sample="quota" bates="2029137905" isource="pm" decade="1980" class="ni" date="19831021" 10-21-83 Roger: CULTURES: I have made up fresh stab and disc cultures for strains TA97, TA102, and TA104 (prepared 10-21-83). There are duplicates of each for TA102 and TA104 since I have had some trouble in setting good isolates with acceptable viability and spontaneous reversion counts. This seems to be a problem that several investigators have had as you will see in some of the information I have sent. So far, I have not tested any positive controls. I have found that platins TA102 viable colonies on Vosel Bonner minimal glucose agar plates with excess histidine does not do as well as on nutrient agar plates. The colonies will eventually grow up to a countable size but it takes several extra days of incubation. I suspect either a nutrient or growth factor deficiency but have not investigated this to any extent except to make the observation. Dororthy Maron cautioned against incubating TA97 and TA102 test plates longer than 48 hours because of the appearance of suppressor mutants. I have included some data (plate incorporation assay) I have obtained with the parent cultures used to make the stab and disc cultures I am sending: these were 10 lower cultures @ 37ºC & 120 rpm Let me know if you find anything interesting with these cultures. Good luck!! Best regards, Karen Rapy Sherwood