Specific Activity of [3H]ara-C or [3H]dCyd in DNA of Growing CCRF-CEM Cells
| Nucleoside . | UV (J/m2) . | DNA-Specific Activity . | Repair/Replication3-150 . | |
|---|---|---|---|---|
| . | . | (dpm/UV absorbance unit) . | . | |
| . | . | Repair . | Replication . | . |
| [3H]ara-C | 0 | 11,159 | 7,599 | 1.47 |
| [3H]ara-C | 10 | 15,014 | 4,939 | 3.04 |
| [3H]dCyd | 0 | 336,847 | 185,361 | 1.82 |
| [3H]dCyd | 10 | 416,356 | 154,642 | 2.69 |
| Nucleoside . | UV (J/m2) . | DNA-Specific Activity . | Repair/Replication3-150 . | |
|---|---|---|---|---|
| . | . | (dpm/UV absorbance unit) . | . | |
| . | . | Repair . | Replication . | . |
| [3H]ara-C | 0 | 11,159 | 7,599 | 1.47 |
| [3H]ara-C | 10 | 15,014 | 4,939 | 3.04 |
| [3H]dCyd | 0 | 336,847 | 185,361 | 1.82 |
| [3H]dCyd | 10 | 416,356 | 154,642 | 2.69 |
Each experiment was performed with exponentially growing CCRF-CEM cells labeled for 13 hours 1.5 × 10−2 μCi/mL of [3H]ara-C (0.6 nmol/L) and 0.2 μCi/mL of [3H]dCyd (4 nmol/L) with or without 10 J/m2 UV irradiation. The peak of incorporation of [3H]ara-C or [3H]dCyd into DNA was measured using alkaline CsCl density-gradient ultracentrifugation. The intermediate-density peak between fractions 28 and 39 was regarded as repair, and the high-density peak between fractions 40 and 53 as replication. The total dpm was divided by the sum of UV absorption at 260 nm in each set of fractions. DNA-specific activity in fractions located at the repair or replication peak was indicated in this table.
The ratio of the repair and replication values.