Figure 5

P. aeruginosa biofilm fragments elevated the Aβ pathology in adult zebrafish. ThT assay of Aβ (50 × 10⁻⁶m, 37 °C) in the presence or absence of biofilm fragments (5 × 10⁻⁶m, with respect to protein contents) (n = 3). Like FapCS, biofilm fragments significantly accelerated Aβ fibrillization. B) TEM images of Aβ fibrillized with biofilm fragments. The fragments appeared to be adsorbed onto Aβ fibrils. C) Movement trajectories and D) quantification of behavioral pathology, at 4 d postinjection, when Aβ was injected together with biofilm fragments (n = 3 per group and 3 groups per sample). Biofilm fragments enhanced Aβ toxicity and significantly (**, p < 0.005) suppressed the swimming behavior of adult zebrafish. E) Movement trajectory and F) quantification of the cognitive behavior of the fish in arena 1 versus arena 2 of the swimming tank (n = 3 per group and 3 groups per sample). Fish injected with biofilm fragments + Aβ presented deteriorated cognitive memory function at 4 d postinjection while biofilm fragments alone did not induce any behavioral toxicity. At 4 days postinjection, adult fish brains were subjected to IHC. H) Aβ deposition and I) quantification of Aβ deposition as green fluorescence of antibody labeling (n = 3), J) synaptophysin positive cells, K) quantification of antibody labeling of synaptophysin positive cells (n = 3), L) TUNEL assay and M) quantification of cell death in TUNEL assay (n = 3). Like FapCS, biofilm fragments enhanced Aβ deposition, accelerated the depletion of synaptophysin positive neurons and induced cell death in the brain of adult zebrafish.