Fig. 5

FISH observation of Deferribacteres cells in the midgut of an adult male R. exoculata using newly designed probes [12]. These long filamentous bacteria (b) are inserted between the microvilli (m) of the intestine epithelium (e) of the host. Eukaryote nuclei (n) at the center of epithelial cells are labeled with DAPI (blue). The apical brush border of the epithelium with the microvilli (represented by the white line just beside the legend m) is all along the lumen (l). Bacterial cells (b) are co-hybridized with the Eubacterial probe (Eub338, colored in white on the image) and with the specific Deferribacteres symbiont probe (Def1229, colored in red on the image), so they are visible in pink on the image