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Title: DNA replication in Schizosaccharomyces pombe
Author: Nasmyth, Kim
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1977
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The primary aim of this thesis was to isolate temperature sensitive genetic mutants of Schizosaccharomyces pombe which are defective in DNA replication. 30 presumptive. (DNA) mutants were isolated after nitrosoguanidine mutagenesis on the basis of their having a defect in the S phase period of the cell cycle. The mutations are all recessive and were allocated to 9 unlinked nuclear genes (cde 10, 17, 18, 19, 20, 21, 22, 23, 24). Physiological characterization revealed that (1) Mutants of cdc 10, 20, 22 are probably defective in the initiation of S phase, (2) mutants of cdc 21, 23 are defective in the process of DNA synthesis, (3) mutants of cdc 18, 19 are not defective in bulk DNA synthesis and their to functions are completed prior to or independently of S phase at the permissive temperature, and (4) mutants of cdc 17, 2.4 are not defective in bulk DNA synthesis but their is functions cannot be completed at the permissive temperature if DNA synthesis is inhibited by hydro urea. cdc 17-K42 possesses 41 major thermo-sensitive phenotypes: a is lethality, sensitivity, a defect in the joining of nascent DNA strands, and an abnormally high level of DNA ligase. The DNA ligase assays suggest that this mutation is located in the structural gene for DNA ligase. Mutants of cdc 24 are also defective in the joining of nascent tWA strands, but at a much higher molecular weight level. The secondary aim of this thesis was an analysis of the control of S phase in S. pombe. This was investigated by growth of cells under nitrogen limitation in a chemostat at different growth rates. Only the bl phase of the cell cycle is extended as the generation time is increased under these conditions. The initiation of DNA replication may be dependent on the cell attaining a critical size. Several techniques necessary for a study of DNA replication in S. pombe were specially developed during this work.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available