SOME VIRUSES HAVE A COMPLETELY DIFFERENT GENOME TO THE REST OF LIFE ON EARTH

In the world of microbial warfare some times you have to change the very fab. Viruses that infect bacteria fittingly called bacteriophages - and their prey have been at war for eons, each side evolving more devilish tactics to infect or destroy each other. Eventually, some bacteriophages took these arms to a new level by changing the way they code their DNA. 

At least, that's what we think happened. Once thought to be an outliner, new research published in three separate papers shows that there's a whole army of bacteriophages with nonstandard DNA, which researchers called az- genome. 

''Genomic  DNA is composed of four standard nucleotides. These nucleobases from the genetic alphabet, ATCG, which is conserved across all domains of life'', biologists Michael Grome and Farren Isaac wrote in a recent Science editorial. 

''However, in 1977 the DNA virus cyanophage S-21 was discovered with all intense of 'A' substituted with 2 - aminoadinine (z) throughout its genome forming the genetic alphabet ZTCG''. Although scientists were fascinated, no other bacteriophages were found with the z-genome, and with the difficulty of culturing S-21 in a lab, the z-genome was set aside as a curiosity now, research documented in three separate studies from researchers in France and China shows that this was not a one-off, whilst also characterizing how the z-genome works and it's assembled. 

''Scientists have long dreamed of increasing the diversity of bases. Our work shows that nature has already come up with a way to do that''. One of the teams, led by first author Yan Zha from the Tianjin University, wrote in their paper all three teams searched genetic sequence databases for the sequences relating to their proteins and enzymes and found a wide variety of bacteriophages with similar genes''. 

''The authors have done amazingly comprehensive job on showing that this is not one crazy outlier, but there's a whole group of bacteriophages that have this kind of genetic material'', Jef Boeke, a molecular biologist at New York University who was not involved in the work, told The Scientist.