Transcriptional organization of the chromosomal ben-cat region. (A) The number of nucleotides in noncoding regions is shown in parentheses. Transcriptional units and directions are denoted by horizontal arrows in the upper panel. The designation and location of primers used for RT-PCR are in the lower panel. A pair of oligonucleotide primers is marked with a convergent arrow. (B) RT-PCR analysis of mRNA transcripts using gel electrophoresis of amplified cDNA fragments. The first and last lanes were loaded with molecular size markers. +, in the presence of inducer benzoate; -, in the absence of inducer benzoate.