title: Effect of storage at 4 degrees on prepared Salmonella/microsome test plates.
abstract: Salmonella/microsome soft-agar overlay ('Ames' test) plates were prepared using the previously published 'York' method. Plates treated with either added 3-methylcholanthrene (3MC) or 3,3'-dichlorobenzidine (DCB) and Aroclor-induced rat-liver S9 were stored at 4 degrees after preparation and removed at time intervals thereafter for incubation at 37 degrees. The number of 3MC-induced mutants in TA100 fell within 24 h of storage by 50% but then remained at this level until 96 h. Storage for a total of 336 h still showed some residual mono-oxygenase activity. On the other hand the ability to convert DCB to a mutagen for TA98 appeared to increase with storage, reaching a peak by 96 h. After this time the number of induced mutants fell until by 336 h the numbers were approximately equal to those plates which had not been stored in the cold.
mesh_terms: D015101:3,3'-Dichlorobenzidine / Q000633:toxicity*; D000818:Animals; D001560:Benzidines / Q000633:toxicity*; D001711:Biotransformation; D003080:Cold Temperature; D003470:Culture Media; D008748:Methylcholanthrene / Q000633:toxicity*; D008862:Microsomes, Liver / Q000378:metabolism; D009152:Mutagenicity Tests / Q000379:methods*; D009153:Mutagens; D009154:Mutation; D051381:Rats; D013997:Time Factors
chemical_list: D001560:Benzidines; D003470:Culture Media; D009153:Mutagens; D015101:3,3'-Dichlorobenzidine; D008748:Methylcholanthrene