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Fig. 2
Sycp1 length, numbers of engaged telomeres, and numbers of co-alignments in male zebrafish meiosis I. A: Average Sycp3 length vs. average Sycp1 length. Each circle represents the average of all measurements in one nucleus (n = 30 nuclei). B: Total Sycp3 length vs. total Sycp1 length in the same cells shown in A. Stages of meiosis are defined by total length of Sycp1: leptotene (L, Sycp1 = 0 μm; yellow); leptotene to zygotene transition (L/EZ, Sycp1 = 1–10 μm; blue); early to mid-zygotene (EZ/MZ, Sycp1 = 10–50 μm; pink); mid to late zygotene (MZ/LZ, Sycp1 = 50–100 μm; purple); late zygotene (LZ, Sycp1 > 100 μm; cyan). C: Numbers of engaged telomeres per cell, where one engaged telomere end is an Sycp3 line with its telomere associated with a potentially non-homologous telomere end. Each point represents one cell. The data was pooled from two experiments done on different days (set 1, orange circles; set 2, green diamonds). The highest numbers of engaged telomere ends were observed in L and L/EZ stages after which point there was a significant decrease in engaged telomere ends in the EZ/MZ category, p < 0.0001 (unpaired t test with Welch’s correction), however, some number of engaged ends were maintained throughout prophase I. D: Examples of funnel and pinch co-alignment configurations. In the funnel configuration the co-alignment is directly adjacent to the telomeres; in the pinch configuration the co-alignment is not directly adjacent to the telomeres. White arrows point to the co-aligned regions. The blue arrow points to a pinch configuration where SC has already started to form (not counted as co-aligned). E: Total numbers of co-alignments in different stage cells of meiosis I prophase. Each point represents one cell. F: Numbers of co-alignments (0–5) in individual cells in WT (n = 24) and spo11 -/- (n = 32) males. The LZ class was excluded from the WT representation as at this stage synapsis has typically initiated at the majority of telomere ends. spo11 -/- cells, where synapsis is mostly abolished, were assessed for co-alignment if they appeared to have Sycp3 lines of similar lengths to the leptotene and zygotene classes of WT.