||Fig. 4 Rab11 mRNA and protein expression during development. (A) Whole mount in situ hybridization was performed for Rab11 on albino embryos at 1-cell (i), 4-cell (ii), blastula (iii), gastrula (iv) and neurula stages (v). At all stages, a diffuse signal (purple) was visible throughout the embryo with the strongest signal localized in the animal pole. Sense probes show little signal at all stages examined (vi, data not shown). Red arrows indicate signal, blue arrow on blastula stage embryo indicates
areas with lower signal due to contraction of the hollowembryo during fixation; this is an artifact. bp = blastopore, nf = neural folds. (B) Immunohistochemical analysis was performed for Rab11 protein on 100 lm sections collected from embryos at 1 cell (i and ii), 4-cell (iii and iv), blastula (v), gastrula (vi) and neurula (vii). At 1-cell, Rab11 protein is localized to the animal
hemisphere, with the strongest expression near the cleavage furrow (i) and no other visible biases (ii). At 4-cell Rab11
remains localized to the animal hemisphere (iii) and is relatively symmetrical along the LR and dorsalentral axes (iv). A
small portion of embryos showed slight asymmetries along the LR axis at 4-cell, but these were not consistently biased (data
not shown). Rab11 is highly localized within cells of blastula (v) and gastrula stage embryos (vi). This strong expression likely
corresponds to the perinuclear region of the cell (see v', vi'). In neurula stages, Rab11 is visible in the neural folds and
notochord, and a diffuse signal is also visible throughout the endoderm (vii). Green arrows indicate positive signal.