The recombinant plasmid pPGVT3 derived from the vector pUC4 was unstable in the E.

• 从载体质粒pUC4衍生的重组质粒pPGVT3在大肠杆菌宿主DF2145中是不稳定的,以pPGVT3转化DF2145时在4o℃培养得不到转化子。