Abstract: Disclosed herein are compositions, methods, cells, engineered microorganisms, and kits for increasing the production of proteins or polypeptides comprising one or more unnatural amino acids. Further provided are compositions, cells, engineered microorganisms, and kits for increasing the retention of unnatural nucleic acids encoding the unnatural amino acids in an engineered cell, or semi-synthetic organism.

Abstract: Disclosed herein are methods of reverse transcribing a polynucleotide comprising an unnatural ribonucleotide comprising reverse transcribing the polynucleotide with a reverse transcriptase in the presence of an unnatural dNTP comprising an unnatural nucleobase, wherein the reverse transcriptase polymerizes cDNA into which the unnatural NTP is incorporated. In some embodiments, the polynucleotide is present at a concentration less than or equal to about 500 nM and/or the polynucleotide is a tRNA, mRNA, RNA aptamer, or a member of a plurality of RNA aptamer candidates.

Abstract: Provided herein are eukaryotic semi-synthetic organisms and their methods of use and manufacture.

Abstract: Disclosed herein are compositions, methods, cells, engineered microorganisms, and kits for increasing the production of proteins or polypeptides comprising one or more unnatural amino acids. Further provided are compositions, cells, engineered microorganisms, and kits for increasing the retention of unnatural nucleic acids encoding the unnatural amino acids in an engineered cell, or semi-synthetic organism.