ISSN:
0021-9541
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
Both chick embryo fibroblasts and mouse 3T3 cells reduce the rate at which they incorporate H3 uridine into RNA as their growth becomes inhibited at high cell density. This reduction occurs as a function of the cell population density, and with chick embryo cells (in contrast to 3T3 cells) it is not accompanied by significant medium alterations. This indicates the importance of the cell population density in the control of cellular metabolism.The decline in H3 uridine incorporation is paralleled by a decline in the rate of uptake of the isotope into the acid-soluble pool, suggesting that decreased entry of H3 uridine into the cell, rather than a decreased rate of RNA synthesis, is responsible for the reduced rate of incorporation into RNA of density-inhibited cells. This suggestion was confirmed by finding that when the restriction on uridine uptake was overcome by increasing the concentration of uridine in the medium, the density-dependent inhibition of uridine incorporation was largely reversed. We conclude that, even though the rate of H3 uridine incorporation into RNA is reduced three- to five-fold in density-inhibited cells, the rate of synthesis of pulse-labeled RNA continues at 70 to 85% of the rapidly-growing rate.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcp.1040770205
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