Coordinate amplification of metallothionein I and II genes in cadmium-resistant Chinese hamster cells: implications for mechanisms regulating metallothionein gene expression

1985 ◽  
Vol 5 (2) ◽  
pp. 320-329
Author(s):  
B D Crawford ◽  
M D Enger ◽  
B B Griffith ◽  
J K Griffith ◽  
J L Hanners ◽  
...  
Keyword(s):  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Chinese Hamster ◽  
Chinese Hamster Cell ◽  
Chinese Hamster Cells ◽  
Future Studies ◽  
Noncoding Regions ◽  
Genes Encoding ◽  
Chinese Hamster Cell Line

We describe here the derivation, characterization, and use of clonal cadmium-resistant (Cdr) strains of the Chinese hamster cell line CHO which differ in their metallothionein (MT) induction capacity. By nondenaturing polyacrylamide gel electrophoresis, we showed that the stable Cdr phenotype is correlated with the augmented expression of both isometallothioneins (MTI and MTII). In cells resistant to concentrations of CdCl2 exceeding 20 microM, coordinate amplification of genes encoding both isometallothioneins was demonstrated by using cDNA MT-coding sequence probes and probes specific for 3'-noncoding regions of Chinese hamster MTI and MTII genes. Molecular and in situ hybridization analyses supported close linkage of Chinese hamster MTI and MTII genes, which we have mapped previously to Chinese hamster chromosome 3. This suggests the existence of a functionally related MT gene cluster in this species. Amplified Cdr variants expressing abundant MT and their corresponding Cds parental CHO cells should be useful for future studies directed toward elucidating the mechanisms that regulate expression of the isometallothioneins.

scholarly journals Coordinate amplification of metallothionein I and II genes in cadmium-resistant Chinese hamster cells: implications for mechanisms regulating metallothionein gene expression.

1985 ◽  
Vol 5 (2) ◽  
pp. 320-329 ◽  
Author(s):  
B D Crawford ◽  
M D Enger ◽  
B B Griffith ◽  
J K Griffith ◽  
J L Hanners ◽  
...  
Keyword(s):  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Chinese Hamster ◽  
Chinese Hamster Cell ◽  
Chinese Hamster Cells ◽  
Future Studies ◽  
Noncoding Regions ◽  
Genes Encoding ◽  
Chinese Hamster Cell Line

We describe here the derivation, characterization, and use of clonal cadmium-resistant (Cdr) strains of the Chinese hamster cell line CHO which differ in their metallothionein (MT) induction capacity. By nondenaturing polyacrylamide gel electrophoresis, we showed that the stable Cdr phenotype is correlated with the augmented expression of both isometallothioneins (MTI and MTII). In cells resistant to concentrations of CdCl2 exceeding 20 microM, coordinate amplification of genes encoding both isometallothioneins was demonstrated by using cDNA MT-coding sequence probes and probes specific for 3'-noncoding regions of Chinese hamster MTI and MTII genes. Molecular and in situ hybridization analyses supported close linkage of Chinese hamster MTI and MTII genes, which we have mapped previously to Chinese hamster chromosome 3. This suggests the existence of a functionally related MT gene cluster in this species. Amplified Cdr variants expressing abundant MT and their corresponding Cds parental CHO cells should be useful for future studies directed toward elucidating the mechanisms that regulate expression of the isometallothioneins.

scholarly journals THE EFFECT OF THYMIDINE ON THE DURATION OF G1 IN CHINESE HAMSTER CELLS

1967 ◽  
Vol 35 (1) ◽  
pp. 53-59 ◽  
Author(s):  
R. A. Tobey ◽  
E. C. Anderson ◽  
D. F. Petersen
Keyword(s):  
Cell Line ◽  
Generation Time ◽  
Culture Media ◽  
Chinese Hamster ◽  
Chinese Hamster Cell ◽  
Media Analysis ◽  
G1 Phase ◽  
Chinese Hamster Cells ◽  
Minimum Value ◽  
Chinese Hamster Cell Line

The generation time of a Chinese hamster cell line was varied by the use of different lots of sera in the culture media. Analysis of the division waves following thymidine synchronization showed that lengthening of the generation time was a result of an increase in duration of the G1 phase and that thymidine treatment reduced the duration of G1 back to its minimum value.

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.

