Biomaterial Database

[Structure of the DNA molecule in the course of reparation process after ultraviolet irradiation of E. coli cells]. 1975

V P Osakovskiĭ, and V K Ravin

Kinetics was studied of DNA degradation, processing and synthesis in the course of post-radiation incubation (irradiation dose 0-2000 erg/mm2). It has been shown that contrary to the endonuclease splitting of DNA strands, DNA degradation requires energy. DNA degradation is not enhanced upon an increase of the irradiation up to 400 erg/mm2 and more and at the incubation duration exceeding 120 min. The degradation involves not more than 40% of the total DNA quantity. It takes place in the absence of resynthesis registered by the incorporation of [3h] thymidine and 32P and dephinylamine reaction. The number of single-strand breaks in DNA (per one E. coli chromosome strans) reaches a maximum value after 120-180 min. of incubation. This maximal value is linearily increased upon an increase of the irradiation dose from 0 to 1200 erg/mm2 and does not change when the dose increases further. The number of single-strand breaks does not exceed 35-50, this value being dependent on the presence of glucose. On the basis of the data obtained a suggestion is put forward that in the course of the reparative degradation of DNA, prolonged (10(4)-10(5) nucleotides) single-stranded regions are formed. Possible role of these 'nicks" in the appearance of mutations is discussed.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D011830	Radiation Effects	The effects of ionizing and nonionizing radiation upon living organisms, organs and tissues, and their constituents, and upon physiologic processes. It includes the effect of irradiation on food, drugs, and chemicals.	Effects, Radiation,Effect, Radiation,Radiation Effect
D004260	DNA Repair	The removal of DNA LESIONS and/or restoration of intact DNA strands without BASE PAIR MISMATCHES, intrastrand or interstrand crosslinks, or discontinuities in the DNA sugar-phosphate backbones.	DNA Damage Response
D004269	DNA, Bacterial	Deoxyribonucleic acid that makes up the genetic material of bacteria.	Bacterial DNA
D004277	DNA, Single-Stranded	A single chain of deoxyribonucleotides that occurs in some bacteria and viruses. It usually exists as a covalently closed circle.	Single-Stranded DNA,DNA, Single Stranded,Single Stranded DNA
D004307	Dose-Response Relationship, Radiation	The relationship between the dose of administered radiation and the response of the organism or tissue to the radiation.	Dose Response Relationship, Radiation,Dose-Response Relationships, Radiation,Radiation Dose-Response Relationship,Radiation Dose-Response Relationships,Relationship, Radiation Dose-Response,Relationships, Radiation Dose-Response
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli