Centromeres of chromosome II and III become associated in the mitotic region, whereas X-chromosome centromeres are always paired.

<p>Fusome (α-spectrin, green) and DNA (DAPI, blue). (A, B) Projection of Z-sections obtained by DV microscopy of a wild-type germarium stained for the chromosome III centromere (dodeca probe, red), fusome, and DNA. (A) GSC showing 2 dodeca foci separated by a distance >0,7 µm. (B) 4 nuclei of a 8-cell cyst showing foci separated by a distance <0,7 µm. Nuclei with * show one focus, thus centromeres are paired, nuclei with one + display two foci separated by a distance ≤0,7 µm thus they are considered paired and nuclei with ++ display two foci separated by a distance >0,7 µm and are thus considered unpaired. Scale bars represent 2 µm. (C) Developmental changes in the percentage of paired chromosome III centromeres for each cell stage in region 1 using the dodeca probe. The number of cells analyzed is indicated under each stage. * p≤0.05, ** p≤0.005, *** p≤0.0005 (khi2 test comparing CB with 4cc, 2cc with 8cc and 4cc with 16cc). (D, E) Projection of Z-sections obtained by DV microscopy of a wild-type germarium stained for the chromosome II centromere (AACAC probe, red), fusome, and DNA. (D) GSC showing 2 AACAC foci separated by a distance >0,7 µm. (E) 5 nuclei of a 8-cell cyst showing foci separated by a distance <0,7 µm. Nuclei with * show one foci, thus centromeres are paired, nuclei with one + display two foci separated by a distance ≤0,7 µm thus they are considered paired and nuclei with ++ display two foci separated by a distance >0,7 µm and are thus considered unpaired. Scale bars represent 2 µm. (F) Developmental changes in the percentage of paired chromosome II centromeres for each cell stage in region 1 using the AACAC probe. The number of cells analyzed is indicated under each stage. * p≤0.05, ** p≤0.005, *** p≤0.0005 (khi2 test comparing CB with 4cc, 2cc with 8cc and 4cc with 16cc). (G, H) Projection of Z-sections obtained by DV microscopy of a wild-type germarium stained for the chromosome X centromere (359 probe, red), fusome, and DNA. (G) GSC showing one 359 focus. (H) 2 nuclei of an 8-cell cyst showing paired foci. Nuclei with * show one focus, thus centromeres are paired. Scale bars represent 2 µm. (I) Developmental changes in the percentage of paired X-chromosome centromeres for each cell stage in region 1 using the 359 probe. The number of cells analyzed is indicated under each stage.