Effect of inhibition of synthesis in the S-period on the subsequent course of mitosis in a synchronized chinese hamster cell culture

1979 ◽  
Vol 87 (3) ◽  
pp. 281-284
Author(s):  
L. S. Strochkova
Keyword(s):  
Cell Culture ◽  
Chinese Hamster ◽  
Chinese Hamster Cell ◽  
S Period

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.

scholarly journals 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.

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.

Production of Recombinant Proteins in Chinese Hamster Ovary Cells Using A Protein-Free Cell Culture Medium

1995 ◽  
Vol 13 (4) ◽  
pp. 389-392 ◽  
Author(s):  
Michael Zang ◽  
Helmut Trautmann ◽  
Christine Gandor ◽  
Ferruccio Messi ◽  
Fred Asselbergs ◽  
...  
Keyword(s):  
Cell Culture ◽  
Recombinant Proteins ◽  
Chinese Hamster Ovary ◽  
Culture Medium ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Free Cell ◽  
Cell Culture Medium ◽  
Ovary Cells
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