Distribution of Hbs and Rst is dynamic in the eye epithelium.

<p>The activity of a <i>hbs</i> reporter was assessed using an anti-lacZ antibody (A–B). Cone cells are marked (asterisks). A) The activity of the <i>hbs</i> reporter was detected in emerging PPCs at 18 h APF. The nucleus of a PPC precursor (arrow) was rising half way to the level of cone cell nuclei while the nucleus of the second PPC precursor was lagging behind (open arrowhead). B) The activity of the <i>hbs</i> reporter was detected in PPC precursors at 20 h APF. The nucleus of a PPC precursor (arrow) had arisen to the level of those of cone cells while the nucleus of the second PPC precursor was still below the plane (open arrowhead). C) <i>rst</i> was transcribed in IOCs (open arrowhead) at 18 h APF. <i>rst-Gal4</i> was used to drive expression of nuclear GFP(<i>rst>GFP</i>). The location for an ommatidium is indicated (asterisk). D–G″′) Distribution of Hbs and Rst is dynamic during 18–40 h APF. The Hbs channels (red) are shown in D–G and the Rst channels (green) in D′–G′. The merged views are shown on D″–G″. The enlarged views of boxed regions in D″–G″ are shown in D″′–G″′. For clarity, only Hbs channels are shown in D″′–G″′. Single IOCs (asterisks) and bristle groups (carets) are indicated. D) At 18 h APF, both Hbs and Rst were found at all borders surrounding PPC precursors including PPC-IOC borders (arrows) and PPC-cone borders (arrowheads). These proteins were also present at IOC-IOC borders (open arrowheads). E) At 20 h APF, PPCs fully enwrapped cone cells. Both Hbs and Rst were enriched at PPC-IOC (arrows), PPC-cone and PPC-PPC borders (arrowheads) while these proteins were slightly reduced at IOC-IOC borders (open arrowheads). F) At 27 h APF, both Hbs and Rst were enriched at PPC-IOC borders (arrows) while these proteins were reduced at PPC-PPC and PPC-cone borders (arrowheads). Hbs and Rst were diminished at IOC-IOC borders (open arrowheads). G) At 40 h APF, both Hbs and Rst proteins were enriched at IOC-PPC borders (arrows) while they were diminished at PPC-PPC and PPC-cone borders (arrowhead). Hbs and Rst were undetectable at IOC-IOC borders (open arrowheads). Scale bars, 10 µm.