Fig. 3. Pros26.4 protein expression. (A-B") Pros26.4 protein expression during oogenesis is shown in red. The nuclei are shown in green by use of a histone H2A-GFP reporter line (A,A" and B, B"). (A,A') In early follicles, Pros26.4 protein is detected uniformly in the cytoplasm of all cell types, the somatic follicle cells (small arrow) as well as the oocyte and nurse cells which both belong to the germ line. In stage 9 (right follicle) and following, conspicuous accumulation of Pros26.4 protein is observed in the germinal vesicle (white arrow). Earlier follicles, for example the one to the left (stage 8), do not reveal this accumulation. Moreover, nurse-cell nuclei are largely devoid of the protein (open arrowheads). (B) A close-up of the germinal vesicle (white arrow) in a stage-10 follicle shows lower levels of Pros26.4 protein. Nurse-cell nuclei (open arrowhead) and follicle-cell nuclei (small open arrow) are largely devoid of Pros26.4 protein. (C-E) Protein expression in embryos is uniform and can be detected in the cytoplasm and also in nuclei starting from blastoderm stage (C, stage 5, arrow indicates pole cells), throughout germ band extension (D, stage 11) and retraction, and also during dorsal closure (E, stage 14). At this later stage, the protein is enriched in the neuromeres of the ventral chord (open arrowheads) and the midgut (white arrow). Nuclear accumulation is mostly apparent in the nuclei of the amnio-serosa (small arrow).