Fig. 3.

The effective number of codons (ENC) in astroviruses and their hosts. ENC-values are plotted against the proportion of G + C in the 3rd synonymous codon position (GC3) for the three ORFs of astroviruses as well as for nuclear genes of their hosts (lower panel). The bell-shaped curve marks the unbiased synonymous codon usage as a function of GC3. Symbols used for the viruses and their hosts are: human—open triangles, turkey—open circles, ANV—open diamonds, mink—closed squares, sheep—closed circles, cat—closed triangles, and pig—closed diamonds.