Microelectrophoretic Technique for Fractionation of RNA

Abstract

GEL electrophoresis separates RNA fractions with higher resolution than the commonly used techniques of column ehromatography and sucrose density gradient centrifugation^1–3. Filtration in gel electrophoresis of RNA is well documented^2,4–6 and several electrophoretic media have been examined: agar^1,7, agarose³, starch⁸ and polyacrylamide (refs. 4 and 6 and unpublished work of U. Grassbach and I. B. Weinstein). For the microanalysis of RNA base composition⁹, electrophoresis can be scaled down over a wide range by adopting a system in which the overall dimensions are reduced, the diffusion is restricted by greatly increased viscosity and the migration rate is still sufficient because of a very steep voltage gradient. In spite of such a high field strength there is no problem of inadequate cooling because there is a favourable ratio of surface to volume. We report here that gel electrophoresis can be similarly modified, and describe a procedure which permits fractionation of native RNA in amounts of 10⁻⁹ to 10⁻¹⁰ g.