The effects of in vitro age and culture state on histone variant synthesis in human diploid fibroblasts

✍ Scribed by R. T. Dell'Orco; M. I. Worthington

• Publisher: John Wiley and Sons
• Year: 1988
• Tongue: English
• Weight: 822 KB
• Volume: 136
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1041360122

✦ Synopsis

Histone variant synthesis patterns from human diploid fibrobladike cells of different in vitro ages were determined during exponential growth, at confluence, and during low serum arrest. The results are reported as the ratios of H2A variant synthesis (H2A.1 and HZA.2iH2A.x and H2A.z) and H3 variant synthesis (H3.1 and H3.2iH3.3) that have been used to characterize individual cell cycle states. Hydroxyurea was employed in some experiments to reduce S phase cells. The results indicate that high population doubling level (PDL) cells move through the GI phase of the division cycle during exponential growth and exist in the GO cell cycle state at confluence and during low serum arrest. Low PDL cells, however, exist in the C1 cell cycle state at confluence and revert to a GO state only after maintenance as quiescent populations. This would suggest that when stimulated high PDL cells cannot enter into S phase, they revert to a GO cell cycle state.