Abstract: It is one objective of the present invention to obtain reproducible representations of expressed mRNA molecules by exploiting a novel technique that relies on short, single stranded polynucleotide tags. In one preferred embodiment, only one polynucleotide tag is obtained from each mRNA molecule, and relatively simple counting statistics can thus be applied after identification and sampling of the different tags, or a subset of tags being present in the population of representative tags. The tags according to the present invention are preferably single stranded polynucleotide tags obtained by subjecting genetic material derived from a biological sample to at least one site-specific nicking endonuclease capable of i) recognizing a predetermined nucleotide motif comprising complementary nucleotide strands and ii) cleaving only one of said complementary strands in the process of generating the at least one single stranded polynucleotide tag.

Abstract: It is one objective of the present invention to obtain reproducible representations of expressed mRNA molecules by exploiting a novel technique that relies on short, single stranded polynucleotide tags. In one preferred embodiment, only one polynucleotide tag is obtained from each mRNA molecule, and relatively simple counting statistics can thus be applied after identification and sampling of the different tags, or a subset of tags being present in the population of representative tags. The tags according to the present invention are preferably single stranded polynucleotide tags obtained by subjecting genetic material derived from a biological sample to at least one site-specific nicking endonuclease capable of i) recognizing a predetermined nucleotide motif comprising complementary nucleotide strands and ii) cleaving only one of said complementary strands in the process of generating the at least one single stranded polynucleotide tag.