| 摘要 |
DNA segments from mutants can be obtained very straightforwardly by isolating from the strain to be mutated the total DNA, cleaving the latter into small fragments and integrating into a temperature- sensitive plasmid with another selection marker which is selectable in E. coli, transforming the hybrid plasmid population obtained in this way into the starting strain, selecting the transformants by selection for the marker, eliminating the hybrid plasmids by raising the temperature above the threshold of the temperature-sensitive plasmid, and selecting the mutants by renewed selection for the marker. Construction of a cosmid gene bank with the DNA of these mutants results, by selection for the marker which has been introduced and is selectable in E. coli and for the cosmid-intrinsic marker, directly in cosmids which contain the mutated gene. |
