Figure 3. MEC-1 and MEC-5 Localization. (A) Expression of GFP from a
mec-1 promoter. The six touch neuron cell bodies are indicated. The left side is seen on the upper worm, the right side on the lower worm. Scale bars here and in panels (B)-(E), 50 μm; scale bars in subsequent panels, 10 μm. (B-E) &
sup2;-galactosidase expression from
mec-1::lacZ fusions. Fusions with MEC-1(1-22) were used in (B) and (C); fusions with MEC-1(1-45) were used in (D) and (E). The fusions in the second panel of each pair contained an artificial transmembrane domain. (F-H) MEC-1::GFP fluorescence in (F) the cell bodies of PLM, PLN, and ALN neurons showing perinuclear expression (presumably in the endoplasmic reticulum), (G) a PLM touch neuron, and (H) an ALM touch neuron. Puncta (white dots) are seen above a more uniform fluorescence. Fluorescence is never seen in the processes of the non-touch receptor neurons. (I) GFP fluorescence from a
mec-1 promoter fusion in an ALM touch neuron. (J) MEC-1::GFP fluorescence on a PVM ventral process. The uniform fluorescence seen on the lateral processes is not found. Lines perpendicular to the PVM process are the annuli, which we find autofluoresce in the GFP and YFP channels of the confocal microscope. The confocal image has been collapsed from a Z series to show the annuli. (K) GFP fluorescence from a
mec-1 promoter fusion in the ventral process of a PVM touch neuron. (L-P) MEC-5::GFP is not made by the touch neurons (Du et al., 1996) but adheres to them and muscle. (L) MEC-5::GFP fluorescence is both uniform and punctate on the lateral process of an ALM neuron. (M) Magnified view of another ALM process showing the double nature of the uniform fluorescence. Puncta are indicated by dots. (N) The uniform fluorescence is less obvious on the ALM process in the nose. (O) MEC-5::GFP fluorescence on the process of the ventral cord touch neuron PVM. The puncta vary in intensity. (P) MEC-5::GFP binds to apparent dense bodies (solid arrows) and muscle boundaries (dashed arrows) in muscle.