Chromatin Immunoprecipitation (ChIP) using GeneTex Affinity Purified Mre11 (S. cerevisiae) antibody (GTX12159). A yeast strain containing the HO endonuclease gene controlled by a galactose-inducible promoter (uninduced 0 m lanes) was shifted into galactose containing medium (induced 60 m lanes). After 1 hour of induction cells were cross-linked with formaldehyde followed by preparation of sheared chromatin. Chromatin was immunoprecipitated with the antibody at the stated dilutions. Immunocomplexes were captured using polyacrylamide bead linked secondary antibodies. The resultant immunoprecipitate was probed by multiplex PCR, using primers 20 bp from the MAT locus double strand break (lower arrow) and 67 kb from the break (upper band, control locus). PCR products were displayed on a polyacrylamide gel, stained with SyBR GreenR (Invitrogen), and detected using a Fuji scanning fluorometer.