Figure 2. Primer extension identification of transcription start sites of the MdHexL1 (A) and MdHexF1 (B) genes of Musca domestica. Lanes A,C,G and T correspond to the DNA sequence reactions in which the dideoxynucleotides A,C,G and T were used respectively and lanes R indicate the primer extension reactions (note that the nucleotide sequences, 5' at the top and 3' at the bottom, represent the complementary DNA strand, so that it may be read directly as in figures 1A and 1B).The nucleotides indicated in bold correspond to the transcription start site.