Fig. 1

Comparison of GC contents between BDPs and randomly selected UDPs. Type I, II and III BDPs: bidirectional promoters with intergenic sizes ranging from 0 to 250 bp; from 250 to 500 bp and from 500 to 1000 bp, respectively. R I, RII and RIII: randomly selected unidirectional promoters (UDPs) with sizes as 250 bp, 500 bp and 1000 bp starting from upstream of TSS of the downstream genes, respectively, were used as controls for type I,II and III BDPs, respectively. Statistical analysis was conducted with a two-sample K-S test