A respiration-deficient Chinese hamster cell line with a defect in mitochondrial protein synthesis: Rapid turnover of some mitochondrial transcripts

1997 ◽  
Vol 23 (1) ◽  
pp. 27-35 ◽  
Author(s):  
Harry C. Au ◽  
Immo E. Scheffler
1977 ◽  
Vol 55 (10) ◽  
pp. 1064-1074 ◽  
Author(s):  
R. W. Yatscoff ◽  
K. B. Freeman

Mitochondrial proteins labelled with [35S]methionine for 1 h in whole Chinese hamster ovary (CHO) cells in the presence of cycloheximide or emetine, known inhibitors of cytosolic protein synthesis, have been enumerated and characterized by their electrophoretic mobility in sodium dodecyl sulfate slab gel electrophoresis. Ten distinct electrophoretic bands were observed. The components were relatively stable during a 2 h postlabelling period. The same 10 bands were also seen with the CHO cell line tsH1, labelled at 40 °C, a temperature at which cytosolic but not mitochondrial protein synthesis is inhibited in this cell line, and with isolated mitochondria labelled in the presence of cycloheximide. An 11th band was present when [3H]leucine but not [35S] methionine was used for labelling. The width of the major band suggested that it consists of two components making a total of at least 12 proteins synthesized in mitochondria. The molecular weights of these mitochondrial proteins ranged from 5000 to 50000 and there was a sixfold difference in the relative molar amounts synthesized in a 1-h period in the presence of [3H]leucine or [3SS] methionine.No differences in number or electrophoretic mobility of the mitochondrially synthesized proteins were found among the seven CHO cell lines examined. These results suggest the stability of the mitochondrial genome in the CHO cell line.


Nature ◽  
1977 ◽  
Vol 268 (5615) ◽  
pp. 64-67 ◽  
Author(s):  
G. DITTA ◽  
K. SODERBERG ◽  
I. E. SCHEFFLER

1985 ◽  
Vol 158 (1) ◽  
pp. 276-279 ◽  
Author(s):  
D. Wynford-Thomas ◽  
G. Marin ◽  
A. LaMontagne ◽  
David M. Prescott

1971 ◽  
Vol 13 (1) ◽  
pp. 9-13 ◽  
Author(s):  
C. C. Lin ◽  
T. D. Chang ◽  
Virginia Niewczas-Late

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.


1990 ◽  
Vol 10 (4) ◽  
pp. 1338-1346
Author(s):  
C Ma ◽  
T H Leu ◽  
J L Hamlin

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.


Sign in / Sign up

Export Citation Format

Share Document