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