The Cell Cycle Timing of Centromeric Chromatin Assembly in Drosophila Meiosis Is Distinct from Mitosis Yet Requires CAL1 and CENP-C
(A) Fixed imaging of GFP-CAL1 expression/localization in prophase I in larval testes. GFP-CAL1 is localized at centromeres and in the nucleolus in stage S3 and S4 nuclei, but is reduced/delocalized from centromeres by stage S5 and almost undetectable by stage M1a (late prophase I). Colocalization of GFP-CAL1 (green) and CID (red) signals at centromeres are shown in enlarged windows. Outlines of nuclei are circled in white. Scale bar: 10 µM. (B) Fixed cell analysis of CENP-C localization in larval testes. Larval testes were fixed and stained with anti-CENP-C antibody (red), anti-CID antibody (green), and DAPI (gray). CENP-C is present at centromeres at all stages of meiosis from prophase I to telophase II (shown, stages S1, M1a, M4, M7–M9, M10–M11) but is gradually lost from centromeres beginning at T1, coinciding with the time of CID assembly (see Figure 4). CENP-C is absent from centromeres in later stage T4–T5+ spermatids (see Figure S4). Scale bar: 5 µM, S1–M4; 1 µm, M7–M9–T5+.