Figure 1 Phenotypes of mutants in exc-1
, encoded by C46E1.3. (A) Diagram showing position of excretory canals (blue) and amphid sheaths (green) in wild-type C. elegans; lateral view (anterior on left, dorsal on top). Apical (luminal) surface of excretory canals is shown in red, lumen in white. Lumenconnects in the cell body (gray, containing nucleus), to the excretory duct cell (not shown). Canals extend both anteriorward and posteriorward from cellbody. (B-J) Micrographs of lateral views of canals. (B-D) Canal marked by stable cytoplasmic Pvha-1::gfp construct qpIs11 in wild-type animal (B) and in exc-1
) animals showing variable effects with mild (C) or severe (D) effects on tube diameter and length. Wide arrows indicate excretory cell body; hollow arrowheads indicate position of vulva at center of animal; narrow arrows indicate fluid-filled cysts. Bars, 100 um. (E and F) Micrographs of exc1(rh26
) mutant microinjected with rescuing amplified fragment of fosmid WRM0636cA10 containing the promoter and coding region of C46E1.3 DNA and containing the canal cytoplasmic GFP marker qpIs11. (E) Both anterior and posterior canals are visible on either side of the canal cell body. (F) Posterior canal extends full-length to the tip of the animal and is of normal diameter, indicated between two solid arrowheads. (G) Wild-type animal injected with dsRNA corresponding to the sixth exon of C46E1.3 phenocopies the exc-1
) canal, with large cysts (arrows) evident. (H) Injection of transcriptional construct containing 1.6 kb upstream of transcriptional start site linked to gfp shows expression in excretory canal cell (wide arrow) and amphid sheath cell, including cell body and amphid sheath (hollow arrows). (I and J) Injection of translational construct of exc-1
::gfp shows expression concentrated near the apical surface near the canal lumen, and shortens canal length, with normal-diameter folded lumen apparent at terminal end of posterior canal. J is the same as I, sharpened and contrast enhanced to show regions of strongest expression. In E-J, arrowheads show normal-diameter tubule; narrow arrows indicate fluid-filled cysts; hollow arrows indicate amphid sheaths. Bars, 10 um. (K-N) Position of EXC-1 relative to marked apical surface in young adult animal. K shows confocal green fluorescence from injected exc-1
::gfp; L is red fluorescence from injected erm-1
::mCherry in same section; and M is DIC (contrast enhanced) of same section, with apical edges of lumen marked in red. N shows average brightness of fluorescence along horizontal lines within area boxed in K-M, starting outside of canal on the dorsal side and continuing ventrally. Position of lumen derived from DIC image is labeled in graph.