Mirna transcriptome methods and compositions

Abstract

Methods, polynucleotides, kits, and reaction mixtures are disclosed for the enriching of short polynucleotide molecules that have a length within a desired target length range. A Type IIS or Type III restriction enzyme is used to cleave polynucleotides at cleavage sites located at a distance from the restriction enzyme recognition sites. For example, a mixture of polynucleotides can be formed by inserting DNA molecules between a recognition site for the restriction enzyme and a region of non-naturally-occurring nucleotides that block cleavage by the restriction enzymes. If a polynucleotide contains a DNA molecule with a length within a target range, then the cleavage site will be within the blocking region, and cleavage will not occur. Polynucleotides containing DNA molecules with lengths outside the target range can be cleaved. By selectively enriching, through PCR or other means, polynucleotides that are intact, a concentrated population of polynucleotides of a target length can be formed.