Oligonucleotide designed from a block of sequence identity located within the highly conserved region of pbs second intron containing 32bp motif r1 and 7bp motif r2, governing expression of lacZ.
49bp synthetic oligonucleotide, containing a 32bp motif that is repeated within the second intron, is inserted upstream and in same orientation to lacZ.
Weak pairing sensitivity conferred the synthetic oligonucleotide.