Average base abundance at each position of the 201-nucleotide polyadenylation site region, showing the U-A-U-SiteA-U base abundance pattern in plants and animals. Plants: Arabidopsis thaliana, Medicago truncatula, Oryza sativa, Populus trichocarpa, Solanum lycopersicum, Sorghum bicolor, and Zea mays. Animals: Bos taurus, Danio rerio, Drosophila melanogaster, Gallus gallus, Homo sapiens, Mus musculus, Pongo abelii, Rattus norvegicus, and Taeniopygia guttata. Note that the base composition showed several clear differences between plants and animals. For example, the upstream A peak was lower but the U peak was higher in plants in comparison with animals. The shape of the downstream U peak was flat in plants but more pointed in animals. There was also a small A peak at position −3 in plants and position −5 in animals in addition to the U-A-U-SiteA-U (or U-A-U-A-U) base abundance pattern.