Figure 3. Latrophilin Signaling in the Pharynx. (A)
lat-1(
ok379) has a pharyngeal phenotype. The traces show an electropharyngeogram (EPG) [9] recorded from a wild-type and
lat-1(
ok379) animal. Each recording represents a single muscle pump, with the first upward deflection corresponding to contraction and the last downward deflection corresponding to relaxation. The small potentials that appear during the pump have been associated with neuronal activity in the pharyngeal neuron M3 [38].(B) The role of LAT-1 in the inhibitory effect of emodepside on the pharynx. Assays for pharyngeal activity were performed as for Figure 2A. The
lat-1 control group for RNAi was
rrf-3(
pk1426)[36] fed on bacteria transformed with vectors for dsRNA but in the absence of IPTG so that the expression of dsRNA was not induced. The graphs show concentration-response curves for the effect of emodepside on pharyngeal pumping in wild-type with an IC50 of 4.1 nM (95% confidence limits 1.2 to 14.7 nM);
lat-1(
ok379) with an IC50 of 53 nM (95% confidence limits 26 to 109 nM);
rrf-3(
pk1426) (dsRNA control) with an IC50 of 2.9 nM (95% confidence limits 0.3 to 10 nM); and
lat-1 RNAi with an IC50 of 70 nM (95% confidence limits 22 to 219 nM). Each point is the mean ± S.E.M. of 'n' determinations. *p < 0.05 and **p < 0.01 with respect to control. (C) The expression pattern of
lat-1 was determined using a
lat-1::DsRed2 reporter construct for expression of DsRed2 fused to the N-terminal domain (51 amino acids) of LAT-1. Expression was only observed in the anterior region of the animal.(C) is a fluorescence image from the anterior region of L3 stage larval animals.(D) A fluorescence image from L3 superimposed on a bright field background. Note the distinctive labeling in the pharyngeal muscle (m).(E) and (F) show images from the anterior of adult animals. (F) is a dissected pharynx showing a neuronal pattern of expression. One neuron is marked 'n' as an example. Confocal images were obtained on a Zeiss Axioskop 2 LSM 510 Meta laser scanning microscope consisting of a Z-series of 24 sections, total depth 22.7 μm.