Aspects of Radiation-Induced Mutagenesis and Malignant Transformation

1982 ◽  
pp. 217-228 ◽  
Author(s):  
Ethel Moustacchi
Keyword(s):  
Malignant Transformation ◽  
Radiation Induced ◽  
Induced Mutagenesis

Developing a Genetic System in Deinococcus radiodurans for Analyzing Mutations

Genetics ◽  
2004 ◽  
Vol 166 (2) ◽  
pp. 661-668
Author(s):  
Mandy Kim ◽  
Erika Wolff ◽  
Tiffany Huang ◽  
Lilit Garibyan ◽  
Ashlee M Earl ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Deinococcus Radiodurans ◽  
Genetic System ◽  
Base Change ◽  
Base Substitution ◽  
Wild Type ◽  
Base Pairs ◽  
E Coli ◽  
Radiation Induced ◽  
Induced Mutagenesis

Abstract We have applied a genetic system for analyzing mutations in Escherichia coli to Deinococcus radiodurans, an extremeophile with an astonishingly high resistance to UV- and ionizing-radiation-induced mutagenesis. Taking advantage of the conservation of the β-subunit of RNA polymerase among most prokaryotes, we derived again in D. radiodurans the rpoB/Rif r system that we developed in E. coli to monitor base substitutions, defining 33 base change substitutions at 22 different base pairs. We sequenced >250 mutations leading to Rif r in D. radiodurans derived spontaneously in wild-type and uvrD (mismatch-repair-deficient) backgrounds and after treatment with N-methyl-N′-nitro-N-nitrosoguanidine (NTG) and 5-azacytidine (5AZ). The specificities of NTG and 5AZ in D. radiodurans are the same as those found for E. coli and other organisms. There are prominent base substitution hotspots in rpoB in both D. radiodurans and E. coli. In several cases these are at different points in each organism, even though the DNA sequences surrounding the hotspots and their corresponding sites are very similar in both D. radiodurans and E. coli. In one case the hotspots occur at the same site in both organisms.

scholarly journals Coexistence of SOS-Dependent and SOS-Independent Regulation of DNA Repair Genes in Radiation-Resistant Deinococcus Bacteria

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 924
Author(s):  
Laurence Blanchard ◽  
Arjan de Groot
Keyword(s):  
Dna Repair ◽  
Deinococcus Radiodurans ◽  
Dna Repair Genes ◽  
Lesion Bypass ◽  
Radiation Resistant ◽  
Radiation Induced ◽  
Induced Mutagenesis ◽  
High Doses ◽  
Translesion Polymerases ◽  
Repair Genes

Deinococcus bacteria are extremely resistant to radiation and able to repair a shattered genome in an essentially error-free manner after exposure to high doses of radiation or prolonged desiccation. An efficient, SOS-independent response mechanism to induce various DNA repair genes such as recA is essential for radiation resistance. This pathway, called radiation/desiccation response, is controlled by metallopeptidase IrrE and repressor DdrO that are highly conserved in Deinococcus. Among various Deinococcus species, Deinococcus radiodurans has been studied most extensively. Its genome encodes classical DNA repair proteins for error-free repair but no error-prone translesion DNA polymerases, which may suggest that absence of mutagenic lesion bypass is crucial for error-free repair of massive DNA damage. However, many other radiation-resistant Deinococcus species do possess translesion polymerases, and radiation-induced mutagenesis has been demonstrated. At least dozens of Deinococcus species contain a mutagenesis cassette, and some even two cassettes, encoding error-prone translesion polymerase DnaE2 and two other proteins, ImuY and ImuB-C, that are probable accessory factors required for DnaE2 activity. Expression of this mutagenesis cassette is under control of the SOS regulators RecA and LexA. In this paper, we review both the RecA/LexA-controlled mutagenesis and the IrrE/DdrO-controlled radiation/desiccation response in Deinococcus.

scholarly journals Proton beam therapy for malignant transformation of intracranial epidermoid cyst

2019 ◽  
Vol 12 (7) ◽  
pp. e229388
Author(s):  
Zhe Chen ◽  
Masayuki Araya ◽  
Hiroshi Onishi
Keyword(s):  
Proton Beam ◽  
Malignant Transformation ◽  
Epidermoid Cyst ◽  
Clinical Case ◽  
Proton Beam Therapy ◽  
Facial Paresis ◽  
Surgical Interventions ◽  
Radiation Induced ◽  
Intracranial Epidermoid

We report the first clinical case on the successful use of proton beam therapy in the management of malignant transformation of intracranial epidermoid cyst. A 43-year-old man was initially diagnosed as this disease with left facial paresis, hypesthesia and hypoalgesia in the territories of the trigeminal nerve. After failure of surgical interventions, he was referred to our radiation centre. We performed a postoperative proton beam therapy for treatment. We delivered a total dose of 57 GyE in 31 fractions. He tolerated the treatment well with mild acute toxicities and remained healthy and functional by 2-year follow-up postradiotherapy. No evidence of delayed radiation-induced neurotoxicity was observed.

Gamma radiation induced mutagenesis in Aspergillus niger to enhance its microbial fermentation activity for industrial enzyme production

2010 ◽  
Vol 38 (2) ◽  
pp. 1367-1374 ◽  
Author(s):  
M. Siddique Awan ◽  
Nabila Tabbasam ◽  
N. Ayub ◽  
M. E. Babar ◽  
Mehboob-ur-Rahman ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Gamma Radiation ◽  
Enzyme Production ◽  
Microbial Fermentation ◽  
Industrial Enzyme ◽  
Radiation Induced ◽  
Induced Mutagenesis

scholarly journals Recovery of a low mutant frequency after ionizing radiation-induced mutagenesis during spermatogenesis

2008 ◽  
Vol 654 (2) ◽  
pp. 150-157 ◽  
Author(s):  
Guogang Xu ◽  
Gabriel W. Intano ◽  
John R. McCarrey ◽  
Ronald B. Walter ◽  
C. Alex McMahan ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Radiation Induced ◽  
Induced Mutagenesis ◽  
Mutant Frequency
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