Extended Data Figure 2. DSB formation appears normal in SPO11-flag and SPO11-PrA strains.
a, Southern blots probed for Chr III. High molecular weight chromosomal DNA was purified 6 hr after transfer to sporulation medium from meiotic rad50S cultures carrying the indicated SPO11 alleles (in spo11-yf the catalytic tyrosine 135 is mutated to phenylalanine), then separated on pulsed-field electrophoresis gels. Samples from a rad50S spo11-HA strain are shown for comparison; HA-tagged Spo11 has reduced DSB frequency. Each lane represents an independent culture (SPO11+ samples from the same cultures were run on both gels). P, parental-length DNA; W, wells. b, Quantification of blots in panel a and separate blots (not shown) probed for Chr VII or VIII. Break frequencies are percent of DNA in lane (mean ± SD of 3–4 cultures). Numbers in parentheses indicate values from each tagged strain relative to SPO11+ for the same chromosome. Relative DSB frequencies at the bottom are averages across the three chromosomes assayed.
