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