Gels showing filament growth after seeding in 0.1% TFA/40% acetonitrile (a) or in 50 mM sodium phosphate at pH 7.0 (b). Lane 1, mock-seeded; lane 2, seeding with amorphous aggregates; lane 3, seeding with GdmCl-denatured filaments; lane 4, seeding with filaments; lane 5, seeds alone directly loaded. (c) CD spectra of 5 μM Sup35pN in 50 mM sodium phosphate at pH 7.0: (•) mock-seeded, (○) seeded with filaments; the solid line corresponds to the spectrum of the added seeds.