FIG. 1.

The rad50S mutant is temperature sensitive for meiotic spore viability and defective for meiotic DSB repair and Rec12^Spo11 removal. (a) Meiotic spore viability relative to that of the WT in different strains at 25°C and 34°C. Error bars show standard deviations, and values are averages for three independent experiments. (b) Pulsed-field gel electrophoresis of a synchronized meiotic pat1⁺ rad50S culture at 25°C and 34°C. The bands labeled I, II, and III correspond to the intact chromosomes, and the smears labeled DSB correspond to broken DNA fragments. (c) Meiotic progression of the time course presented in panel b, expressed as numbers of cells that have completed meiosis I at different time points. (d) Slot blot showing the presence of covalently bound Rec12^Spo11 on the DNA 6 h after meiotic induction at 34°C. At time point 0, no Rec12^Spo11 signals were visible (data not shown). The arrow indicates where the top and bottom fractions of the CsCl gradient were loaded. The bulk of the DNA was found in fractions 5, 6, and 7, which showed the strongest Rec12^Spo11 signals for rad50 mutants.