Fig. 1

Fixed and fresh frozen tissue exhibit similar levels of seeding activity. a Transduction of aggregated tau into biosensor cells induces aggregation of endogenously expressed tauRD(P301S)-YFP fusion proteins. b Flow cytometry of tau biosensor cells can detects tau seeding based on FRET from aggregation of tauRD(P301S)-CFP and tauRD(P301S)-YFP fusion proteins. Note the population of cells that shift to the FRET-positive gate. c AT8 phospho-tau pathology is apparent in aged PS19 mice, whereas WT mice show no tau pathology. d Tau seeding activity is similar between fixed and fresh frozen tissue sections collected from aged PS19 mice. No significant difference was detected between fixed and fresh tissue at each concentration tested. Seeding is not detected in aged mice that express α-synuclein (A53T) [12]. Integrated FRET density is calculated as (Percent FRET-positive cells)*(median fluorescence intensity of positive cells). This value is normalized to a negative control sample. See Additional file 1: Figure S1a for an additional comparison of fixed versus fresh frozen tissue seeding, and Additional file 1: Figure S1b for seeding of fixed tissue embedded in PEG or paraffin. Error bars = S.E.M