Figure 1. Phylogenetic conservation and tissue expression pattern of C. elegans
kqt-1,
kqt-2, and
kqt-3 genes. A, phylogenetic tree of the KCNQ-KQT gene family. Three C. elegans KQT genes are shown with five human KCNQ genes. Two conserved subfamilies are apparent: KQT-3 groups with its human ortholog KCNQ1, whereas KQT-1 groups with KCNQ2-5. KQT-2 forms an outlying group. Branch length corresponds to sequence divergence (horizontal axis shows relative divergence). Clustal W parameters: gap penalty, 10; gap length penalty, 0.2; delay divergent seqs (%), 30; protein weight matrix, Gonnet series. C. elegans
kqt-1,
kqt-2, and
kqt-3 expression visualized with GFP translational gene fusions. B, prominent expression of
kqt-1::GFP in pharyngeal muscle cells. C, expression of
kqt-2::GFP exclusively in intestinal cells. D, expression of
kqt-3::GFP in the anterior-most pair of intestinal cells. Strongest intestinal expression is observed in anterior and posterior cells. E, expression of
kqt-1::GFP in tail mechanosensory neurons (PLM). Additional expression of
kqt-1::GFP is found in anterior mechanosensory neuron ALM (not shown). F, expression of
kqt-3::GFP in amphid chemosensory neurons ADL, AWB, and ASH in the head, identified by double labeling with DiI. Additional
kqt-3::GFP expression is observed in ASI less consistently, and in AWC. Image pseudocolored for GFP (green), DiI (red), and double-labeled GFP/DiI (yellow); cell bodies are outlined for clarity.
kqt-3::GFP expression is also observed in mechanosensory neuron PLM, and phasmid chemosensory neurons PHA and PHB in the tail (not shown). G-I, low magnification views of
kqt-1::GFP (G),
kqt-2::GFP (H), and
kqt-3::GFP (I) expression throughout the entire worms. GFP constructs were COOH-terminal translational fusions from genomic subclones (see Experimental Procedures). Scale bars: 20 μm (B-F) and 100 μm (G-I).