DNA Synthesis and Incorporation of P32 in Irradiated Ehrlich Ascites Cells.

Publisher Website
Google Scholar
Abstract
Experiments were carried out 4-6 days after inoculation of approximately 2 x 107 Ehrlich ascites tumor cells in mice. When the 2-hour incorporation of P32 into DNA was measured at various times after irradiation (800 r total body X-irradiation), no significant depression in DNA specific activity was seen until 1 day. Mean cell volume, mean DNA content per cell, and mean total nucleic acid content per cell at 13 and 20 hours increased at approximately the same rate, closely matching the growth rate of the unirradiated tumor and rate of DNA formation estimated from the incorporation data. Increased DNA content per nucleus after radiation was confirmed by Feulgen microspectro-photometry. At 48 hours after irradiation cell volume and total nucleic acid per cell had risen even higher while DNA per cell showed little further increase. Data suggest that irradiated cells continue to synthesize DNA until they reach the premitotic DNA content (octoploid in Ehrlich cells) and are arrested there because they are unable to go through mitosis.