Mitochondrial DNA synthesis in mouse L cells temperature sensitive in nuclear DNA replication.

Temperature-sensitive (ts) A 1S9 mouse L cells continue to synthesize double-stranded covalently closed mitochondrial (mt) DNA at a temperature (38.5 degrees C) which is nonpermissive for chromosomal DNA replication. The amount of mt DNA made appears to be quantitatively linked to nuclear DNA synthesis. Nuclear DNA replication proceeds normally for 6-8 h after the cells are shifted to 38.5 degrees C, and then declines to reach a minimum at 20-24 h. The level of mt DNA synthesis remains high during this period and decreases once the ts lesion has been established.