Figure 5.

Positional sister-chromatid alignment and/or separation at the lac O insertion sites in 4C leaf nuclei of A. thaliana line EL702C. (A) Scheme of chromosome 3 of line EL702C showing the lac O insertion sites (green) and the flanking regions MGL6 (red) and F18C1 (blue). (B) Selected images of nuclei after FISH with lac O, MGL6, and F18C1 with schematic interpretations below. (B₁) Separation of homologous chromosomes but alignment of sister chromatids of both homologs. (B₂) Allelic pairing and sister-chromatid alignment of both homologs. (B₃) Ectopic pairing within one homolog and sister-chromatid alignment concerning both homologs. (B₄) Allelic and ectopic pairing and sister-chromatid alignment of both homologs. (B₅) Ectopic pairing and sister-chromatid separation at one insertion site on both homologs (unambiguous as to separation). (B₆) Either allelic and ectopic pairing between both loci of both homologs and sister-chromatid separation at the distal locus of one homolog or allelic pairing between the proximal loci of both homologs, additional ectopic pairing involving one homolog, and sister-chromatid alignment of both homologs (ambiguous situation as to sister-chromatid separation; see text). Bars, 3 μm.