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