The Drosophila olfactory system, the lola gene, and Lola expression. (a) Schematic representation of the Drosophila antennal lobe. Olfactory receptor neuron (ORN) axons project to stereotyped glomeruli in the antennal lobe (AL). The anterodorsal (ad), lateral (l) and ventral (v) lineages of Gal4-GH146 positive PNs send dendrites to specific glomeruli in the AL and axons to specific regions in the mushroom body (MB) calyx and lateral horn (LH). (b) Schematic representation of the lola gene. lola is a complex genetic locus consisting of at least 20 isoforms generated by both cis- and trans-splicing of an amino-terminal BTB domain-containing common region to unique carboxy-terminal exons, most of which contain Zn fingers. Individual isoforms are labeled in accordance with previous nomenclature . Mutations are marked by asterisks and isoforms with UAS transgenes are listed. (c-g) Time course of Lola expression using an antibody generated against the common region (amino acids 19–467). Lola is expressed in all neurons adjacent to the AL at all stages of development, shown at 24 h after larval hatching (ALH), 72 h ALH, 0 h after puparium formation (APF), 18 h APF and adult. Lola is also expressed in the neuroblast (arrow in c). In this and all subsequent figures, non-overlapping fluoresence channels are pseudocolored for ease of viewing: anti-CD8::GFP in green, anti-Lola in magenta. Dashed vertical line marks the midline. Antenna lobe (AL) outlined with thin dashed line in (g). (h, i) Specificity of anti-Lola antibody. Lateral lola-/- (ore76) MARCM clone stained with anti-pan Lola. In (h), the white outline denotes entire MARCM clone determined by loss of Lola staining. The yellow outline denotes boundary of GH146 positive cells based on GFP expression. Loss of Lola staining in GH146 cells can be seen clearly in the magenta (Lola) only channel (h2). In (i), a DL1 single-cell lola-/- MARCM clone shows a loss of Lola staining in the magenta channel (i2). The arrow marks the same cell in (i1) and (i2). Scale 10 μm. Green, anti-CD8::GFP; magenta, anti-Lola; blue, DAPI.