Fig. 5. Immunolocalization of modified histones during meiosis. Merged photos of anti-histone antibody (green) and meiotic chromosomes (red) are shown. Assignment of meiotic stages in ask1-1 meiocytes is based on chromosome morphology and the stage of the surrounding tapetal cells. (a) Immunolocalization of dimethyl-histone H3 lysine 4 in wild-type meiocytes. (A) interphase; (B) leptotene/zygotene transition; (C) pachytene. (D) metaphase I. Arrow indicates weak signal at pachytene. ask1-1 meiocytes exhibited similar labeling patterns (data not shown). (b) Immunolocalization of acetylated histone 3 (positions 9 and 14) in wild-type (A-C,G-I) and ask1-1 (D-F,J-L) meiocytes. (A,D) Interphase; (B,E) leptotene; (C,F) zygotene; (G,J) pachytene; (H,K) metaphase I; (I,L) telophase I. (c) Immunolocalization of dimethyl-histone 3 lysine 9 in wild-type (A-C) and ask1-1 (D-F) meiocytes. (A,D) Interphase/early leptotene; (B,E) zygotene; (C,F) pachytene. Note the nucleolus in ask1-1 is also stained with DAPI (red) at later stages, suggesting the persistent association of chromatin with nucleolus in the mutant. Nu, nucleolus. Bars, 10 µm.