hox genes physical map, hoxE and xisH promoters, and analysis of cotranscription in Lyngbya majuscula CCAP 1446/4. (A) Physical map of the L. majuscula genome region containing the hox genes, (B) analysis of the hox genes cotranscription by RT-PCR, and (C, D) nucleotide sequences of the promoter regions upstream of hoxE and xisH. A schematic representation of the cDNAs and the products generated in the RT-PCRs are depicted below the physical map. Lanes 1: RT-PCR; Lanes 2: Negative control without reverse transcriptase; Lanes 3: Negative control (no template); Lanes 4: PCR positive control (genomic DNA); M: GeneRuler DNA Ladder mix (Fermentas). M*: 100 Base-Pair Ladder (GE Healthcare). Within the hoxE and xisH promoter regions the following regions are indicated: putative LexA binding sites, putative IHF binding sites (boxed with the mismatching nucleotide shaded), the -10 and -35 boxes and the ribosome binding site – RBS (underlined), the transcription start point (+1, bold and underlined), and the start codons of hoxE and xisH (bold and underlined).