Biomaterial Database

Discovery of numerous clusters of spontaneous mutations in the specific-locus test in mice necessitates major increases in estimates of doubling doses. 1998

P B Selby

Life Sciences Division, Oak Ridge National Laboratory, TN 37830-6480, USA.

Both the precision with which mutations can be quickly identified and the extensive application of the method make results from specific-locus experiments in mice especially important for estimating the doubling dose, which is the radiation exposure that induces a mutation frequency equal to the total spontaneous mutation frequency per generation. Because of gonadal mosaicism and the mechanism by which it occurs, the frequency with which new spontaneous mutations occur per generation is much higher than has been thought. While it will be some time before many of the newly-apparent uncertainties related to understanding this phenomenon can be resolved, consideration of what is known suggests that it would already be reasonable to raise the doubling dose from 1 to 5 Gy for low-dose-rate exposures to X and gamma radiation. Doing so would reduce risk estimates made by the doubling-dose method fivefold. Because the doubling dose for chemical mutagens is also calculated by division of the total spontaneous mutation frequency per generation by the induced mutation frequency per unit of chemical exposure, hereditary risks for chemicals have also been considerably overestimated if they are based on specific-locus data.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008957	Models, Genetic	Theoretical representations that simulate the behavior or activity of genetic processes or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.	Genetic Models,Genetic Model,Model, Genetic
D009030	Mosaicism	The occurrence in an individual of two or more cell populations of different chromosomal constitutions, derived from a single ZYGOTE, as opposed to CHIMERISM in which the different cell populations are derived from more than one zygote.
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D002874	Chromosome Mapping	Any method used for determining the location of and relative distances between genes on a chromosome.	Gene Mapping,Linkage Mapping,Genome Mapping,Chromosome Mappings,Gene Mappings,Genome Mappings,Linkage Mappings,Mapping, Chromosome,Mapping, Gene,Mapping, Genome,Mapping, Linkage,Mappings, Chromosome,Mappings, Gene,Mappings, Genome,Mappings, Linkage
D003198	Computer Simulation	Computer-based representation of physical systems and phenomena such as chemical processes.	Computational Modeling,Computational Modelling,Computer Models,In silico Modeling,In silico Models,In silico Simulation,Models, Computer,Computerized Models,Computer Model,Computer Simulations,Computerized Model,In silico Model,Model, Computer,Model, Computerized,Model, In silico,Modeling, Computational,Modeling, In silico,Modelling, Computational,Simulation, Computer,Simulation, In silico,Simulations, Computer
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
D005260	Female		Females
D005720	Gamma Rays	Penetrating, high-energy electromagnetic radiation emitted from atomic nuclei during NUCLEAR DECAY. The range of wavelengths of emitted radiation is between 0.1 - 100 pm which overlaps the shorter, more energetic hard X-RAYS wavelengths. The distinction between gamma rays and X-rays is based on their radiation source.	Gamma Wave,Gamma Radiation,Nuclear X-Rays,Radiation, Gamma,X-Rays, Nuclear,Gamma Radiations,Gamma Ray,Gamma Waves,Nuclear X Rays,Nuclear X-Ray,Ray, Gamma,Wave, Gamma,Waves, Gamma,X Rays, Nuclear,X-Ray, Nuclear
D005799	Genes, Dominant	Genes that influence the PHENOTYPE both in the homozygous and the heterozygous state.	Conditions, Dominant Genetic,Dominant Genetic Conditions,Genetic Conditions, Dominant,Condition, Dominant Genetic,Dominant Gene,Dominant Genes,Dominant Genetic Condition,Gene, Dominant,Genetic Condition, Dominant