Figure 1.

Electron micrograph of sycamore protoplasts incubated in 40 nm polystyrene nano-spheres at 2 magnifications. Protoplasts were prepared from sycamore-cultured cells and incubated in a solution containing 50 mM sucrose and 4 × 10¹⁴ polystyrene nano-spheres per ml for 12 h. After incubation, protoplasts were fixed in 4% glutaraldehyde and 0.1 M cacodylate buffer before sample preparation for electron microscopy. (A and C) Electron micrographs of cells showing numerous polystyrene nano-spheres inside the vacuole. (B and D) Close-up of corresponding cells (A and C, respectively) at higher magnification. (E) Electron micrograph of a control sycamore protoplast incubated in the absence of polystyrene nano-spheres for 12 h. Note the homogeneous vacuolar interior as compared to those in (A–D). (F) Electron micrograph of a control polystyrene nano-spheres immobilized in agar. (G) Electron micrograph of a polystyrene bead inside a cytosolic structure other than the central vacuole likely representing the endosome.