title: Non-random variability in evolution of base compositions of ribosomal RNA.
mesh_terms: D000225:Adenine / Q000032:analysis*; D000663:Amphibians; D000818:Animals; D001407:Bacillus; D001412:Bacillus subtilis; D005075:Biological Evolution; D001717:Birds; D002689:Chlamydia; D003596:Cytosine / Q000032:analysis*; D004330:Drosophila; D004447:Echinodermata; D004754:Enterobacter; D004926:Escherichia coli; D005658:Fungi; D006147:Guanine / Q000032:analysis*; D006801:Humans; D008322:Mammals; D008928:Mitochondria; D010945:Plants, Edible; D011549:Pseudomonas; D012313:RNA / Q000032:analysis*; D012270:Ribosomes; D013045:Species Specificity; D014498:Uracil / Q000032:analysis*; D003313:Zea mays
chemical_list: D014498:Uracil; D006147:Guanine; D012313:RNA; D003596:Cytosine; D000225:Adenine