Fig. 1.

SARK tau is mainly fibrillar, while HMW tau is mainly oligomeric. a Schematic of the experimental workflow to extract tau oligomers [17] (HMW Tau) and tau fibrils [42] (SARK tau) from the cortical gray matter of eight AD cases of Braak V–VI. b Total tau WB (DAKO) of SARK and HMW tau samples after incubation with increasing concentrations of proteinase K. c Quantification of the WB signal intensity after proteinase K treatment. Log-transformed data were plotted and the slopes compared. Linear regression testing for the equality of slopes, **p < 0.01. d Representative negative stain EM images of non-sonicated samples from AD case #2399 used for in vivo injections. HMW tau samples present mainly as amorphous material and a few PHFs (white arrows), while PHFs are more abundant in the SARK tau samples. Scale bar = 200 nm and 100 nm for inserts. MW molecular weight