Sequence encoding a GAL4 driver is recombineered into a construct carrying an 84 kb genomic fragment that includes the 30 kb transcription unit of Oct-TyrR and 42 kb genomic DNA upstream and downstream of the Oct-TyrR transcription start site extending into one or more adjacent genes on each side. GAL4 is inserted into the position of the first ATG of Oct-TyrR in such a way that it is presumably expressed under the control of Oct-TyrR regulatory sequences.