Fig. 3. FISH of telomere, centromere (CEN=pAL1) and BAC probes to wild-type Arabidopsis nuclei. (A,B) Combined BrdU labelling and FISH following a 1 hour BrdU pulse +3 hours to show clustered telomere signals (A) and dispersed and extended CEN signals (B). BrdU is detected by anti-BrdU antibody labeled with FITC (green); both telomere and CEN signals are red. (C-I) Dual FISH of telomere (red) and CEN (green) probes to Arabidopsis PMC. (C) Nucleolus-associated clustering of telomeres and dispersal of CENs seen in meiotic interphase; the white dotted circle indicates the approximate boundary of the nucleolus (D). (D-I) Progressive changes in telomere and CEN signal numbers and distributions during meiotic prophase I; (D) early leptotene showing 15 clustered telomere signals and ten dispersed CEN signals, arrows here and elsewhere indicate the chromosome 1 CEN-associated telomere signals; (E,F) dual (E) and triple (F) filter images of the same leptotene nucleus showing ten dispersed CEN signals and eight semi-dispersed telomere signals, indicating colocalisation of some telomeres; (G) zygotene, showing nine telomere signals (two colocalised) and four CEN signals resulting from stage-specific chromatin clumping; (H) pachytene, showing nine telomere signals (two colocalised) and five CEN signals; (I) early diplotene showing early stage of desynapsis; note that telomeres are still paired at this stage. (J-L) Dual FISH with telomere (red) and BAC (green) probes to demonstrate that telomere pairing involves homologous chromosomes; (J) meiotic interphase showing clustered unpaired telomeres and BACs; (K,L) leptotenes, showing paired telomeres and BACs T9J23 (K) and F19K16 (L). All nuclei are counterstained with DAPI. Bar, 10 µm.