THE EFFECTS OF DIFFERENT SONICATION METHODS ON ALPHA-SYNUCLEIN PRE-FORMED FIBRILS

Alpha-synuclein (α-syn) aggregation is associated with neuronal death and the pathological hallmark of Parkinson's disease (PD). The α-syn preformed fibril model (α-syn-PFFs), reflects α-syn aggregation and is currently used in PD studies. To pass through the cell membrane, long fibrils should be fragmented by sonication. In our study, the effects of temperature, pulse modifications and/or device type on the sonication of α-syn-PFFs were investigated. Sonication was performed ultrasonic bath and in laminar-flow cabinet with probe sonicator. Dilutions were made from 5 µg/µl α-syn-PFFs stock in sterile-filtered dH2O to a final concentration and volume of 0.1 µg/µl and 200µl, respectively. Sonication was performed in an ultrasonic bath containing water at 10°C for 1 hour. All probe sonications were performed at 30% amplitude for 1 minute and 20 repetitions. The effect of temperature on sonication has been evaluated by performing sonication at room temperature (RT), in ice and in ice surrounded by dry ice. Also, the effects of pulse duration on sonication were evaluated using pulse durations of 1second(sec) on/1sec off, 3sec on/3sec off and 5sec on/5sec off. Furthermore, by waiting one minute between each sonication cycle, the heat released by the probe was prevented from affecting the fibrillar structure. The particle size was measured in triplicate by dynamic light scattering method. For transmission electron microscopy, formvar/carbon-coated grids were run through ddH2O-sonicated fibril-uranyl acetate solutions and kept dry until examined. Due to the variation in breakage of long α-syn fibrils, the effect of different parameters on sonication was investigated. In comparison of pulse durations, 5sec on/5sec off application produced shorter fibrils. Comparing the temperature interventions, lowering the temperature decreased the fibril size at 1sec on/1sec off settings but increased it at 3sec on/3sec off and 5sec on/5sec off. However, the shortest fibrils were obtained by sonication for 5sec on/5sec off at RT