Health & Environmental Research Online (HERO)


Print Feedback Export to File
1627721 
Journal Article 
Molecular dosimetry of chemical mutagens: Measurement of molecular dose and DNA repair in mammalian germ cells 
Sega, GA 
1976 
1 
Mutation Research
ISSN: 0027-5107
EISSN: 1873-135X 
HEEP/78/03784 
38 
5 
317-326 
HEEP COPYRIGHT: BIOL ABS. The results from the study of the duration of DNA repair in early spermatids of the mouse after treatment with MMS, (methyl methanesulfonate), EMS (ethyl mathanesulfonate, PMS (propyl methanesulfonate) and IMS (isopropyl methanesulfonate) indicate that as long as 3 days after exposure to these chemicals the early spermatid stages are still undergoing measurable DNA repair. This extended repair is not due to continuing alkylation of the DNA during this time period, because these 4 chemical homologs are quite reactive in aqueous solutions and even more reactive in biological systems, probably disappearing within several hours, at most, after injection. For MMS and EMS there is a rapid decrease in the level of DNA repair in the early spermatids in the first half-day following treatment. This is followed by a much slower, exponential decrease in the level of repair out to 3 days post-treatment. The amount of repair occurring between 1/2 and 3 days post-treatment is apparently simply proportional to the number of repairable lesions still present in the DNA. The half-life for the DNA repair occurring between 1/2 and 3 days post-treatment with MMS and EMS is between 1 and 3 days.