Fig. 4

Growth of ‘Ca. Berkiella cookevillensis’ in non-phagocytic HeLa cells. a Confocal micrographs of FISH staining with 6-FAM-conjugated probe and helper probes targeting the 16S rRNA of ‘Ca. B. cookevillensis’ confirms the infectivity of ‘Ca. B. cookevillensis’ for HeLa human epithelial-like cells. Bar, 5 μm. b TEM images of bacteria appearing to be within the nucleus (n) of a HeLa cell. The left image (bar, 2 μm) shows the location of the nuclear envelope (white arrow). Mitochondria (m) are visible in the cytoplasm. The bacteria appear surrounded by electron-translucent space within a vacuole. The vacuolar membrane (white triangle) is visible in the enlarged image (right) with the vacuole surrounded by loose euchromatin. Dividing cells can also be seen in the image (bar, 500 nm)