Production of a subtracted cDNA library

For some experiments, a complete cDNA library is unnecessary and instead, a subtracted cDNA library is useful. A subtracted cDNA library contains cDNA clones corresponding to mRNAs present in one cell or tissue type and not present in a second type. This cDNA library is used to isolate a set of cDNA clones corresponding to a class of mRNAs, or to aid in the isolation of a cDNA clone corresponding to a particular mRNA where the screening procedure for the cDNA clone is laborious because a specific DNA or antibody probe is unavailable. Since relatively few recombinants are obtained after subtraction, this protocol is for a cDNA library constructed in the lambda>10 vector or its equivalent, which allows a high cloning efficiency and permits elimination of nonrecombinants; however, the protocol can be used to produce subtracted cDNA libraries in any vector system.