The RNA population in any given cell is remarkably complex and unique. RNAs come in a number of different species and sizes that range from a few to many thousand nucleotides. Given the sheer number and diversity of eukaryotic RNA molecules, it is of obvious interest to study specific RNAs within a given cell or tissue.
There are numerous methods to detect specific RNAs All differ in their capabilities in the areas of sensitivity, quantification dynamic range, throughput, and revealing additional information about the RNA species under study (e.g RNA size and structure).
Isolating high-quality RNA molecules is crucial to many downstream experiments, such as cloning, for cDNA library creation, sequencing and structural analysis. Aside from the techniques mentioned above, there are many techniques that seek to enrich the entire population of a particular RNA species. Studies that require the isolation of mRNA often take advantage of the polyadenine tail typically present at the 3’ end. One approach involves the use affinity matrices; poly-T oligonucleotides that hybridize to the complementary poly-A tails (1). Enrichment of miRNA and siRNAs can also be achieved using high-affinity binding proteins and the use of chitin magnetic beads (2, 3).
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