Amino acid metabolism gene expression profiling during pea aphid development. A) Hierarchical clustering (generated by an average linkage method with euclidean distance and no leaf order optimization) of the 135 amino acid metabolism genes annotated by Wilson et al.. The colour chart indicates expression intensities using a base 2 logarithmic scale: blue and red represent, respectively, the lower (2.0) and upper (16.0) expression intensities (see bottom panel legend). On the right of the cluster we reported: in black, the genes varying significantly in at least one of the comparisons, with the exception of the ACYPI007803 gene, shown in green, and ACYPI004243, shown in purple. The three other genes coding the 18.104.22.168 enzyme activity are highlighted in grey but do not vary significantly during development. B) Final steps of the pathway for phenylalanine and tyrosine biosynthesis encoded in the pea aphid genome. C) Expression profiles of the genes involved in the pathway for phenylalanine and tyrosine biosynthesis in the pea aphid. Expression intensity is given as log2. Expression intensities of each stage are means of the three biological replicates.