Localization of the bacterial sources of proteins in <i>Acyrthosiphon pisum</i> honeydew.

<p><b>A</b>. Semithin section of <i>A. pisum</i> showing the bacteriome (bm) containing bacteriocytes around the aphid alimentary canal. <b>B–D</b>; Transmission electron microscopy micrographs (TEM) of semi-thin sections. In panel (<b>B</b>), the ultrastructure of hindgut epithelial cells shows the replacement of old tissues, which are expelled and degraded into the lumen. Panel (<b>C</b>) shows the primary symbiont <i>Buchnera aphidicola</i> (ps) within a bacteriocyte. Buchnera cells are round and packed into bacteriocyte cytoplasm. The same panel shows that the lumen of the hindgut (hg) appears to be filled with bacteria from gut microbiotae (gf). In panel (<b>D</b>), the secondary symbiont <i>Serratia symbiotica</i> (ss), which has been indirectly determined by PCR, is enclosed in the cytoplasm of aphid cells in the bacteriome. Scale bars = 500 µm in A, 3 µm in B, 5 µm in C and 1 µm in D. Abbreviations: ac: Alimentary canal; bm: Bacteriome; hg: Hindgut; mg: Midgut; hl: Hindgut <i>lumen; ps: Primary</i> Symbionts; ss: Secondary Symbionts; gf: Gut flora; he: <i>Hindgut</i> epithelium; er: epithelium renewal.