Actin filament mesh exhibits increasingly severe bundling gaps in exc-9, exc-1, and exc-5 mutants. (a) Scheme of summation of fluorescence through Z-stack serial pictures through half the depth (nearest to hypodermis and microscope objective) of canals and cysts to show filament morphology of LifeAct-labeled filaments at the canal apical surface. (b–f’’) All animals express cytoplasmic CFP under an integrated canal-specific promoter and an overexpressing construct of fluorescent actin label (LifeAct) under the same promoter. Left column: cytoplasmic fluorescence; center column, actin filament mesh; right column, merge. (b–d) Wild-type background (b); homozygous sma-1(ru18) background (c); and homozygous exc-9(n2669) background (d); arrows indicate a distinct thickly bundled actin filament, while arrowheads indicate a less distinct actin bundle. (e) Homozygous exc-1(rh26) background. (f) Homozygous exc-5(rh232) background. All scale bars, 5 µm. n ≥ 20 for all samples.