TABLE 2.
Requirement of hY RNAs for DNA replication in late-G1-phase nuclei from mouse NIH 3T3 cells
| Replication in vitro witha: | % of nuclei replicatingb |
|---|---|
| Buffer (elongation) | 4.6 ± 4 |
| S cytosol (initiation and elongation) | 28.3 ± 4.1 |
| S cytosol plus: | |
| RNase A | 5.3 ± 3.6 |
| Nontarget DNA oligonucleotide | 24.2 ± 4.8 |
| Anti-hY3 DNA oligonucleotide | 3.3 ± 1.4 |
| Anti-hY3 oligonucleotide + hY1 RNA | 30.8 ± 5.1 |
a
Nuclei were prepared from mouse NIH 3T3 cells, synchronized in late G1 phase by a release from quiescence for 18 h (34). Semiconservative DNA replication is initiated in these nuclei upon incubation in cytosolic extract from S-phase cells in vitro (5, 34).
b
We used 300 μg of protein of S cytosol from HeLa cells and 300 ng of hY1 RNA per reaction as indicated in the text. Mean values ± standard deviations of the means from three to five independent experiments are shown.