Table 1. Summary of PolyA_DB version 3.1.

Species	Human	Mouse	Rat	Chicken
No. of samples used	24	59	11	9
No. of PAS reads used	59 090 907	153 989 213	23 616 600	29 104 491
No. of PASs	108 042	202 426	61 905	65 909
No. of genic PASs	85 275	121 163	36 941	45 116
No. of genes listed	20 998	21 588	14 529	12 292
No. of genes with 3′ end extension	8962	12 027	8302	8352
Median 3′ end extension size (nt)	758	469	617	1062
No. of mRNA genes	15 977	17 846	14 077	12 130
No. of ncRNA genes	5021	3742	452	162