An improvement on labelled messenger RNA preparation for DNA-RNA hybridisation

An improved method for the removal of DNA and phenol residues after phenol extraction in m-RNA preparation has been developed. This involves repeated freeze-thaws of the aqueous layer under centrifugal force. As a model assay, five minutes pulse-labelled lambda cI47 late m-RNA is prepared and hybridised to the r-strain lambda DNA. After the centrifugation treatment, non-specific hybridisation is reduced to one-tenth of the untreated sample and the background with respect to input radioactivity for hybridisation is reduced to 0.3%. This low background m-RNA preparation is important especially in dealing with minor class m-RNA.