Gene expression regulations acting on the integrated pathway for tyrosine and other precursors of the cuticular tanning biosynthesis in a pea aphid embryo associated with B. aphidicola . A) Schematic representation of the pea aphid embryo (green rectangle) and its symbiotic bacteria (grey rectangle). A summarizing diagram of the Tyr/dopamine pathway during pea aphid development is represented. Black arrows represent reactions, grey arrows transport reactions; solid arrows are annotated events; dotted arrows are possible events; red crosses indicate events not present in the annotation of the genome (see text for details). Only the pea aphid genes whose expression levels change significantly during development are represented. The two B. aphidicola genes did not show significant expression changes during pea aphid development . B) Expression profiles of the genes involved in the Tyr/dopamine pathway in the pea aphid. Expression intensity is given as log2. Expression intensities of each stage are means of the three biological replicates.