Description_x000D_ General description_x000D_ The pUC19 plasmid (2,686 bp) confers ampicillin resistance and complement defects in β-galactosidase in appropriate host strains. The multiple cloning site (MCS) is within the B-galactosidase gene; the plasmid has thirteen unique sites in the MCS (Acc I, BamH I, EcoR I, Hinc II, Hind III, Kpn I, Pst I, Sac I, Sal I, Sma I, Sph I, Xba I, and Xma I)._x000D_ Application_x000D_ Plasmid DNA from Escherichia coli RRI has been used for imaging of DNA (nanostructure) via atomic force microscopy._x000D_ Biochem/physiol Actions_x000D_ These plasmids confer ampicillin resistance and complement defects in β-galactosidase in appropriate host strains. The multiple cloning site (MCS) is within the β-galactosidase gene; pUC8 and 9 have nine unique sites within the MCS while pUC18 and 19 have thirteen._x000D_ Foreign DNA inserted at the MCS abolishes the ability to catabolize lactose. Lactose-positive, ampicillin-resistant colonies (host strain containing plasmid) form blue colonies on plates containing ampicillin and X-Gal; lactose-negative, ampicillin-resistant colonies (host strain containing plasmid with foreign DNA inserted at the MCS) form white colonies on this medium. The orientations of the MCS regions in the pUC plasmids are analogous to those of the corresponding M13 phage._x000D_ Components_x000D_ pUC19 Plasmid DNA, 10 μg is supplied at approximately 0.5 mg/ml in 10 mM Tris-HCl (pH 8.0) with 1 mM EDTA._x000D_ Principle_x000D_ Foreign DNA inserted at the MCS interrupts the β-galactosidase gene and abolishes the ability to catabolize lactose. Lactose-positive, ampicillin-resistant colonies (host strain containing plasmid) form blue colonies on plates containing ampicillin and X-Gal; lactose-negative, ampicillin-resistant colonies (host strain containing plasmid with foreign DNA inserted at the MCS) form white colonies on this medium.