Fig. 7. MAX-2 is required for the axon guidance effects induced by ectopic expression of UNC-5 in the anterior touch cell receptor neurons. (A-C) DIC images of adult animals after fixation and staining for the presence of lacZ. In all images, dorsal is up and anterior is to the left. Black arrowheads mark the dorsal cord, white arrowheads mark touch receptor cell bodies and black arrows mark touch receptor cell axons. For clarity not all cell bodies and axons present are marked in each image. Animals [evIs41[Pmec7::lacZ,Pmec7::unc-5];pag-1(ls2)] that ectopically express UNC-5 and lacZ under the control of the mec-7 promoter have the anterior touch receptor cell axons (ALMs and AVM) guided to the dorsal cord (A). (B,C) In a max-2 background, the guidance effects from ectopic expression of UNC-5 are partially suppressed. The image in B is two superimposed images from different focal planes of the same animal. Occasionally we observed ventral migration of the AVM axon in a max-2 background, as shown in C. We never observed this in the ectopic UNC-5 strain alone. (D) A graphical representation of the quantification of ALM and AVM guidance in the two populations. The numbers (n) of animals used for each experiment are shown; bars represent the standard error. The asterisk denotes a P-value less than 0.001 (Student's t-test). Scale bar: 10 µm.