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