Fig. 9

Cholinergic neuronal ageing correlates best with the decline in motility. A Schematic showing the experimental outline. The ∆body length was determined for strains expressing ChR2 in muscle, cholinergic neurons and GABAergic neurons at several time intervals. At the same time, the movement capacity, represented as bends per 30 s in liquid, was also measured. B The decline in thrashing capacity in liquid of worms expressing ChR2 in cholinergic or GABAergic neurons. n = 15, two-way ANOVA (Age: p < 0.001, interaction and neuron type: n.s.). The experiment was triplicated, one representative experiment is shown (see D for the averages of the other two experiments). C The normalized ∆body length (elongation for GABA, contraction for muscle and cholinergic neurons) at different ages as measured by the midline approach. Every point represents the mean of an experiment with > 10 biological replicates each. Fitted lines represent a general linear model with 2nd-order polynomial fit. All points within one experiment were normalized by the intra-experimental average at D1 within each strain. D The average decline in thrashing ability over time. Every point represents the mean of an experiment with > 15 biological replicates each. All points were normalized by the inter-experimental average at D1 within each strain. This sets the average bends per 30 s to exactly 1.0 at D1. Fitted lines represent a general linear model with 2nd-order polynomial fit. E The correlation between the ∆body length and ∆movement capacity (normalized to the changes and capacity at D1 intra-experimentally). Fitted lines represent simple linear regression without restrictions (both slopes deviate significantly from zero: p < 0.001). The black line corresponds to a relation of x = y, in which the decline in movement is equal to the decline in ∆body length. F The ∆eccentricity (eccentricity before illumination minus eccentricity during illumination) at different ages after optogenetic stimulation. Each individual point represents the mean of n > 15 worms. Student’s t test: n.s. All experiments were replicated three times, all replicates are shown. The transparent zones around the fitted lines represent the confidence interval (95%). *: p ≤ 0.05, **: p ≤ 0.01, ***: p ≤ 0.001