Over 600 temperature-sensitive mutants of B. subtilis were isolated at random from Nitroso-guanidine-treated cells. Mutants defective in DNA synthesis (ts DNA mutants) were identified by determining the ratio of the amount of protein to DNA synthesized at 45°C. Thirty-eight mutants were specifically inhibited in DNA synthesis. Genetic analysis by transformation of 29 of these ts DNA mutants shows that they are distributed in 4 small linkage groups designated A, B, C and D. By transduction it is shown that these groups are located in different regions of the B. subtilis genetic map. The following physiological properties at 45°C of 27 ts DNA mutants were determined: residual DNA and protein synthesis, viability, PBSX induction and morphology. After cessation of DNA synthesis at 45°C mutant cells of groups A and C elongate but cannot divide, whereas U and D group mutant cells do divide and produce anucleate cells. Preliminary experiments suggest that at 45°C B and D group mutants complete all current rounds of replication but cannot initiate new ones.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:623065 |
| Date | January 1968 |
| Creators | Karamata, Dimitrije |
| Publisher | Imperial College London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/10044/1/15914 |
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