Fig. 2: Seeding and spreading following PFF injection into mouse OB.

a Differentiation of PSER129-positive pathology from endogenous PSER129 pool required pretreatment of tissues with proteinase K (PK). OB sections from a single PFF-injected mouse were stained for PSER129, with or without PK pretreatment. High magnification images show PSER129 reactivity in the granule cell layer (GL), mitral cell layer (ML), and external plexiform layer (EPL). Scale bar = 50 µm. b Pathological αsyn distribution across the neuroaxis 6 months following bilateral injections of PFFs into 4-month-old WT and homozygous GBA1 D409V KI mice. Tissues were treated with PK prior to immunostaining PSER129 using tyramide signal amplification (TSA). Sections counterstained with methyl green, making nuclei appear light green-blue. PSER129 was detected using the chromogen nickel-enhanced DAB, which appears black. Representative whole-section scans show the tissue distribution of PSER129 positive αsyn pathology throughout the brain. c Representative images of OB and piriform cortex showing PSER129 staining that was quantified. Red dotted box superimposed on whole tissue scans highlights the approximate areas that the high magnification image was taken. Scale bar = 100 µm. d Quantification of PK-PSER129 reactivity in the main OB and piriform cortex of WT and GBA1 D490V KI mice treated with PFFs. e Quantification of PK-PSER129 reactivity in the main OB and piriform cortex of mice treated with αsyn PFF polymorphs amplified from PD and GBA-PD clinical brain specimens. *Two-Way ANOVA F (1, 40) = 7.235, P < 0.05. For d, PBS_WT n = 14, PFF_WT n = 11, PBS_ GBA1D490V KI n = 10, PFF_ GBA1D490V KI n = 9. For e, HOM1 n = 9, HOM2 n = 5, iPD1 n = 10, HET1 n = 10, HET2 n = 9, HET3 n = 9, PBS n = 8.Error bars denote the standard error of the mean.