On May 7, 2014, scientists at The Scripps Research Institute (TSRI) announced that they had engineered a bacterium whose genetic material includes an added pair of DNA ﾓletters,ﾔ or bases, not found in nature. The cells of this unique bacterium can replicate the unnatural DNA bases more or less normally, for as long as the molecular building blocks are supplied. The The report was published in the journal Nature.