Fig. 2: MRE11 fosters DSB number control.

a Genome-average S1-seq and Exo7/T-seq at hotspots in 5 wk old Mre11-cKO animals. Bottom-strand reads were flipped and combined with top-strand reads, averaged, and smoothed (151-bp Hann window; average of two biological replicates). S1-seq in 14.5-dpp wild type is shown on the same scale (average of three biological replicates). b S1-seq signal for Mre11-cKO (n = 2) and wild type (n = 10 for juvenile, 1 for adult). Each point is the area under the genome-average curve (as in panel a) from –1500 to +2500 bp relative to the hotspot center for an individual replicate. The P value is from a Student’s t test (two-sided). c Left, ATM activation by MRE11 and subsequent negative feedback regulation of SPO11. Right, absence of resection and increase in SPO11 double cuts in the absence of MRE11. d Offset top- and bottom-strand reads at hotspot centers in Mre11-cKO, consistent with double cutting. The plot shows the smoothed genome-average strand-specific profile close to hotspot centers (51-bp Hann window) with the SPO11-oligo profile for comparison. e Increased SPO11-oligo complexes with altered electrophoretic mobility in Mre11-cKO. The autoradiograph shows SPO11-oligo complexes immunoprecipitated from testis extracts from 5–6 wk old mice, radiolabeled with terminal transferase and [α-³²P]-dCTP, and separated by SDS-PAGE. The signal intensity of the region above the non-specific band, normalized to wild type, is indicated below. Asterisk: non-specific labeling. f SPO11 oligo lengths in Mre11-cKO. SPO11 oligos were purified from two mice of each genotype by immunoprecipitation and protease digestion, then radiolabeled with terminal transferase and [α-³²P]-GTP and separated by denaturing urea PAGE. Note that SPO11 oligos appear slightly larger than their true lengths because of nucleotide(s) added by terminal transferase and residual amino acid(s) not removed by protease. Both samples were run on the same gel, but the intensity of the Mre11-cKO signal was increased approximately threefold to facilitate comparison. Asterisks: non-specific species; nt: markers in nucleotides. Lane traces (background-subtracted and normalized to the total lane signal) are shown to the right. Expected migration positions of species arising from MRE11-dependent (canonical) resection and from SPO11 double cutting are indicated. Source data are provided as a Source data file.