In preferred embodiments, the mutagen is selected from the group consisting of ethyl methanesulfonate, nitrosoguanidine, {TAIL ~ diethyl sulfate}, N nitroso N ethylurea, {HEAD ~ acetaldehyde}, diepoxyoctane, diepoxybutane, trimethylpsoralen followed by UV irradiation, 32P decay, and ionizing particles 
In preferred embodiments , the mutagen is selected from the group consisting of ethyl methanesulfonate , nitrosoguanidine , { TAIL ~ diethyl sulfate } , N nitroso N ethylurea , { HEAD ~ acetaldehyde } , diepoxyoctane , diepoxybutane , trimethylpsoralen followed by UV irradiation , 32P decay , and ionizing particles
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH