Figure 2.

anti-ACT-5 specifically labels the apical intestine. (a–d) Wild-type embryos costained with purified anti-ACT-5 antibodies (a and b) and C4, a pan-reactive anti-actin mAb (c and d). Images represent single confocal optical sections from the middle third (a and c) and top third (b and d) of the same threefold embryo. Arrows indicate the posterior (a and c) and anterior (b and d) of the intestine, where robust anti-ACT-5 label, but very little C4 staining is present (a vs. c); arrowheads point to a single longitudinal body wall muscle quadrant, which is not detected with anti-ACT-5 but readily labeled with C4 (b vs. d). Bar, 5 μm (a–d). (e and f) Wild-type L1 animals stained with anti-ACT-5, in white (e) or red (f); DAPI-stained nuclei are shown in blue (f). ACT-5 label decorates the lumenal surface of the intestine, showing as a tube along most of the length of this L1 animal. Images in e and f are projections of serial image slices that encompass approximately one-half the volume of an intestine and derive from the central portion of the intestine; this processing reveals the unlabeled lumenal area at the center of the intestine. Bar, 10 μm (e and f).