Ultrastructural Analysis of Cells

For scanning electron microscopy (SEM), cells were processed as published [10 (link)]. For transmission electron microscopy (TEM), samples were fixed in 2% PFA/2.5% glutaraldehyde for 1 h, post-fixed in cacodylate buffer/OsO4 for 1 h, and afterwards washed in cacodylate buffer. After dehydration, samples were infiltrated (propylene oxide and TAAB embedding resin, pure TAAB embedding resin) for 3 h, placed in TAAB embedding resin (2x 90 min), transferred into embedding molds, and polymerized (72 h, 60 °C). Sections were stained with lead citrate and platinum blue (International Bio-Analytical Industries, Inc., Boca Raton, FL, USA), and investigated at 120 kV with a Tecnai G 2 FEI microscope (FEI, Eindhoven, Netherlands) equipped with a Gatan ultrascan 1000 CCD camera.