tokens: PCR products showing PTT shifts were directly sequenced , and mutations confirmed by restriction enzyme digestion where possible .
folded_tokens: pcr products showing ptt shifts were directly sequenced , and mutations confirmed by restriction enzyme digestion where possible .
labels: B-DNA_molecule I-DNA_molecule O B-other_name O O O O O O O O O B-other_name I-other_name I-other_name O O O