RNA dot hybridizations were first described by Kafatos et al. (1 ). They enable rapid detection of transcription from a number of different mRNA populations and are particularly useful in the initial characterization of cDNA clones isolated by differential screening. In cases in which many samples have to be handled, filtration manifold systems are available, such as the Millipore MilliBlot system, which use a vacuum source to transfer nucleic acid to filter.
