High-stringency subtraction for the identification of differentially regulated cDNA clones.

The technique of high-stringency subtraction described here facilitates subtractive hybridizations between directional cDNA libraries constructed in lambda ZAP II cloning vectors and represents an improvement on earlier methods for the subtraction of entire cDNA libraries. High-stringency subtraction is designed to eliminates the subtraction of differentially expressed cDNAs, which show similarity to constitutive sequences by the incorporation of a novel high-stringency wash step. This method also allows the size-selection of target cDNAs and incorporates an improved procedure for the synthesis of driver DNA used in subtractions.