Fig. 1. XPB subcellular distribution in early Drosophila embryogenesis. XPB was localized using a polyclonal antibody. XPB signal is in red; DNA is in green after Sytox green staining. (a) Syncytial blastoderm embryo after the first nuclear division (two nuclei, stage 2). (b) Syncytial blastoderm embryo at stage 8; the nucleus starts to move towards the embryo periphery and XPB remains cytoplasmic. (c,c') A similar embryo at stage 8 of development, but only the surface staining shown. Note that XPB surrounds the nucleus in cytoplasmic domains or energids. (d) Syncytial blastoderm embryo at stage 10. XPB enters into the nuclei, which are now located in the embryo periphery. (e) Cellular blastoderm embryo. At this stage, most of XPB signal is located inside the nucleus. (f) Gastrulated embryo. XPB is preferentially nuclear in the interphase nuclei, but excluded from mitotic chromosomes. (g) Amplification of the periphery of a stage 10 embryo. The arrows indicate XPB signal inside the nucleus. (h) Amplification of a cellular blastoderm embryo. (i) Amplification of a gastrulated embryo. The arrow indicates a group of mitotic chromosomes. Bar, 100 µm.