective media. The human chromosomes present can be determined by a combination of cytogenetic analysis with chromosome banding and testing for specific human marker genes. Hybrids containing single human chromosomes 11 and 12 and the combination of both 11 and 12 are described. The system appears to lend itself to various studies such as identification of human cell surface antigens, determination of their chromosomal loci, measurement of their distribution among cells of normal human tissues, study of interrelations among syntenic and asyntenic genes, and mutational analysis of the human genome.

Animals↗
PubMed1975

Lack of correlation between malignancy and sensitivity to killing by concanavalin A.

Eight mouse cell lines and seven hybrid clones, both malignant and nonmalignant, were tested for possible correlations between malignancy and sensitivity to killing by concanavalin A (Con A). These cells included six highly malignant and two less malignant cell lines, two malignant and three nonmalignant hybrid clones derived from five different crosses, and two malignant hybrid clones segregated from a cross between malignant and nonmalignant cells. The malignancy of the cells was determined by their ability to grow progressively in irradiated, syngeneic newborn mice and to kill the host. All these cells, except one, showed similar sensitivities to killing by Con A. No correlation could be established between the malignancy of a cell line or of a hybrid clone and its sensitivity to the lectin.

Animals↗
PubMed1975

Mutagenesis and genetic analysis with Chinese hamster auxotrophic cell markers.

Chinese hamster ovary cells were treated with various physical and chemical mutagens and subject to the bromodeoxyuridine plus visible light procedure for isolation of auxotrophic mutants. more than 200 auxotrophs have been isolated which require exogenous supplement of various nutrilites for growth, such as glycine, adenine, thymidine, inositol, etc. Fifty-five of these have been characterized by complementation tests and were shown to constitute 15 different loci. All these auxotrophs are highly stable and exhibit all-or-none growth response to the respective nutrilites. Enzyme deficiencies have been identified in several of these classes. When these auxotrophs are hybridized with human cells and grown in selective medium, the hybrids lose human chromosomes at a rapid rate and the analysis for synteny of the human genes can be successfully carried out. Moverover, in hybrids formed between an adenine-requiring auxotroph and human cells, a human esterase activator gene has been identified which appears to regulate the expression of esterase gene activities in the Chinese hamster genome. Studies of this kind may lead to the understanding of gene regulation in mammalian cells.

Animals↗
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

Identification of chick chromosomes in cell hybrids formed between chick erythrocytes and adenine-requiring mutants of Chinese hamster cells.

When chick erythrocytes were fused with adenine-requiring mutants of Chinese hamster cells of two different complementation classes and grown in adenine-free medium for 1 week or longer, mitotic cells were observed containing both chick and Chinese hamster metaphase chromosomes within a single cell. Stable hybrid clones were subsequently isolated that possessed, in addition to a complete Chinese hamster genome, a single specific chick chromosome. Hybrids resulting from fusions involving different adenine mutants retained different, identifiable chick chromosomes. Thus, the two chick genes for the endogenous synthesis of adenine were assigned to the respective chick chromosomes.

Adenine↗