Figure 8. Three promoters govern the transcription of the C. elegans
pkc-2 gene in vivo. Lines of transgenic C. elegans carrying the
pkc21A:lacZ,
pkc21B:lacZ, and
pkc21C:lacZ expression plasmids were produced as described under Experimental Procedures. The histochemical stain for β-galactosidase (Experimental Procedures) generates an insoluble precipitate in the nuclei of cells transcribing the
pkc-2 gene. Panel A shows that the
pkc21C promoter is active in neurons in the anterior of the nematode and four sensory neurons in the rectal ganglion. The tip of the head of the L1 larva is at the upper right in the micrograph; the tail is at the lower left. Panel B reveals that the
pkc21A promoter drives gene transcription in body wall muscle cells (immediately below the tip of the head, upper right), as well as pharyngeal neurons, intestinal cells, and sensory neurons of the tail ganglia (preceding from the tip of the head toward the tail in the lower left portion of the micrograph) in an L1 larval nematode. The positions of the various cell types are explicitly labeled in panel C A portion of a wild type (unstained) adult C. elegans appears at the right side of panel B Cells exhibiting
pkc21B promoter activity are evident in panel C The positions of muscle cells (M), sensory neurons (N) that are immediately anterior and posterior to the nerve ring, cells comprising the anterior end of the intestine (I) and sensory neurons of the tail ganglia (T) are indicated. Cells with lightly stained nuclei that lie between the I and T regions constitute the central and lower segments of the intestine. The orientation of the L1 larva is the same as the animals shown in panels A and B Panel D shows the mid-section of an adult C. elegans hermaphrodite. The
pkc21B promoter activates gene transcription in subsets of symmetrically disposed somatic cells in the gonad (including the spermatheca). A single, heavily-stained extra-gonadal cell is also observed.