Fig. 4

Interaction of ThT dye with α-synuclein aggregates derived from patients with PD or MSA is dependent on the RT-QuIC reaction buffer used. a Aggregation curves of α-synuclein in the presence of brain homogenates from a representative PD patient, a representative MSA patient, and a control subject, amplified with buffer 1 (50 mM Gly, pH 4, 250 mM NaClO₄). Data are mean ± SEM of representative subjects measured in quadruplicate. b–d Area under the curve values (b), maximum ThT fluorescence values (c), and T50 (d) for PD (n = 15), MSA (n = 15), supranuclear progressive palsy (n = 5) and controls (n = 5). Each dot represents an individual biological sample measured in quadruplicate. e At the ultrastructural level, the MSA-derived RT-QuIC fibrils were thicker and more twisted than the PD-derived fibrils, as determined by electron microscopy. f–i Same as that for a–d, except that aggregation was performed in buffer 2 (40 mM PB, pH 8, 350 mM Na₃Citrate). j At the ultrastructural level, the MSA-derived RT-QuIC fibrils were thicker and more twisted than the PD-derived fibrils, as determined by electron microscopy. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 by one-way analysis of variance (ANOVA) followed by Tukey’s multiple comparison test. Scale bar, 25 nm