Biomaterial Database

Action of ionizing radiation on sensitive strains of Escherichia coli B. 1972

E C Pollard, and A Tilberg

Strain B(8-11) has been found to be very sensitive to postirradiation DNA degradation. Up to 98% of the DNA is degraded at optimum doses. The amount of residual DNA correlates with the retention of colony-forming ability (CFA). Studies of rates of degradation as a function of dose agree with the concept that a degrading lesion causes a definite rate of degradation and that increased numbers of lesions produce proportionally faster rates. By observing the burst size of T7 phage which uses host DNA it has been established that DNA degradation occurs in an all-or-nothing fashion in a unit which is present two or three times per cell. Degradation is enzymatic and the enzyme system is already present in the cell as evidenced by the rapid onset of degradation. DNA synthesis continues in cells that have lost some chromosomes by degradation. Single-cell division patterns show that recovery from "sublethal" damage can occur even in this sensitive cell. Recovery in preirradiation oxygenated cells differs from that in nitrogenated cells.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008433	Mathematics	The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Mathematic
D009584	Nitrogen	An element with the atomic symbol N, atomic number 7, and atomic weight [14.00643; 14.00728]. Nitrogen exists as a diatomic gas and makes up about 78% of the earth's atmosphere by volume. It is a constituent of proteins and nucleic acids and found in all living cells.
D010100	Oxygen	An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.	Dioxygen,Oxygen-16,Oxygen 16
D011829	Radiation Dosage	The amount of radiation energy that is deposited in a unit mass of material, such as tissues of plants or animal. In RADIOTHERAPY, radiation dosage is expressed in gray units (Gy). In RADIOLOGIC HEALTH, the dosage is expressed by the product of absorbed dose (Gy) and quality factor (a function of linear energy transfer), and is called radiation dose equivalent in sievert units (Sv).	Sievert Units,Dosage, Radiation,Gray Units,Gy Radiation,Sv Radiation Dose Equivalent,Dosages, Radiation,Radiation Dosages,Units, Gray,Units, Sievert
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
D002247	Carbon Isotopes	Stable carbon atoms that have the same atomic number as the element carbon but differ in atomic weight. C-13 is a stable carbon isotope.	Carbon Isotope,Isotope, Carbon,Isotopes, Carbon
D002470	Cell Survival	The span of viability of a cell characterized by the capacity to perform certain functions such as metabolism, growth, reproduction, some form of responsiveness, and adaptability.	Cell Viability,Cell Viabilities,Survival, Cell,Viabilities, Cell,Viability, Cell
D003036	Cobalt Isotopes	Stable cobalt atoms that have the same atomic number as the element cobalt, but differ in atomic weight. Co-59 is a stable cobalt isotope.	Isotopes, Cobalt
D003090	Coliphages	Viruses whose host is Escherichia coli.	Escherichia coli Phages,Coliphage,Escherichia coli Phage,Phage, Escherichia coli,Phages, Escherichia coli