Figure 6
CLSEM to study adhesion to, and invasion of MDCK cells by Listeria monocytogenes. Shown is a timeline of morphometric changes of the host cell membrane during invasion of L. monocytogenes (red) in polarized Lifeact-eGFP MDCK cells (green). (i) Listeria adhered to microvilli on MDCK from time point 1:52 p.i., no increase of F-actin signal was visible. This matches lack of morphological changes in SEM. (ii) At 2:50 p.i., a small F-actin accumulation was visible (white arrowhead). In SEM, slight increase of membrane material appears at one side of bacterium (black arrowhead). (iii) At 5:40 p.i., fluorescence signals for F-actin and Listeria are both visible in SDCM (white arrowhead). The ultrastructure in SEM modality indicates that a small membrane protrusion had engulfed the bacterium (black arrowhead). Time stamp, min:sec. Scale bars, 1 µm (SEM), 5 µm (SDCM).
