The actin cytoskeleton in 3-month-old tobacco mesophyll cells as visualized by plastin-GFP (green fluorescence). (A, B) Network of actin in dark-adapted cells. "Baskets" around chloroplasts marked with arrows and circular structures marked with arrowheads; yellow-red colour comes from autofluorescence of chloroplasts. (C) Reorganization of F-actin after 1 h of exposure to continuous wBL (0.4 Wm-2). Strands which spread across the cortical cytoplasm, frequently split into thinner filaments (marked with arrowheads). (c) Actin filaments forming baskets are better resolved after wBL. (D) Wide bands of F-actin (arrows) have a loose contact with chloroplasts after exposure to SBL (10 Wm-2, 20 min). (E) Effect of continuous wRL (0.24 Wm-2, 1 h) or (F) to SRL (6.7 Wm-2, 20 min) on the actin cytoskeleton. Scale bars, 10 μm. The cytoskeleton forms numerous small loops (B and D, arrowheads), most of them containing mitochondria. Insets b and d show magnified chloroplasts with mitochondria visible (orange/red colour) in the AC loops after staining with TMRE.