Fig. 5: Efficient SC and CO formation require IHO1-HORMAD1 interaction.
From: Seeding the meiotic DNA break machinery and initiating recombination on chromosome axes
A-C, F, G Quantifications of SC morphology relative to axis development (A), I-IV non-exclusive SC defect types (B), axis-length ranks of partially (blue) or completely (red) unsynapsed autosomes (C), MLH1 focus numbers on synapsed autosomes (F) or total MLH1 numbers (G) in spermatocytes of adult mice. Leptotene to early pachytene cells (identified by a lack of histone H1t) (A), pachytene cells (B, C), or both fully synapsed and asynaptic (F) or only fully synapsed (G) late pachytene cells were examined. Pools of two experiments are shown (one mouse represented each genotype in each experiment). Bars are means (A, B, F) or medians (C, G), error bars are standard deviation (A), n=numbers of spermatocytes. Likelihood ratio test (A, B, F) or two-tailed Mann Whitney U-Test (C, G), ns=P > 0.05, **=P < 0.01, ***=P < 0.001, ****=P < 0.0001. Exact P values: (A), (dotty axis) P = 0.5195, (short axis) P = 0.08376, (long axis) P = 0.00735, (full axis) P < 2.2e-16, (B), Iho1+/+ vs. Iho1C7Δ/C7Δ (early pachytene) P = 1.1e-9, (mid-pachytene) P = 1.97e-14, (late-pachytene) P < 2.2e-16, Iho1C7Δ/C7Δ early vs. mid-pachytene P = 6.43e-7, Iho1C7Δ/C7Δ mid- vs. late pachytene P = 1.7e-5, (C), early vs. mid- P = 6.26e-3, early vs. late P = 8.53e-8, mid- vs. late P = 0.634, (F), P = 0.0001898, (G) P = 5.51e-5. D, E Immunostaining in nuclear spread spermatocytes of adult mice. Asterisks, sex chromosomes. D Insets are enlarged under respective panels. Arrowheads mark partially or fully unsynapsed autosomes, arrow marks non-homologous SC. Miniaturized images (left bottom corners) show histone H1t, a marker of mid and post-mid pachytene stages (intermediate or high levels, respectively). Roman numbers refer to SC defect types as described in B. E Iho1C7Δ/C7Δ cells where either all chromosomes have MLH1 (cell 1) or a synapsed autosome lacks MLH1 (cell 2, arrowhead). D, E Bars, 10 µm. See also related Supplementary Fig. 9. Source data are provided as a Source Data file.
