Figure 3. The I2 Neurons Secrete Glutamate to Rapidly Block Muscle Contraction(A) Mutants of
eat-4(
ky5) VGLUT were defective in the acute response to light. n = 60 worms.(B) Expression of genomic
eat-4 (njEx378) completely rescued the defective acute response of
eat-4 mutants. n = 20.(C) Top: Nomarski differential interference contrast optics (DIC) image of an L4 worm head. Bottom: expression pattern of
eat-4 as indicated by a transgenecarrying njEx378[
eat-4prom::
eat-4::gfp]. Expression was observed in I2, but not in the NSM neuron. The scale bar represents 7 mm.(D) I2-specific expression of the wild-type
eat-4 gene (
flp-15prom::
eat-4 cDNA::gfp) in
eat-4 mutants partially restored the acute response to light. Three independenteat-4 strains carrying transgenes showed a quantitative improvement in the acute response (see E and F). The trace from strain no. 1 is shown. n = 55.(E and F) Quantifications of acute response latency (E) and acute response amplitude (F) are shown. # indicates independently integrated transgenic strains.n = 55-60.(G)
eat-4(
ky5);
lite-1(
ce314) double mutants were nearly completely defective in the pumping response to light. The
lite-1(
ce314) trace includes data previouslypublished [16]. n = 80.(H) I2-specific expression of the wild-type
eat-4 gene in
eat-4;
lite-1 double mutants partially restored the acute pumping response to light. n = 40.(I) Quantification of acute response latency.(J) Quantification of acute response amplitude.(K)
avr-15(
ad1051) glutamate-gated chloride channel (GluCl) mutants had a delayed pumping response to light. n = 60.(L) Pharyngeal muscle (PM)-specific expression of the wild-type
avr-15 gene (
myo-2prom::
avr-15A cDNA) in
avr-15 mutants restored normal acute responselatency. n = 60.(M) Quantification of acute response latency.Error bars and shading around traces indicate SEM. ***p < 0.001; **p < 0.001; t test compared to wild-type,
lite-1, or indicated strain.See also Figures S3-S5.