Novel methods for quantification of micrornas and small interfering rnas

A method for quantitative determination of a short-length RNA, which has a length of at most 100 nucleotides, comprising the steps of:

• a) contacting the target nucleotide sequence with two oligonucleotide tagging probes each comprising an anchor nucleotide sequence and a recognition nucleotide sequence, wherein said recognition nucleotide sequence is complementary to the target sequence, and wherein the recognition sequence of the first tagging probe hybridizes to a first region of the target sequence and the second recognition sequence of the second tagging probe hybridizes to a second region of the target sequence adjacent to the first region of the target sequence;
• b) joining the two adjacent recognition sequences of the hybridized tagging probes covalently by ligation to form a contiguous nucleotide sequence, comprising a sequence complementary to the target nucleotide sequence and the two anchor nucleotide sequences, and
• c) quantifying the ligated oligonucleotide molecules by PCR using primers corresponding to the anchor nucleotide sequences and a labelled detection probe comprising a target recognition sequence and a detection moiety.