IFT transgene overexpression enhances the structure/morphology defects of tm2322 mutant cilia. (A) Fluorescence images of amphid/phasmid cilia in N2 and arl-13(tm2322) animals expressing gfp-tagged IFT transgenes show that IFT proteins localize normally to ciliary axonemes (ax) and accumulate normally at ciliary bases (asterisks) in tm2322 worms. In tm2322 mutants overexpressing che-13::gfp, osm-6::gfp, and bbs-7/8::gfp, amphid/phasmid cilia morphologies are more severely defective than other transgenic strains. Enhanced defects include missing DS staining (open arrowhead), axonemes that are less tightly bunched and highly disorganized (closed arrowheads; open arrow), and increased frequency of large axonemal bulges (closed arrows). (B) arl-13 animals overexpressing osm-3::gfp, che-2::gfp, che-11::gfp, and che-13::mCherry(low expression level) display similar levels of DiI incorporation to nontransgenic controls (arrowheads indicate dye uptake in cell bodies). However, tm2322 mutants overexpressing che-13::gfp, osm-6::gfp, bbs-7::gfp, dyf-1::gfp, and che-13::mCherry(high expression level) are SynDyf, failing to take dye. Merged DIC–fluorescence images (head) after a DiI uptake assay are shown. Bars: (A) 2 µm; (B) 10 µm.