Abstract:
PURPOSE:This study was undertaken to understand the roles of RecA and RecF proteins in strand break rejoining and maintenance of fidelity of the process following exposure of E. coli to gamma-radiation in vivo. MATERIALS AND METHODS:A plasmid DNA construct, pMTa4, was transformed into isogenic repair proficient (wild) and deficient (recF and recA) E. coli strains and gamma-irradiated up to 30 Gy in vivo. The plasmid DNA was isolated under repair non-permissive (R-)and permissive (R+) conditions and analyzed by gel electrophoresis for the yields of single strand breaks (SSB) and double strand breaks (DSB) and their repair. The clonogenic survival of the E. coli was also recorded. The effects of gamma-irradiation on recA reconstituted with cell free extract of wild strain or ultra-violet (UV)-irradiation were also monitored. RESULTS:None of the strains used in this investigation showed effects of radiation-induced oxidative base damage. The dose dependent increase in SSB and DSB on pMTa4 in wild and recF mutants in R- condition were abolished upon repair incubation. The recA mutant exhibited a disturbed yield of SSB and DSB along with formation of gamma-radiation-induced 'ladder'. The 'ladder' was not observed after repair incubation, UV-irradiation or gamma-irradiation in presence of cell-free extract of wild strain. The survival of recA mutants was seriously compromised. CONCLUSIONS:Wild, recF and recA strains of E. coli could repair gamma-irradiation-induced oxidative damage to base or nucleotide (NT) in vivo. In absence of either RecA or RecF proteins, efficiency of rejoining of strand went down; RecA proteins seemed more critical than RecF in this. High fidelity or correct rejoining of strand breaks, on the other hand, seemed to require simultaneous presence of both RecA and RecF proteins.
journal_name
Int J Radiat Bioljournal_title
International journal of radiation biologyauthors
Sharan RN,Ryo H,Nomura Tdoi
10.1080/09553000601121140subject
Has Abstractpub_date
2007-02-01 00:00:00pages
89-97issue
2eissn
0955-3002issn
1362-3095journal_volume
83pub_type
杂志文章abstract:PURPOSE:γ-rays (IR) cause an increase in intracellular calcium [Ca(2+)], alters contractility and triggers apoptosis via the activation of protein kinase C in intestinal guinea pig smooth muscle cells. The present study investigated the role of the mitochondria in these processes and characterized proteins involved in ...
journal_title:International journal of radiation biology
pub_type: 杂志文章
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journal_title:International journal of radiation biology
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journal_title:International journal of radiation biology
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journal_title:International journal of radiation biology
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更新日期:2020-09-22 00:00:00
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journal_title:International journal of radiation biology
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doi:10.1080/09553009214552451
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更新日期:2003-04-01 00:00:00
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更新日期:2002-11-01 00:00:00