Figure 4.

Identification of putative alien (PA), highly expressed (PHX) and moderately highly expressed (PX) genes. For each gene belonging to the HIP1^less set (having to few HIP1 motifs for its size) we calculated the codon usage bias against two set of genes: a) the mean codon usage of all genes in the genome B(F|C); and b) the codon usage of ribosomal proteins B(F|RP) which are expected to be highly expressed. Genes with a codon usage suggesting a high (PX) and very high (PHX) level of expression are shown in blue and green respectively. Genes with a codon usage suggesting a xenolog origin (PA) are shown in red. The rest of the genes belonging to the HIP1^less set that didn't meet the criteria to be included in PA, PX or PHX sets are shown in gray.