Summary: Five mutants of strain 2 (ColE1), initially detected because they released little or no colicin when tested on solid medium, proved to be sensitive to ultraviolet light (u.v.). Further testing indicated that one of the mutants was deficient in genetic recombination and was probably a -type mutant, while three of the others were deficient in DNA polymerase activity and appeared to be typical mutants. The fifth mutant was less sensitive than the others to methyl methanesulphonate, showed reduced proficiency in genetic recombination, and was of approximately normal u.v. mutability. This mutant may be a counterpart of the class known as in . All five mutants degraded significantly more of their DNA following exposure to u.v. than did the wild-type strain. The -type mutant and the possible mutant also degraded significantly more of their DNA spontaneously than did the wild-type. Treatment with visible light and acridine orange (photodynamic treatment) caused no significant degradation of DNA in the wild-type strain, a highly significant increase in the extent of DNA degradation in a mutant, and a decrease in the extent of degradation in the -type mutant.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error