Transcription of an expanded genetic alphabet

The unnatural base pairs d5SICS:dMMO2 and d5SICS:dNaM are selectively transcribed by T7 RNA polymerase and the efficiency of d5SICS:dNaM transcription in both possible strand contexts is marginally reduced relative to that of a natural base pair. The results have shown that d5SICS:dNaM is both replicated and transcribed with efficiencies and fidelities that is sufficient for use as part of an in vitro expanded genetic alphabet.