Upstairs electron microscope image four   nanoarqueas   attached to the right side of a cell of   Ignicoccus.   Below on the left, we see that   nanoarqueas   fail to fuse with the   Ignicoccus,   although sticking to it. /   NATURE

New type of living 10 times smaller than a bacterium

Only a huge coincidence has allowed Dr. Karl Stetter discover the enigmatic being alive just baptized as   nanoarquea. Their size is about 10 times lower than that of a typical bacteria. Genome, too. He lives next to another microbe, 120 meters below the waters north of Iceland, and no technique to use would have given him without a great stroke of luck.

The standard model of biological evolution divides all living things existing in three vast realms: 1) bacteria, 2) archaea (similar to bacteria, but adapted to extreme conditions) and 3) the eukaryotes, which include all animals, plants and protists (such as amoeba and paramecium).

This, contrary to all intuition, tripartite classification is based on comparing the   ribosomes,   complex universal machines that manufacture the proteins of all living beings. By that look very similar bacteria and archaea, their ribosomes are very different. And no matter how different they may seem Gladioli and humans, their ribosomes are very similar.

Karl Stetter, leading a team from the University of Regensburg and the Max Planck Institute in Heidelberg (both in Germany), was studying microbes in the deep ocean in an area north of Iceland, where underwater volcanic activity heats the water at some points to almost the boiling temperature. Can already be considered a success in itself that there Stetter discovered a new bow, which has called  Ignicoccus.

But the biggest surprise of her career she has been found attached to the surface   Ignicoccus: a tiny microbes only 0.4 microns in diameter (a micron is one thousandth of a millimeter, bacteria and archaea common measure between 4 and 10 microns, see photo). The researchers, who presented their findings today at   Nature, have called this dwarf lifestyle   Nanoarchaeum equitans   (As in  equitans   refers to   ride   on   Ignicoccus), and propose to call   nanoarqueas   their course group.

The first thing I did was examine their ribosomes Stetter to see what biological kingdom belonged (to be exact, what the evolutionary biologists is to examine the genes that contain the information to make certain essential parts of the ribosome). Ribosomes but nanoarquea   turned out to be even stranger than their size: they were clearly distinct from the ribosomes of archaea, bacteria and eukaryotes. That is, all living things other than described to date. But look a little closer to the ribosomes of archaea than of the other two kingdoms. This, coupled with these microbes living at temperatures near 100 degrees -like Ignicoccus   and many other archaea, has decided to Stetter to classify them as a new type of archaea (hence the name   nanoarqueas).

Some evolutionists believe that microbes living at temperatures near 100 degrees are direct descendants of the first living things on Earth, as the planet took hundreds of millions of years to cool after formation. The   nanoarqueas   not only comply with this condition, but have only a few hundred genes (instead of a few thousand, as the normal microbes). Could they represent the most primitive beings on the planet?

Stetter responded yesterday to this newspaper: "Of course, there are intriguing possibilities that   Nanoarchaeum   is revealed as a   survivor   primitive Earth '. Could the merger of several of these dwarf forms have led to the first cell of the planet? 'Yes, and even a fusion event between similar organisms to   nanoarqueas   could have given rise to the first eukaryotic cell. ' Stetter hastens to add: 'Soon there will be news: the genome   Nanoarchaeum   just been sequenced by Diversa Corp., a company in San Diego (USA). We are very excited to see what they themselves dwarf genes from our beloved '.

Nanoarchaeum   not grow by itself in conventional crops biologists, and the strangeness of their ribosomes have prevented discover through   hooks   Common genetic. Stetter now knows how to find his kind, and no one dares to predict how many more will appear in the coming years.

Nature