Figure 6.

Negative stain electron micrographs from human GSS-A117V and Bv-Scr isolates. The P2 and P4 fractions from the GSS-A117V isolates (A) and Bv-Scr (B) as well as the corresponding SN2 fractions (after alcohol precipitation) were negatively stained with uranyl acetate. The P2 and P4 fractions from the GSS-A117V isolates (A) contained a layer of small amorphous particles that covered the carbon film surface (filled arrowheads on select particles). No amyloid fibrils or larger protein aggregates were observed, occasional lipid structures and amorphous structures were visualized (black arrows). The SN2 precipitate was composed of amorphous aggregates only (white arrows), which is typical for alcohol precipitates. In contrast, the P2 and P4 fractions from Bv-Scr (B) contained substantial quantities of amyloid fibrils (black dashed arrows), which tended to aggregate into larger clumps, partially obscuring their ultrastructure. The SN2 precipitate again showed only amorphous structures (white arrows) because of the alcohol treatment. Scale bars = 100 nm.