COA on amino acid usage for encoded proteins of N. equitans. (a) Position of genes on the plane defined by axis 1 and axis 2. The upper and lower clusters of genes mainly encoding membrane-associated proteins are marked by dashed-line ovals. (b) Position of genes on the plane defined by axis 1 and axis 3. Black quadrangle and pink quadrangle represent highly expressed and other genes respectively.
Das et al. BMC Genomics 2006 7:186 doi:10.1186/1471-2164-7-186