| Abstract: | The hybrid plasmid consisting of pSC101 and the redB--N--imm region of phage lambda cI857 persists in cells grown at 30 degrees C but not in cells grown at 37 degrees C. In the latter case the plasmid was found to undergo several modifications. Restriction maps of these new plasmids indicate the following modifications: (1) the insertion of an IS1 element into gene N carried by the lambda fragment; (2) a mutation in the pL oL site of the same fragment, and (3) four large deletions (30 to 50% of the hybrid plasmid) which remove almost the entire lambda fragment. For the latter deletions, one endpoint seems to be fixed in the same restriction fragment of pSC101 while the other endpoint assumes four different positions on the lambda fragment; this might suggest a site-specific recombination event. |
