1] New bacteriophage lambda vectors with positive selection for cloned insects

Abstract

Publisher Summary This chapter discusses new bacteriophage lambda vectors with positive selection for cloned inserts. Molecular cloning methods eliminated the necessity for physical fractionation of DNA and permitted, for the first time, the isolation of eukaryotic structural genes. Most bacteriophage vectors are substitution vectors that require internal filler fragments to be physically separated from the vector arms before insertions of foreign DNA. Genomic DNA is partially digested with restriction endonucleases to produce a population of DNA fragments from which molecules 15–20 kb long are purified by agarose gel electrophoresis. Other derivatives of 1059 that introduce defined amber mutations or alter the restriction enzyme sites on the vector have also been constructed. Successful and efficient cloning requires highly purified restriction enzymes and active DNA ligase.