The polymerase chain reaction may also be performed on a library of cloned nucleic acid fragments wherein {HEAD ~ the sequence} of {TAIL ~ one primer} is derived from the instant nucleic acid fragments, and the sequence of the other primer takes advantage of the presence of the polyadenylic acid tracts to the 3′ end of the mRNA precursor encoding plant genes 
The polymerase chain reaction may also be performed on a library of cloned nucleic acid fragments wherein { HEAD ~ the sequence } of { TAIL ~ one primer } is derived from the instant nucleic acid fragments , and the sequence of the other primer takes advantage of the presence of the polyadenylic acid tracts to the 3′ end of the mRNA precursor encoding plant genes
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 TAIL 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH