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Scientist finds a whole new 'domain' of life

It is life but not as we know it – a scientist claims to have discovered not just a new species but a whole new branch of the tree of life.

Living things are currently split into three branches or domains – eukaryotes, or complex celled organisms such as animals, plants and humans – and two simple celled microorganism divisions – bacteria and archaea.

But now a researcher working with the laboratory of the maverick scientist Dr Craig Venter claims he might have discovered a fourth.

Professor Jonathan Eisen, an evolutionary biologist at the University of California, has used complicated gene sequencing techniques to look at DNA collected by Dr Venter on a round the world yachting trip.

He found that some of the genes did not fit into the three domains and that he could possibly have stumbled on a whole new domain.

Trying to classify the new DNA has proved impossible and so Prof Eisen has published his findings in the journal Public Library of Science in the hope others can help.

"The question is, what are they from?" said Prof Eisen.

"They could represent an unusual virus, which is interesting enough. More interestingly still, they could represent a totally new branch in the tree of life.

"Even though we did not have the story completely pinned down, we decided to finally write up the paper to get other people to think about this issue."

One of the difficulties of trying to study novel genes is that it is hard to culture them to such a quantity to make them easily readable.

But Prof Eisen used methods honed by Dr Venter in his successful attempt to read the human genetic code.

They have dubbed the technique as “metagenomics” and it involves breaking down the DNA to sizeable chunks, decoding them and then reassembling in the correct order.

The science benefits greatly from ever more powerful and cheaper computers.

The team applied the technique to seawater samples collected between 2003 and 2007 from the world's oceans by Dr Venter on his yacht, Sorcerer II.

Prof Eisen stumbled on variations of two genes called RecA and RpoB, both of which are old and abundant, which had different characteristics to anything in the public genetic databases.

Research into classifying the findings go on but one of the problems is that it is not known where the genes come from – they are simply taken from samples of seawater.

© Telegraph.co.uk