In another embodiment the mutagen is {HEAD ~ γ irradation}, ultraviolet irradiation, or {TAIL ~ X irradiation} 
In another embodiment the mutagen is { HEAD ~ γ irradation } , ultraviolet irradiation , or { TAIL ~ X irradiation }
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL