Fig. 3. Localisation of VHA55::GFP in Drosophila tissues. The VHA55::GFP fusion was driven ubiquitously using a heat-shock-GAL4 driver, and distribution in tissues monitored by fluorescence microscopy. (A) Salivary gland, showing prominent apical brush border, intercellular boundaries, perinuclear region and reticular network throughout the cell. (B) Higher-power view, showing reticular network clearly. (C) Anterior midgut: only the cuprophilic (`goblet') cells are labelled. (D) Hindgut: fluorescence appears in a broad region of the hindgut, and a ring around the anterior rectum, but the ion-transporting rectal pads (right) are conspicuously unstained. (E) Ovaries, showing localised labelling of nurse cells and immature oocytes. (F) Testes, with regional staining of the ejaculatory bulb. (G) In situ hybridisation to adult tubule with Rhodamine-labelled probe for vha55. This confirms localisation of the transcript to principal cells: a stellate cell (identifiable by its smaller nucleus) is conspicuously unstained. (Nuclei are labelled blue with DAPI.)