Hiroshi Terano

Resistance of DNA against Radiation-Induced Strand Breakage in Bacterial Spores

TANOOKA, H. and TERANO, H. Resistance of DNA against RadiationInduced Strand Breakage in Bacterial Spores. Radiat. Res. 43, 613-626, (1970). Single- and double-strand breaks of DNA in electron-irradiated Bacillus subtilis spores were measured and compared with those in irradiated vegetative cells by zone sedimentation in alkaline and neutral pH sucrose gradients. DNA in spores was much more resistant to both types of damage than DNA in vegetative cells. Induction of one single-strand break in DNA of spore genome required 2.8 krad compared to 0.13 krad in vegetative cell genome. In other terms, energies of 857 eV in spore DNA and 41 eV in vegetative cell DNA were required to induce one single-strand break, calculated from molecular weights given by weight-average sedimentation distances; or 835 eV and 46 eV, calculated from weight-average molecular weights. The resistance of DNA was maintained after spores were converted to osmotically sensitive spheroplasts; however, the resistance was lost by rupture of the spheroplast structure. This resistance of DNA was not due to the repair activity of spores nor to protective substance in spore

Increase of thymidine, thymidylate and deoxycytidine kinase activities during germination of bacterial spores

Abstract 1. 1. Very low activities of thymidine kinase (ATP: thymidine 5′-phosphotransferase, EC 2.7.1.21), thymidylate kinase (ATP: 5′-thymidylic acid phosphotransferase) and deoxycytidine kinase (ATP: deoxycytidine 5′-phosphotransferase) were found in crude extracts from bacterial spores as compared with those from vegetative cells. This was repeatedly confirmed by applying various extraction methods. 2. 2. Activities of thymidine kinase and deoxycytidine kinase increased during germination of spores simultaneously with the initiation of DNA synthesis, but the increase of thymidylate kinase activity was delayed. 3. 3. The correlation between the increase of kinase activities and the rate of DNA synthesis was seen in spores germinated in starved as well as in complete conditions. This correlation, however, was not held in germination of heavily irradiated spores, suggesting that the formation of the kinases is under different control from that for DNA polymerization in cells. 4. 4. The increase in the kinase activities was inhibited by 100 μg/ml of chloramphenicol, indicating de novo formation of the kinases. By delayed addition of chloramphenicol the kinases were distinguished from early proteins synthesized during the first 30–80 min of germination. 5. 5. The possibilities that an inhibitor of thymidine kinase is present in spores and that a thymidine kinase activator is present in vegetative cells were eliminated.

Germination-induced repair of single-strand breaks of DNA in irradiated Bacillus subtilis spores

Abstract The single-strand breaks produced in DNA of B. subtilis spores by ionizing radiation were repaired during germination in the absence of normal DNA synthesis. This repair did not occur unless the initial stage of germination was induced.