Ning chromosomes (Parent) was determined by subtracting the quantity of the NCO band in HindIII VDE digests from the amount of the Parent NCO band in HindIII digests.(B) Noncumulative VDEDSB frequencies, measured as fraction of total lane signal, excluding loading controls, in HindIII digests.(C) Crossover (average of CO and CO) and noncrossover frequencies, measured in HindIIIVDE digests.Solid linesrecombinants from cells expressing VDE; dashed linesSpoinitiated crossovers from vde strains, measured in HindIIIVDE digests and therefore corresponding to VDEresistant solutions (see also Figure figure supplement C).Values will be the typical of two independent experiments; error bars represent variety.Representative Southern blots are shown in Figure and Figure figure supplement C..eLife.The following figure supplement is readily available for figure Figure supplement .of VDEDSBs are repaired..eLife.Medhi et al.eLife ;e..eLife.ofResearch articleGenes and ChromosomesFigure .Unique resolvasedependence of crossover formation at the two insert loci.(A) Crossover Drosophilin B SDS frequencies (average of CO and CO) measured as in Figure C from HIS insertcontaining mutants lacking MutLg (mlh), structureselective nucleases (mmsmd yen slx) or both resolvase activities (mlh mmsmd yen slx).(B) Crossover frequencies in URA insertcontaining strains, measured as in panel A.Values are the typical of two independent experiments; error bars represent variety.(C) Final crossover levels (typical of and hr values for two independent experiments), expressed as percent of wild type.Note that, in mlh mutants, crossovers in HIS inserts are reduced by almost , while crossovers in URA inserts are reduced by much less than PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/21492929 .(D) Final noncrossover levels, calculated as in C, expressed as % of wild form.Representative Southern blots are in Figure figure supplement ..eLife.The following figure supplements are accessible for figure Figure supplement .VDEDSB and NCO frequencies in resolvase mutants..eLife.Figure supplement .Southern blots of HindIII and HindIIIVDE digests of DNA from HIS insertcontaining strains (top) and from URA insertcontaning strains (bottom)..eLife.Medhi et al.eLife ;e..eLife.ofResearch articleGenes and Chromosomesconsistent with earlier findings, that cutting each sister chromatids at a DSB website is connected using a reduced proportion of COs amongst repair products (Malkova et al).MutLg tends to make distinctive contributions to VDEinitiated CO formation at the two insert lociWhile VDEinitiated recombination occurred at similar levels in inserts located at HIS and at URA, we observed a marked difference among the two loci, when it comes to the resolvasedependence of CO formation (Figure).In the HIS locus, COs were lowered in mlhD mutants, which lack MutLg, by relative to wild sort.In mmsmd yenD slxD mutants, which lack the three structure selective nucleases active for the duration of both meiosis and also the mitotic cell cycle (SSNs, triple mutants hereafter referred to as ssn mutants), COs had been lowered by , and by in mlh ssn mutants.Thus, like Spoinitiated COs, VDEinitiated COs in inserts at HIS are primarily MutLgdependent, and much less dependent on SSNs.In contrast, COs in inserts situated at URA were decreased by only in mlh, by in ssn mutants, and by in mlh ssn mutants, in order that the final amount of residual COs was precisely the same as at HIS.Therefore, SSNs make a substantially higher contribution to VDEinitiated CO formation at URA than does MutLg, and MutLg’s contribution becomes substantial only within the absence of.