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Fig. 1 | BMC Microbiology

Fig. 1

From: Infection and nuclear interaction in mammalian cells by ‘Candidatus Berkiella cookevillensis’, a novel bacterium isolated from amoebae

Fig. 1

Growth of ‘Ca. Berkiella cookevillensis’ in Acanthamoeba polyphaga. A. polyphaga was infected for 48 h with ‘Ca. B. cookevillensis’ at an MOI of 1. a Intracellular bacteria were detected using confocal microscopy with helper and 6-FAM-labeled FISH probes specific for the 16S rRNA of the bacterium (green). DAPI staining was used to visualize the amoebal nucleus but also stains the bacteria (blue). Large numbers of bacteria are co-localized with nuclei of amoebae by 48 h p.i. Bars, 10 μm. b TEMs showing the growth of ‘Ca. B. cookevillensis’ following infection for 24 and 48 h in A. polyphaga at an MOI of 1. At 24 h, small numbers of bacteria are visible within the double-membraned (white arrow) nucleus (n). The euchromatin of the nucleoplasm appears more electron-lucent than the cytoplasm. Mitochondria (m) are visible in the cytoplasm. The bacteria are most often seen within an electron-translucent space surrounded by a darkened, single membrane (white triangle). More than one bacteria-containing vacuole often appears within a nucleus. On occasion, no electron-translucent space or membrane is visualized around the bacteria, as for the bacterium at 24 h (indicated by >). By 48 h, increased numbers of bacteria are within bacteria-containing vacuoles and dividing bacteria are evident (*). The gram-negative outer membrane can also be distinguished in TEMs as is indicated in the magnified insets at 48 h (>>). Bars, 500 nm. c Bacterial growth of ‘Ca. B. cookevillensis’ in A. polyphaga as confirmed by qPCR. ‘Ca. B. cookevillensis’ increased by 1.5 log10 when infected at an MOI of 1. Data represent means of two independent experiments performed in triplicate

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