Figure 2
Extracellular Syns hamper axon guidance.
(a) Neurons cultured on a coverslip assembled upside down over a Dunn’s chamber with the outer well filled with 40 μM cyclic 8-br-cAMP that forms a gradient by diffusion. Neurons were imaged at 1 frame/min for 30 min, images are shown at 0 min and at 30 min from application of the gradient (grey bar on top). (b) Trajectory plots of growing axons exposed to a gradient of attractant cue during the 30 min of the experiment in ctrl, wt and A30P Syn-treated neurons at 2 DIV. The source of chemoattractant is at the top of the plots. The initial direction of the axon was aligned with the horizontal axis. (c) Quantitative evaluation of the percentage of axons turning toward the attraction gradient in neurons treated as in (b). Data from neurons of each experiment were pooled and statistical analysis was performed comparing the data from independent experiments. (d) Quantitative evaluation of axon elongation during 30 min in neurons treated with or without wt or A30P Syn. In (c, d) data are expressed as mean values ± SEM. In (c), ctrl, n = 30; wt Syn, n = 17; A30P Syn, n = 18, from 3 independent cultures. In d ctrl, n = 20; wt Syn, n = 14; A30P Syn, n = 12, from 3 independent cultures. Statistical significance was determined by one-way ANOVA followed by Dunnett’s test for multiple comparison, *P < 0.05; ***P < 0.001. (c) P = 0.0001, alpha value: 0.050:1.000; (d) P = 0.0424, alpha value: 0.050:0.450) Bar in a: 10 μm.
