Screening large-insert libraries by PCR.

This unit describes procedures for screening large-insert libraries by multistep polymerase chain reaction (PCR) analysis of DNA samples from clone pools. In the basic protocol, PCR amplification and agarose gel electrophoresis are used to identify successively smaller pools of DNA or colonies that contain clones with the appropriate-sized amplification product. In the last screening step, individual clones are identified. The first and second support protocols describe the preparation of DNA and yeast-cell pools for screening, and the first alternate protocol describes the preparation of crude lysates suitable for PCR from individual clones or small-scale pools.