Methods for tailing and ligation are well-known in the art. [0126] Cleaving a Base Portion of the Non-Canonical Nucleotide to Create an Abasic Site [0127] The polynucleotide comprising a non-canonical nucleotide is treated with an agent, such as an enzyme, capable of generally, specifically, or selectively cleaving a base portion of the non-canonical deoxyribonucleoside to create an abasic site.