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Dynamics of the Bac...
Dynamics of the Bacterial Genome : Rates and Mechanisms of Mutation
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- Koskiniemi, Sanna, 1980- (författare)
- Uppsala universitet,Institutionen för medicinsk biokemi och mikrobiologi,Dan Andersson
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- Andersson, Dan, Dr (preses)
- Uppsala universitet,Institutionen för medicinsk biokemi och mikrobiologi
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- Hughes, Diarmaid, Dr (preses)
- Uppsala universitet,Institutionen för cell- och molekylärbiologi
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- Matic, Ivan, Dr (opponent)
- Génétique Moléculaire Evolutive et Médicale
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(creator_code:org_t)
- ISBN 9789155476878
- Uppsala : Acta Universitatis Upsaliensis, 2010
- Engelska 56 s.
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Serie: Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, 1651-6206 ; 509
- Relaterad länk:
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https://uu.diva-port... (primary) (Raw object)
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https://urn.kb.se/re...
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Abstract
Ämnesord
Stäng
- Bacterial chromosomes are highly dynamic, continuously changing with respect to gene content and size via a number of processes, including deletions that result in gene loss. How deletions form and at what rates has been the focus of this thesis. In paper II we investigated how chromosomal location affects chromosomal deletion rates in S. typhimurium. Deletion rates varied more than 100-fold between different chromosomal locations and some large deletions significantly increased the exponential growth rate of the cells. Our results suggest that the chromosome is heterogeneous with respect to deletion rates and that deletions may be genetically fixed as a consequence of natural selection rather than by drift or mutational biases. In paper I we examined in a laboratory setting how rapidly reductive evolution, i.e. gene loss, could occur. Using a serial passage approach, we showed that extensive genome reduction potentially could occur on a very short evolutionary time scale. For most deletions we observed little or no homology at the deletion endpoints, indicating that spontaneous deletions often form through a RecA independent process. In paper III we examined further how large spontaneous deletions form and, unexpectedly, showed that 90% of all spontaneous chromosomal deletions required error-prone translesion DNA polymerases for their formation. We propose that the translesion polymerases stimulate deletion formation by allowing extension of misaligned single-strand DNA ends. In paper IV we investigated how the translesion DNA polymerase Pol IV, RpoS and different types of stresses affect mutation rates in bacteria. Derepression of the LexA regulon caused a small to moderate increase in mutation rates that was fully dependent on functional endonucleases but only partly dependent on translesion DNA polymerases. RpoS levels and growth stresses had only minor effects on mutation rates. Thus, mutation rates appear very robust and are only weakly affected by growth conditions and induction of translesion polymerases and RpoS.
Ämnesord
- MEDICIN OCH HÄLSOVETENSKAP -- Medicinska och farmaceutiska grundvetenskaper -- Mikrobiologi inom det medicinska området (hsv//swe)
- MEDICAL AND HEALTH SCIENCES -- Basic Medicine -- Microbiology in the medical area (hsv//eng)
Nyckelord
- bacteria
- bacterial evolution
- genome reduction
- gene loss
- serial passage
- DNA homology
- tranlesion DNA polymerase
- stress
- Microbiology
- Mikrobiologi
- Bacteriology
- Bakteriologi
- Evolutionary Genetics
- Evolutionär genetik
- Mikrobiologi
- Microbiology
Publikations- och innehållstyp
- vet (ämneskategori)
- dok (ämneskategori)
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