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DNA synthesis and mitosis in a temperature sensitive Chinese hamster cell line

✍ Scribed by D. H. Roscoe; Hildred Robinson; A. W. Carbonell


Publisher
John Wiley and Sons
Year
1973
Tongue
English
Weight
407 KB
Volume
82
Category
Article
ISSN
0021-9541

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✦ Synopsis


Abstract

Viability, DNA synthesis and mitosis have been followed in the temperature sensitive Chinese hamster cell mutant K12 under permissive and non‐permissive conditions. On incubation at 40°C cells retained their ability to form colonies at 33°C for 15 to 20 hours, but viability was lost gradually during the following 20 hours. When random cultures of K12 were shifted to 40°C the rate of DNA synthesis was normal for three to four hours but then decreased markedly, reaching 95% inhibition after 24 hours. Under the same conditions mitosis was inhibited after 15 hours. If cultures which had been incubated at 40°C for 16 hours were placed at 33°C the rate of DNA synthesis increased five hours after the shift down and mitosis 18 hours after. These results can be interpreted on the assumption that K12 at 40°C is unable to complete a step in the cell cycle which is essential for DNA synthesis and which occurs three to four hours before the start of S at 33°C.


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