Figure 6.

Propagation of generation-3 fibrils to generation-6.A and B, region of 2D ¹³C solid-state DARR NMR spectra of generation-6 Aβ40-WT fibrils derived from the CAA/ad (A) and CAA/s (B) cases. The region of the spectrum exhibiting cross-peaks consistent with parallel, in-register β-sheet structure (blue box) and antiparallel β-sheet structure (red box) are shown. C and D, rows are shown through the diagonal resonances of 2-¹³C Ala30 at 48.6 ppm (red) and 3-¹³C Ala30 at 20.1 ppm (blue) of generation-6 Aβ40-WT fibrils derived from the CAA/ad (C) and CAA/s (D) cases. E–G, TEM images of generation-6 Aβ40-WT fibrils from the CAA/ad (E and G) and CAA/s (F) cases. The predominant morphology is twisted fibrils with crossing points of ∼100–200 nm. However, highly twisted fibrils with crossing points of <50 nm were also observed. In panel (G), arrows indicate representative crossing points with a spacing of <50 nm. Scale bars are 100 nm. H, Region of the 2D ¹³C DARR NMR spectrum of generation-6 Aβ40-WT fibrils labeled with ¹³C-ring Phe19 and U-¹³C Leu34 for the CAA/ad case. The ¹³C-ring Phe19 resonance falls along the diagonal in this region of the 2D NMR spectrum, while the other resonances correspond to cross-peaks between Leu34 and the Phe19 ring.