DNA-mediated transfer of a human DNA repair gene that controls sister chromatid exchange

1985 ◽  
Vol 5 (4) ◽  
pp. 881-884
Author(s):  
L H Thompson ◽  
K W Brookman ◽  
J L Minkler ◽  
J C Fuscoe ◽  
K A Henning ◽  
...  
Keyword(s):  
Sister Chromatid ◽  
Sister Chromatid Exchange ◽  
Human Fibroblasts ◽  
Chinese Hamster ◽  
Chinese Hamster Cell ◽  
Repair Gene ◽  
Dna Repair Gene ◽  
Chinese Hamster Cell Line ◽  
Dna Strand ◽  
Repair Defect

The Chinese hamster cell line mutant EM9, which has a reduced ability to repair DNA strand breaks, is noted for its highly elevated frequency of sister chromatid exchange, a property shared with cells from individuals with Bloom's syndrome. The defect in EM9 cells was corrected by fusion hybridization with normal human fibroblasts and by transfection with DNA from hybrid cells. The transformants showed normalization of sister chromatid exchange frequency but incomplete correction of the repair defect in terms of chromosomal aberrations produced by 5-bromo-2'-deoxyuridine.

Presence or absence of a G1 period in the cell cycle and growth control in a Chinese hamster cell line

1985 ◽  
Vol 158 (1) ◽  
pp. 276-279 ◽  
Author(s):  
D. Wynford-Thomas ◽  
G. Marin ◽  
A. LaMontagne ◽  
David M. Prescott
Keyword(s):  
Cell Cycle ◽  
Cell Line ◽  
Chinese Hamster ◽  
Growth Control ◽  
Chinese Hamster Cell ◽  
Chinese Hamster Cell Line

THE ESTABLISHMENT AND CHROMOSOME ANALYSIS OF A NEW CELL LINE OF CHINESE HAMSTER FROM SPONTANEOUS TRANSFORMATION IN VITRO

1971 ◽  
Vol 13 (1) ◽  
pp. 9-13 ◽  
Author(s):  
C. C. Lin ◽  
T. D. Chang ◽  
Virginia Niewczas-Late
Keyword(s):  
Cell Line ◽  
Chinese Hamster ◽  
Chromosome Analysis ◽  
Cell Types ◽  
Selective Advantage ◽  
Chinese Hamster Cell ◽  
Major Type ◽  
Spontaneous Transformation ◽  
Chinese Hamster Cell Line

A male Chinese hamster cell line has been established through spontaneous transformation in a skin culture. Chromosome studies at passage 13 revealed one major and one minor type of pseudodiploid cells (77.3 and 20%). At passage 42, only the major subline persisted (78%). The two sublines, especially the major one, had selective advantage over other cell types in this cell line probably because they were more nearly genetically balanced. Autoradiographic studies indicated no overall increase in late replicating chromosomal elements in the two sublines. Both cell types lacked the X chromosome and chromosome 6, but they were largely compensated for by the presence of new marker chromosomes. However, more chromosomal material was missing in the minor type than in the major type, and this may account for the lower adaptability of the former.

Multiple origins of replication in the dihydrofolate reductase amplicons of a methotrexate-resistant chinese hamster cell line

1990 ◽  
Vol 10 (4) ◽  
pp. 1338-1346
Author(s):  
C Ma ◽  
T H Leu ◽  
J L Hamlin
Keyword(s):  
Cell Line ◽  
Dihydrofolate Reductase ◽  
Chinese Hamster ◽  
Chinese Hamster Cell ◽  
Ovary Cell ◽  
Multiple Origins ◽  
Chromosomal Walking ◽  
Chinese Hamster Cell Line ◽  
S Period ◽  
Ovary Cell Line

We recently showed that replication initiates in the early S period at two closely spaced zones in the 240-kilobase (kb) dihydrofolate reductase (DHFR) amplicon of the methotrexate-resistant Chinese hamster ovary cell line CHOC 400. Both of these initiation loci (ori-beta and ori-gamma) have previously been cloned in a recombinant cosmid. In this study, we identified a third early-firing initiation locus (ori-alpha) in the much larger DHFR amplicon of the independently isolated methotrexate-resistant Chinese hamster cell line DC3F-A3/4K (A3/4K). We describe the molecular cloning of this newly identified locus and demonstrate by chromosomal walking that ori-alpha lies approximately 240 kb upstream from ori-beta. Using overlapping cosmid clones for more than 450 kb of DNA sequence from this region of the DHFR domain, we have monitored the replication pattern of the amplicons in synchronized A3/4K cells. These studies suggest that ori-alpha, ori-beta, and ori-gamma are the only early-firing initiation sites in this 450-kb sequence. In addition, we have been able to roughly localize the termini between ori-alpha and ori-beta and between ori-alpha and the next origin in the 5' direction. Thus, we have now isolated the equivalent of three early-firing replicons (including their origins) from a well-characterized chromosomal domain. With these tools, it should be possible to determine those properties that are shared by the origins and termini of different replicons and which are therefore likely to be functionally significant.

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