Yeast artificial chromosome (YAC) libraries stored in microtiter plates are available for screening as either complex PCR pools or hybridization filters generated from YACs gridded at high densities (seeChapter 57 ). Different libraries may be available as either PCR pools, hybridization filters, or both. Consequently, screening strategies have been designed that rely solely on either technique, or use a combined approach. Clearly, access to the YAC library microtiter plates and an automatic gridding system allows the user greater flexibility and is an advantage in large mapping projects.
