Inducing the CRISPR-Cas9 expression in solid medium
For continuous induction on solid medium, transformants carrying the Cas9 plasmid are grown overnight in liquid SC-Rep medium. The optical density at 600nm of the culture is determined, and aliquots are plated on SC-Ind plates as well as on repressive SC-Rep medium. Colonies are grown, counted and plates are compared in order to estimate the survival rate (number of colonies obtained on induction medium divided by number of colonies obtained on repression medium, expressed as a percentage). Induction plates are replicated on YDP-Rep, grown and examined for colony color; both sectored and completely red colonies being scored together. The rate of red colonies is expressed as a percentage of the total number of colonies. In experiments that were used to compute the survival and ade- rates, the minimum number of colonies counted on SC-Rep is 50, and usually around 500. All experiments were performed on at least two independent transformants and repeated at least twice per transformant. Controls without the gRNA (transformation with pCFYF) and controls without plasmid (with uracil added to media) were prepared and analyzed in the same way. Standard deviations are calculated and shown as error bars in graphs.