K veleta ccd camera

5 µl of Aβ42 fibrils was drop casted on formvar/carbon-coated 400 mesh copper grids and washed twice with 5 µl MQ water after incubation on grid for 10 min. Samples were stained with 5 µl of 1% uranyl formate and excess stained was wiped with Whatman filter paper after 3 min. Samples were allowed to air dry at room temperature. Imaging was performed using a FEI Tecnai 12 Spirit BioTWIN microscope, operated at 100 kV with 2 x 2 k Veleta CCD camera (Olympus Soft Imaging Solutions, GmbH, Münster, Germany). For each sample, 10-15 images were obtained randomly at magnification between 20,000x–60,000x. ImageJ (1.52 K, Wayne Rasband, NIH, USA) software was used for analysis of fibril diameters, where 100 different fibrils were analyzed. Statistical tests were performed using an unpaired two-tailed T-test calculated with GraphPad Prism 9, where four asterisks (****) refer to p < 0.0001.

For immunostaining, baculovirus sample solution was adsorbed on each 200-mesh copper grid with carbon-coated plastic film (Nisshin EM, Tokyo, Japan) and then incubated with an anti-DAF (human CD55) mouse monoclonal Ab (Millipore, Temecula, CA) in phosphate-buffered saline. After washing with PBS, each grid was incubated with a 5 nm colloidal gold-conjugated goat anti-mouse IgG Ab (BBI solutions, Cardiff, UK) in PBS. After washing again, each grid was negatively stained with 1% uranyl acetate solution for 10 s. To test the effect of the serum on the baculovirus samples, the baculovirus sample solution was mixed with heat-inactivated or non-heat-inactivated serum and then incubated for 1 h at 37 °C. The morphology of each baculovirus sample was observed on a JEM-1230 (JEOL, Tokyo, Japan) with an 80 kV acceleration voltage, and images with taken using a 2 k × 2 k Veleta CCD camera (Olympus Soft Imaging Solutions, Lakewood, CO).