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. 2018 Oct 8;14(10):e1007680. doi: 10.1371/journal.pgen.1007680

Fig 3. De novo sperm crossover activity in the distal region.

Fig 3

(A) Sperm CO profiles for each of the two ePAR-carrying men analysed. A total of 158 recombinants were recovered from 76,800 sperm from man 53 using reciprocal crossover assays (i.e. Ab plus Ba COs, where AB and ab are the parental haplotypes) compared with 42 from a total of 92,000 sperm from man 20. Recombination activity expressed in cM/Mb along the assayed intervals is shown in the central graphs with the crossover activity of man 53 shown by the dark grey histogram and that of man 20 by the light grey histogram. The combined least-squares best-fit normal distribution for both men is shown by the black curve. The recovered CO structures together with their frequencies are shown above (man 53) and below (man 20) with heterozygous SNP locations represented by circles. SNPs marked with an asterisk were exploited for recombinant recovery (see Methods and S6 Table). The pink panel spans the interval in which male meiotic DSBs were previously mapped by DMC1-SSDS [19] and coincides with the peak CO activity determined from de novo sperm events in this study. (B) Transmission frequencies of SNP alleles into reciprocal COs with 95% credible intervals determined by Bayesian analysis. Transmission of the ‘strong’ allele (C or G) is shown for transition polymorphisms and transmission of the purine allele (A or G) is shown for the transversion polymorphisms. The upper panel shows the transmission data from man 53, the lower panel those for man 20. All markers with the exception of rs1970797 in man 53 were consistent with the expected 50:50 transmission of the two alleles into reciprocal events. This polymorphism lies 126 bp proximal to the predicted hotspot centre and 210 bp distal of the closest hotspot motif [73], as indicated at the top of the upper panel. CO asymmetry has previously been noted at hotspots that do not contain obvious matches to this motif, yet are nonetheless specifically activated by PRDM9 A [38,42]. Note that our failure to observe asymmetry for man 20 may simply be a consequence of the small number of COs detected for this donor.