pBluescript

In genetics, pBluescript (pBS) or pBluescript II is a commercially available phagemid containing several useful sequences for use in cloning with bacteriophage. The sequences include a multiple cloning site sequence (MCS), antibiotic resistance sequence to ampicillin and an E. coli and f1 helper phage origin of replication. The multiple cloning site sequence is located within a LacZ controlled gene designed to provide a blue coloration when expressed in bacteria. This is usually achieved via X-gal found in agarose growth media used to culture bacteria with pBS. If the gene is disrupted by successful insertion of a DNA sequence, the bacteria exhibit a white coloration in Blue white screening, distinguishing successful recombination from those phagemids which were not altered. These recombinant plasmids can then be used in a variety of molecular techniques. Determining expression and developing genomic libraries are some applications for which the pBS recombinants can be used.