RNA dot hybridizations were first described by Kafatos et al. (1 ). These hybridizations allow rapid analysis of mRNA expression and are particularly useful in the initial characterization of clones derived from differentially expressed genes. Where accurate quantification of transcription is necessary, or many samples have to be handled, filtration manifold systems are available such as the Millipore MilliBlot system (Bedford, MA), which uses a vacuum source to transfer nucleic acid to filter.
