FIG 4.

Transmission electron micrographs of ultrathin sections of high-pressure-frozen, freeze-substituted, Lowicryl-embedded (A to C) or rehydrated and cryosectioned (D) K. stuttgartiensis cells incubated with antibodies against kustc0457/58. Thin sections were incubated with 1:150-diluted anti-kustc0457/58 (A and B), 1:50-diluted preimmune serum (C), or 1:100-diluted anti-kustc0457/58 (D). Gold particles were visible only inside the anammoxosome, preferentially located toward the inner side of the anammoxosome membrane. Incubation with preimmune serum led to the detection of a few gold particles throughout the cell. Electron-dense, iron-containing particles (16 to 25 nm; white arrowhead) were distinguished from gold labels (10 nm; black arrowhead) by size and appearance. Scale bars, 200 nm.