On Jan. 23, 2017, scientists at The Scripps Research Institute (TSRI) announced the development of the first stable semisynthetic organism.

The researchers, building on their 2014 study in which they synthesized a DNA base pair, created a new bacterium that uses the four natural bases (i.e. A, T, C and G), which every living organism possesses, but that also holds as a pair two synthetic bases called X and Y in its genetic code, and can hold on indefinitely to the synthetic base pair as it divides. Their research was published n the journal Proceedings of the National Academy of Sciences.