Friday, 2 December 2011

Say hello to granpa LUCA

About a year ago I was reading the last pages of a semi-scientific adventure book: "The Fifth Day" by Frank Schatzing. Without spoiling too much (in case someone else is going to read it), I've found two intriguing concepts in the story: one, we may not be the most intelligent and powerful species on earth, and two, maybe we share this planet with other forms of intelligent organisms, so different in their appearance and biological organization that we may not even recognize them, until they want to directly interact with us... But even more fascinating to me is the fact that the author imagines a giant multicellular organism spread upon the oceans in which every single cell is as well a separate entity and a part of a super-organism communicating by a complex exchange of DNA molecules. Maybe this is not so cool compared to Indiana Jones adventures, but what can be more fascinating for a lab guy working on genetics?
Ok, now I've found in recent scientific papers that this super-organism hypothesis may be closer to a real fact that to a science-fiction story. With the exponential rise in the accumulation of genomic and proteomic data from a lot of different organisms, both eukaryotes and prokaryotes, a lot of efforts have been also made in recent years trying to reconstruct the features of the Last Unique Common Ancestor... LUCA the grandpa of us all!
LUCA is considered the unique organism that pre-date Eukarya, Bacteria and Archea and its study can provide useful information on the essential biochemical and genetic mechanisms of a cell. Based on the papers published in the last 2 years, LUCA seems to be a kind of RNA-based super-organism, huge mix of cells that span across primordial oceans constantly exchanging pieces of RNA and useful proteins in an attempt to obtain an efficient energy processing machine. As Michael Marshall summarize on NewScientist: "The latest results suggest LUCA was the result of early life's fight to survive, attempts at which turned the ocean into a global genetic swap shop for hundreds of millions of years. Cells struggling to survive on their own exchanged useful parts with each other without competition - effectively creating a global mega-organism. [...] In order to cope, the early cells must have shared their genes and proteins with each other. New and useful molecules would have been passed from cell to cell without competition, and eventually gone global. [...] It was more important to keep the living system in place than to compete with other systems, says Caetano-Anoll├ęs. He says the free exchange and lack of competition mean this living primordial ocean essentially functioned as a single mega-organism".
So, Christmas is coming, add a chair for LUCA!

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