Oligo 1(top strand for sense):5'-GGATCCTAATACGACTCACTAATA-G 1 N 2-18 C 19-3'(G 1 N 2-18 C 19 =sense ... 3'-CCTAGGATTATGCTGAGTGATAT-C 1 N 2-18 G 19 (sense)-AAGTTCTCT(loop)-C 19 N 18-2 G 1 ...