Localization of Aust in primary spermatocytes. (A) Primary spermatocytes fixed and stained with antibodies to α-tubulin (green), Aust (red), and with DAPI (blue). Upon entry into meiosis I, Aust accumulates on condensing chromosomes, concentrating at specific chromosomal locations by metaphase. In anaphase, Aust remains associated with chromosomes but additionally accumulates at the cell equator. By telophase, Aust staining is apparent at the central spindle midzone. (B) Metaphase I spermatocytes stained for DmINCENP (green), Aust (red), and DNA (blue). DmINCENP and Aust colocalize at kinetochores. Bars, 10 μm.