The presence of {HEAD ~ the trpl lesion} as a characteristic of the yeast host cell genome than provides {TAIL ~ an effective environment} for detecting transformation by growth in the absence of tryptophan 
The presence of { HEAD ~ the trpl lesion } as a characteristic of the yeast host cell genome than provides { TAIL ~ an effective environment } for detecting transformation by growth in the absence of tryptophan
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH