Figure 6

Transmission electron micrographs of cells of Magnetospirillum magnetotacticum, after Prussian blue (PB) treatment of free-floating cells. (A) The magnetosome chains in the cells are not labelled by PB and remain in place (lower right). The actual PB reaction products are the micrometer-sized box-like structures in the upper left corner of the image, with the electron dense cube in the middle representing an insoluble PB crystal, as determined from its diffraction pattern. (B) At higher magnification, the magnetosome chains are still present, but the magnetosome particles appear to have lost their distinct crystal edges and rather have etching pits, which suggests partial dissolution, attributable to the acid treatment (as part of the PB protocol). It can be shown that the visible chains still consist of iron oxide using energy-disperse X-ray scans (see Fig S2). Scale bar 200 nm (A) and 50 nm (B).