(a) Seeded amyloid growth monitored by Thioflavin T fluorescence in reactions seeded by fibril samples sonicated for different amounts of time. For clarity, one replicate curve (out of three) for each seed sample (red: 15 s, orange: 30 s, yellow: 60 s, green: 120 s, cyan 240 s, blue: 480 s, and purple: 960 s of sonication) is show together with one unseeded growth curve (black). (b) Dependency of seeding potential on particle concentration. Mean initial slope of seeded growth is plotted against the particle concentrations of the seed samples calculated from their length distribution (blue cross). The red line denotes best-fit linear model with the slope of 8.5·108 h−1M−1. Yellow cross denotes seeding efficiency of an independent sample sonicated for 60 s, left yellow cross shows seeding efficiency at addition of 1% seeds, and upper right yellow cross shows seeding efficiency at addition of 2% seeds predicted to have the same seeding efficiency as the sample sonicated for 960 s represented by the right most blue cross.