Figure 4

Immunolocalization of DAE in the larval midgut. A) Four distinct domains of DAE antibody-labeled cells in larval midgut: anterior cells (AC) upstream of the copper cell domain (CC), large flat cells (LFC) immediately downstream of the CC domain, and 2-3 posterior cells (PC) downstream of the LFC (Pr = proventriculus). The higher magnification views (bar = 10 um) show continuous labeling of the basal membrane of adjacent cells in the AC region (vs. interstitial cells (I) that alternate with copper cells downstream). LFCs were usually visible on only one side of the epithelial tube, downstream of the last interstitial cell. B) DAE staining in the copper cell region revealed a pattern of labeled interstitial cells (I) separated by unlabeled copper cells. C) The copper cells stained with anti-α spectrin antibody appeared as lozenge shapes with relatively bright staining of the basolateral region (merged in D). Higher magnification views of the α spectrin (E) and DAE (F) staining patterns emphasize their lack of overlap. Alpha spectrin was most conspicuous in the basolateral zone of contact between copper cells and interstitial cells and in the banana-shaped apical invagination of copper cells. In contrast, DAE was most conspicuous within the basal cytoplasm of interstitial cells and extended apically in a gradient. G&H) High magnification views of the anterior cells stained for α spectrin (G) or DAE (H) reveals their overlapping distribution in the basal membrane region, but not in the lateral region of cell-cell contact (Bar = 10 um).