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. 2012 Feb 8;32(6):1920–1931. doi: 10.1523/JNEUROSCI.2064-11.2012

Figure 3.

Figure 3.

SER-7 activates isthmus peristalsis by activating G12α signaling in M4. A, Schematic of the G12α signaling pathway in C. elegans. B, C, Expression of constitutively gpa-12(Q205L) (B) or constitutively active rho-1(G14V) (C) in cholinergic neurons was sufficient to activate isthmus peristalsis but not pharyngeal pumping in the absence of serotonin. C, The F25N mutation completely suppressed the increase in isthmus peristalsis rate caused by the constitutively active rho-1(G14V) mutation. D, The dgk-1(sy428) null mutation increased both feeding rates in response to serotonin. E, F, The G12α and Gsα signaling pathways act redundantly to activate isthmus peristalsis in response to serotonin. The gsa-1(pk75); gpa-12(pk322) double-null mutant (F), but not the gpa-12(pk322) single-null mutant (E), decreased isthmus peristalsis in response to serotonin. G, dgk-1(sy428) fully restored isthmus peristalsis rate in the transgenic animals expressing rho-1(F25NG14V) in cholinergic neurons to the level of the transgenics expressing rho-1(G14V) in response to serotonin. H, Expression of constitutively active gpa-12(Q205L) in M4 (and occasionally in M2) significantly increased the isthmus peristalsis rate in gsa-1(ce81);ser-7(tm1325) in response to serotonin. I, Expression of constitutively active rho-1(G14V) in M4 (and occasionally in M2) fully restored isthmus peristalsis in gsa-1(ce81);ser-7(tm1325) in response to serotonin. The number of animals tested (n ≥ 3 independent assays per each group) is shown in parentheses. ***p < 0.001; *p < 0.05; n.s., not significant (p > 0.05); unpaired t test (two-tailed test) was used for comparison of pharyngeal pumping rates, and the difference is marked in green; isthmus peristalsis rates were compared as described in Materials and Methods, and the level of significance is indicated by asterisks in pink; the number of animals tested (n ≥ 3 independent assays per each group) is shown in parentheses. For the comparisons with the transgenics expressing rescue constructs, the transgenic animals expressing only co-injection marker(s) were used as controls.