Figure 1.

H2A.V is required for proper chromosome condensation and segregation. (A) DAPI stained colchicine-treated (Aa–d) mitotic cells from control (Aa), H2A.V⁸¹⁰ (Ab) and H2A.V⁸¹⁰/Df(3R)TI-P (Ac–d) mutant brains. H2A.V mutant metaphases exhibit chromosomes with poorly condensed centromeric chromatin (arrows in Ab), overcondensed chromosomes (Ac), or chromosomes with precocious sister chromatid separation (Ad). (B) Quantification of mitotic defects in H2AV mutants and in H2A.V mutants also bearing a H2A.V transgene with a C-terminal truncation. See text for further details. N = Normal cells; D = Cells with poorly condensed chromosomes; DH = cells with chromosomes exhibiting decondensation at the pericentric region; OP = Cells showing either overcondensed chromosomes or precocious sister chromatid separation; B = Cells with chromosome breaks. (C) Mitotic Index (MI) and Frequency of Anaphases (AF) in WT, H2A.V⁸¹⁰, H2A.V⁸¹⁰ [H2A.V⁺] and H2A.V⁸¹⁰ [H2A.V^ΔCT] larval brain cells (*P < 0.01, t Student's Test). (D) Mitotic spindles of wild type (Da,b) and H2A.V mutant (Dc,d) stained for tubulin (green), Spd2 (red) and DAPI. (Da) Wild type metaphase; (Db) wild type anaphase; (Dc) a H2A.V mutant cell with scattered chromosomes; (Dd) a rare example of H2A.V mutant cell with a monopolar spindle. Bar = 5 μm. E) Quantification of spindle defects in WT, H2A.V⁸¹⁰ and H2A.V⁸¹⁰ [H2A.V^ΔCT]. BPM = prometaphases/metaphases with normal bipolar spindles; BPA = ana/telophases with normal bipolar spindles; BPS = cells with dispersed chromosomes and normal bipolar spindles; MPM = metaphases and ana/telophases with monopolar spindles.