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