the present invention is directed to methods for the production and isolation of nucleic acid molecules . in particular , the invention concerns isolation of mrna molecules and the production and isolation of nucleic acid molecules , which may be single - or double - stranded . additionally , the invention concerns selection and isolation of particular nucleic acid molecules of interest from a sample which may contain a population of molecules . specifically , the invention concerns affinity - labeled primer - adapter molecules which allow improved isolation and production of such nucleic acid molecules , increasing both product recovery and speed of isolation .