Fig. 4. rad9
1-231 mutants have similar phenotypes to chk1 mutants. Strains of the indicated genotypes were grown in liquid culture before a fivefold dilution series was prepared and spotted to YEPD plates. Strain numbers are in parenthesis. (A) rad91-231 mutants are not UV sensitive. Plates were untreated or exposed to 40 J/m2 UV before incubation for three days at 30°C. (B) yku70 rad91-231 cells are checkpoint arrest defective at restrictive temperatures. Growth was measured at the permissive temperature of 30°C and the restrictive temperature of 37°C. (C) Arrest kinetics of cdc13-1 mutants in synchronous cultures. Checkpoint mutations were combined with the cdc13-1 and cdc15-2 mutations. Cultures were arrested with 
-factor at 23°C then released into fresh media at 36°C. Accumulation of cells at mid-nuclear division (cdc13-1 arrest point) and late nuclear division (cdc15-2 arrest point) was measured by fluorescence microscopy at intervals of 20 minutes.