vas RNA is uniform in the

syncitial blastoderm, but is degraded upon cellularization, including in the

germ cells. It is zygotically expressed in the germ cells at stage 11, and can be seen in the embryonic gonad at stage 13-14.

vas expression is observed in male germ cells.

vas expression is observed in female germ cells.

vasa protein is cytoplasmic within pole cells. In some cell types in ovaries and testes, vasa protein distribution is perinuclear.

germline cell

The vas protein is expressed in germ cells at the larva/pupa transition, 108 hrs AEL.

In stage 10 oocytes, vas protein, osk protein, and stau protein colocalize at the posterior pole. In early embryos, vas protein and osk protein localize to the polar granules but stau protein does not colocalize with them. It is present in a thin crescent apposed closely to the posterior cortex and disappears before the pole cell stage. A GFP-Vas fusion protein was used to determine the vas protein distribution.

vas protein is concentrated in the form of polar granules at the posterior pole in early embryos. A low level of staining is also seen throughout the embryo during cleavage stages. vas protein is also present in egg chambers. Protein expression in mutants of vas, stau, osk, tud, vls, and BicD were studied.

vasa protein is detected in larval and pupal ovaries in the oogonial cells and their precursors. It is abundant in the germaria of adult ovaries and is also abundant in the pronurse cell nuclei in early stages of oogenesis. vasa protein is transported to the oocyte starting in stage 8 and is concentrated at the posterior pole, although it is detectable at lower levels throughout the oocyte. vasa protein is also detected in males in the larval spermatogonial cells and in cyst cells of the adult testis. In early cleavage stage embryos, a shallow posterior-anterior gradient of vas protein is seen with the highest concentration at the posterior pole. Later the pole cells stain heavily and the pole cell and subsequent gonadal expression persists throughout embryogenesis. In ovaries lacking tud, vls, nos, and pum, vas protein localizes to the posterior pole of the oocyte normally but in ovaries lacking osk and stau, vas protein fails to distribute asymmetrically. BicC mutations affect vas protein distribution while BicD mutations do not. capu and spir abolish localization of vas protein to pole cells. vas protein is detected in ovaries of egl, mus301, qua, Bic-F, mr, Fs(2)Y12, and vss mutant females.

vas protein is located at the posterior pole of early embryos. This posterior localization is abolished in mutants of stau, vas, spir, capu, and osk. Posterior localization of vas protein is less striking in tud and vls mutants than in wild type embryos and indistinguishable from wild type in nos and pum mutants.

vas protein in both late-stage oocytes and in early embryos is localized to the posterior pole, and thus differs from the uniform distribution of vas transcript at the same stage. In addition to late-stage oocytes, the vas protein is found in germline stem cells and nurse cells of ovaries. In adult males, the vas protein is present in male germline stem cells during early spermatogenesis.