Fig. 1.

GABA_B receptors contribute to GABA photoevoked body elongation and affect swimming cycles in cholinergic motor neurons. A and B: channelrhodopsin-2 (ChR2), expressed in GABAergic motor neurons (MNs) (transgene zxIs3; Liewald et al. 2008), was photostimulated to evoke body elongation. Animals of the indicated genotypes were filmed, and the body length during 2 s before and from 0.5 to 2 s during the photostimulation was measured, normalized, and averaged. For an alternative method of analysis, see Fig. 2. Blue light intensities of 1.6 (A) and 0.16 mW/mm² (B) were used. See text for list of strains used. C: swimming cycles in M9 buffer were compared in wild-type and gbb-2(tm1165) mutant animals in thrashing assays and could be rescued by expression of GBB-2(A484V; V572A) selectively in cholinergic MNs. Values are means ± SE; n = no. of animals assayed. Statistically significant differences (*P < 0.05; **P < 0.01; ***P < 0.001; 1-way ANOVA) were assessed with respect to body length before blue light stimulation (A and B) or to the wild-type level (C).