The relationship of DNA synthesis to protein accumulation in the cell nucleus

✍ Scribed by G. Auer; A. Zetterberg; G. E. Foley

• Publisher: John Wiley and Sons
• Year: 1970
• Tongue: English
• Weight: 561 KB
• Volume: 76
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1040760313

✦ Synopsis

Abstract

The relationship between DNA synthesis and protein accumulation in cell nucleus and cytoplasm has been investigated by the use of a combination of ultramicrointerferometric and ultramicrospectrophotometric methods.

5‐Fluoro‐2'‐deoxyuridine (FUdR) inhibited DNA synthesis, resulting in inhibition of cell proliferation in G‐1 and early S‐phase. However, synthesis and accumulation of protein continued in the presence of FUdR, as indicated by a 54% increase in the average dry mass value per individual cell during 18‐hour exposure to FUdR; due primarily to protein accumulation in the cytoplasm, the average cytoplasmic dry mass increased by as much as 85%, while the dry mass of the nucleus increased by only 21%.

The dry mass values of individual nuclei were well‐correlated to the nuclear DNA content throughout the period of exposure to FUdR. In contrast to the continued accumulation of protein in the cytoplasm during inhibition of DNA synthesis, protein accumulation in the nucleus was inhibited. When cells were released from inhibition of DNA synthesis by the addition of 2'‐deoxythymidine, the nuclear DNA content and nuclear dry mass increased in near‐synchrony, there being some evidence that DNA synthesis was initiated somewhat prior to initiation of increase in nuclear dry mass.

Thus, it appears that DNA synthesis (or an increase in nuclear DNA content) is intimately related to the regulation of protein accumulation in the nucleus.