Fig. 2. Identification of the TAGteam group of heptanucleotide sequences based on their relative over-representation upstream of pre-cellular-blastoderm genes. (A,B) Probability that the observed difference between pre-CB and post-CB genes with regard to the number of heptamer sites found within a 500-bp window at the specified distance from the transcription (txn) start site (+1) is the result of chance. The baseline cutoff is P=0.01 (-log[0.01]=2). (C,D) Comparison of the same pre-CB and post-CB genes with respect to the observed number of TAGteam sequences within 500 bp upstream of their transcription start sites versus the number expected based on %GC for the set. Gene sets are defined in Materials and methods (melanogaster: n=25 pre-CB versus 78 post-CB; pseudoobscura orthologs: n=24 pre-CB versus 70 post-CB).