Figure 7-4. Illumination apparatus for the inactivation of cells 
with BrdU-containing DNA. 
Note: Plastic culture dishes containing 2x10^ cells each are subjected to 
white fluorescent light for 60 minutes. 
Figure 7-5. Macroscopic colonies in four randomly selected dishes 
approximately seven days after illumination with white light. 
Note: These clones, originating from cells surviving selection, are tested to 
determine if any are auxotrophic mutants. 
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