SUMMARY: Histidine-independent (h) mutants induced in histidine-requiring (h) cultures by ultraviolet light have a delay in the onset of logarithmic increase that is about two generations longer than the delay shown by marked unirradiated h bacteria present at the same time. This extra delay is interpreted as being due to the segregation of one from four nuclei which are present, on the average, in growing h organisms. The same assumption accounts for the extra delay observed in spontaneous h mutants. These and other results are discussed in relation to the site of mutation and to the various types of delay that can retard the onset of growth of a mutant clone. It is concluded that in the mutation from h to h, the h condition is dominant in the heterocaryon, that whatever phenotypic delay exists is short, and that cell division is not required to pass through it.


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