Organisms formed using 6-letter genetic code

Scientists have engineered the first ever ‘semi-synthetic’ organisms with an expanded, six-letter genetic code. ¬†Every living thing on Earth is formed according to a DNA code made up of four bases¬†(represented by the letters G, T, C and A), these modified organisms carry an entirely new type of DNA, with two additional DNA bases, X and Y, nestled in their genetic code.

http://www.sciencealert.com/new-organisms-have-been-formed-using-the-first-ever-6-letter-genetic-code