Integrated oligonucleotides

An integrated oligonucleotide having from about 16 to about 110 nucleotides, wherein said oligonucleotide includes a duplex forming region that forms a duplex with a target nucleic acid, a triplex forming region that forms a triplex with the duplex formed between the duplex forming region and the target nucleic acid, and a linker region connecting the duplex forming region and the triplex forming region, wherein the duplex forming region is from about 8 to about 50 nucleotides in length and has at least one C nucleotide, and wherein each of the duplex- and triplex-forming regions is comprised of both purine and pyrimidine nucleotides, and the triplex has a melting temperature above 56.degree. C., provided that there is no intercalating agent covalently bound to the integrated oligonucleotide's 5' end and neither the duplex- nor triplex-forming regions contain two or more consecutive purine nucleotides.