scholarly journals GENETICS OF SOMATIC MAMMALIAN CELLS. IV. PROPERTIES OF CHINESE HAMSTER CELL MUTANTS WITH RESPECT TO THE REQUIREMENT FOR PROLINE

Genetics ◽  
1967 ◽  
Vol 55 (3) ◽  
pp. 513-524 ◽  
Author(s):  
Fa-Ten Kao ◽  
Theodore T Puck
Keyword(s):  
Mammalian Cells ◽  
Chinese Hamster ◽  
Chinese Hamster Cell

scholarly journals DERIVATION OF TK- CLONES FROM REVERTANT TK+ MAMMALIAN CELLS

Genetics ◽  
1973 ◽  
Vol 75 (3) ◽  
pp. 515-530
Author(s):  
D J Roufa ◽  
B N Sadow ◽  
C T Caskey
Keyword(s):  
Cell Lines ◽  
Mammalian Cells ◽  
Chinese Hamster ◽  
Chinese Hamster Cell ◽  
Single Step ◽  
Wild Type ◽  
Cell Clones ◽  
Selection Experiments ◽  
Step Selection ◽  
Selection Of

ABSTRACT In order to obtain a large collection of Chinese hamster cell clones defective in thymidine kinase (TK-), BrdUr selection experiments have been performed on wild-type and revertant TK+ cell lines. No clones (< 10-9) were obtained from the wild-type TK+ cell line by single-step selection. In contrast, revertant TK+ clones readily gave rise to stable TK- derivatives (1 - 2 × 10-4). Both wild-type and revertant TK+ clones spontaneously yielded 8-AGr colonies with the same frequency (1 - 5 × 10-6), suggesting that the differences between wild-type and revertant cell lines specifically affected selection of the TK- phenotype. The increased frequency of TK- clones reflects perhaps the number (ploidy) or character of the autosomal TK loci in TK+ revertants, or perhaps the mechanisms which regulate expression of the TK genes. Several mutagens, EMS, MNNG and UV, stimulated the TK+ revertants' frequency of TK- subclones only slightly (< 3-fold). Biochemical and genetic data indicated that the TK- clones derived from one revertant are phenotypically different. The phenotypes displayed by these cell lines are stable and do not depend upon the continued presence of the selective agent.

scholarly journals Defective Brca2 influences topoisomerase I activity in mammalian cells.

2003 ◽  
Vol 50 (1) ◽  
pp. 139-144 ◽  
Author(s):  
Iwonna Rahden-Staroń ◽  
Maria Szumiło ◽  
Emilia Grosicka ◽  
Maria Kraakman van der Zwet ◽  
Małgorzata Z Zdzienicka
Keyword(s):  
Mammalian Cells ◽  
Topoisomerase I ◽  
Chinese Hamster ◽  
Brca2 Gene ◽  
Nuclear Extract ◽  
Chinese Hamster Cell ◽  
V79 Cells ◽  
Cell Mutant ◽  
Relaxation Activity ◽  
Nuclear Extracts

The Chinese hamster cell mutant V-C8 is defective in the Brca2 gene (Kraakman-van der Zwet et al., 2002, Cell Biol.; 22: 669). Here we report that V-C8 cells were 10-fold more sensitive to camptothecin, an inhibitor of topoisomerase I, than the parental V79 cells. The level of the relaxation activity of topoisomerase I in nuclear extracts was also lower (4-fold) in V-C8 than V79 cells, in spite of the fact that the level of the topoisomerase I protein was the same in these cells. The survival of V-C8 cells in the presence of camptothecin, the sensitivity of V-C8 topoisomerase I to camptothecin, and the level of the relaxation activity in V-C8 nuclear extract were almost completely restored by transfection of V-C8 cells with the murine Brca2 gene or by the transfer of human chromosome 13 providing the BRCA2 gene. These results indicate that the observed changes in the topoisomerase I activity in V-C8 are due to the defective function of the Brca2 gene.

Ultrastructural Changes in Three Different Mammalian Cells Following Ultraviolet Laser Irradiation

1972 ◽  
Vol 30 ◽  
pp. 350-351
Author(s):  
K. Shankar Narayan ◽  
Kailash C. Gupta ◽  
Tohru Okigaki
Keyword(s):  
Ultraviolet Light ◽  
Mammalian Cells ◽  
Biological Effects ◽  
Survival Rates ◽  
Chinese Hamster ◽  
Cell Types ◽  
Differential Sensitivity ◽  
Ultrastructural Changes ◽  
Ultraviolet Laser

The biological effects of short-wave ultraviolet light has generally been described in terms of changes in cell growth or survival rates and production of chromosomal aberrations. Ultrastructural changes following exposure of cells to ultraviolet light, particularly at 265 nm, have not been reported.We have developed a means of irradiating populations of cells grown in vitro to a monochromatic ultraviolet laser beam at a wavelength of 265 nm based on the method of Johnson. The cell types studies were: i) WI-38, a human diploid fibroblast; ii) CMP, a human adenocarcinoma cell line; and iii) Don C-II, a Chinese hamster fibroblast cell strain. The cells were exposed either in situ or in suspension to the ultraviolet laser (UVL) beam. Irradiated cell populations were studied either "immediately" or following growth for 1-8 days after irradiation.Differential sensitivity, as measured by survival rates were observed in the three cell types studied. Pattern of ultrastructural changes were also different in the three cell types.

2,4-Dichlorophenol and MCPA in a V79 Test

1988 ◽  
Vol 15 (3) ◽  
pp. 245-250
Author(s):  
Geirid Fiskesjö
Keyword(s):  
Chinese Hamster ◽  
Chinese Hamster Cell ◽  
Test System ◽  
Similar Degree ◽  
Human Beings ◽  
Industrial Chemicals ◽  
Allium Test ◽  
Chinese Hamster Cell Line ◽  
A Cell ◽  
Mutagenic Effects

Two industrial chemicals, 2,4-dichlorophenol and 4-chloro-2-methylphenoxyacetic acid (MCPA), which have no toxic effects on the Chinese hamster cell line V79 alone, were tested for toxicity and mutagenicity in a cell-mediated test, where mixed-function oxidase (MFO) enzymes are active in the metabolism of xenobiotics. For 2,4-dichlorophenol, a dose-dependent toxicity as well as a slight mutagenicity could be shown when oxygenation enzymes were present. A similar degree of toxicity in a plant test system (the Allium test) indicates a similar risk of damage from exposure to dichlorophenol treatments in both these systems. MCPA did not induce any toxic or mutagenic effects at the concentrations tested. These results were not in agreement with previous results in plant material, where MCPA was clearly toxic at relatively low doses. However, since chlorophenols have been found in plants sprayed with phenoxyacetic acids, further investigations should be performed concerning potential risk to human beings.

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