Fig. 1

Hbn expression during Drosophila development. Laser confocal images of Drosophila embryonic, larval and adult brains. A-C Images of HRP (green) and Hbn (red) staining in three sections of an embryonic brain at stage 15 from dorsal to the ventral (brain commissure level). Major expression domains are indicated by arrowheads, including the medial region (red arrowheads), central region (white arrowheads), lateral region (yellow arrowheads), and brain commissure (blue arrowhead). D Ventral view showing Nrt staining in a right larval brain hemisphere (L3) to highlight the main structures. CB, central brain with type I cell lineages; ME, medulla; LA, lamina; LP, lobula plate. The border between the central brain region and the optic lobe region is indicated by a white arrowhead. E-I Dorsal to ventral sections of a right larval brain hemisphere stained with anti-Hbn (green) and anti-Nrt (red) antibodies. The largest expression domains are indicated: the dorsomedial domain (DM), dorsolateral domain (DL), the dorsal inner proliferation centre (dIPC), the medulla (ME), the neuroepithelium (NE), the lobula (LO), the lobula plate (LP) and the ventral central brain domain (white arrowhead). No expression is observed in the lamina (LA). Additional smaller domains are also indicated by white arrowheads. J-L Images of three different focal planes of the right part of an adult brain showing the expression of Hbn in green and Brp in red. J In the more anterior focal plane, Hbn expression is observed in the medulla (ME) and a discrete domain between VLP and SLP (yellow arrowhead). K In a more medial focal plane Hbn expression is also observed in the medulla (ME) (white arrowhead). L In the posterior focal plane, Hbn is expressed in the medulla (ME) (white arrowhead) and some cells in the central brain. Abbreviations: AL, antennal lobe; LO, lobula; PLP, posterior-lateral protocerebrum; SLP, superior-lateral protocerebrum; VLP, ventro-lateral protocerebrum. (Scale bars: A-C, 25 μm; D, 50 μm; E-I, 50 μm as in E; K-M, 50 μm as in K)