Fig. 3. Olfactory axon trajectories are severely disrupted in dock and Pak mutants. ALs of animals expressing GFP under the control of various Gal4 drivers were either observed with fluorescence microscopy (I,K,L) or stained with anti-GFP (green) and nc82 mAb (red) and examined by confocal microscopy (A,C-E,G,H). (B,F,J) Interpretive drawings of confocal images (A,B₁) In the wild type, upon entering the AL, SG18.1-Gal4 expressing axons radiate over its surface in characteristic tracks in search of their target glomeruli. These pathways are bilaterally symmetric and invariant from one lobe to another. (B₂ ,C) In the dock^P1/dock^P1 and (D) Pak⁴/Pak⁶ mutants, however, SG18.1-Gal4 axons take circuitous paths in the nerve layer creating a homogenous mat. Some axons project to dorsal brain regions (arrowheads) in dock^P1 mutants. (E,F₁) In the wild type, Or47a axons take direct paths, with little sidetracking, from the entry point to their target, DM3. (F₂,G) However, in dock^P1/dock^P1 and (H) Pak⁴/Pak⁶ mutants, Or47a axons make chaotic and meandering projections, terminating in numerous ectopic glomeruli. (I,J₁) In the wild type, Or47b axons terminate immediately on VA1lm upon entering the AL. A distinct fascicle, containing contralateral axons, connects the glomerulus with the commissure. (J₂,K) In dock^P1/dock^P1 and (L) Pak⁶/Pak¹¹ mutants, the VA1lm glomerulus is severely mis-shapen and contralaterally projecting axons enter and exit the glomerulus over its entire surface. Asterisks in A,E,I indicate the antennal nerve entry points at the anterior lateral region of the AL. Scale bar: 25 µm.

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