The pUC series of plasmid cloning vectors by Vieira and Messing was developed from the M13 system and were the first plasmids constructed to take advantage of this screening method. In this method, DNA ligated into the plasmid disrupts the α peptide and therefore the complementation process, and no functional β-galactosidase can form. Cells transformed with plasmid containing an insert therefore form white colonies, while cells transformed with plasmid without an insert form blue colonies; result of a successful ligation can thus be easily identified by the white coloration of cells formed from the unsuccessful blue ones.
