Isolation and biochemical analysis of plant small RNAs.

Small RNAs, defined as noncoding 20-30-nt-long RNAs, are instrumental regulators of cellular processes in most eukaryotes. In this chapter we describe three methods for extracting small RNA from cells: a general method, one plant specific and a third particular to conifers. Further, protocols are given for the analysis and quantification of small RNAs using polyacrylamide gel-based approaches. A native streptavidin gel-shift assay, useful for measuring the relative amounts of multiple small RNAs simultaneously, is presented. To further characterize small RNAs biochemically, a sodium periodate assay probing for 2', 3' hydroxyl groups on the 3' terminus of small RNAs is outlined.