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