Wednesday, October 29, 2008

'Cheshire Cat' Escape Strategy

The study of one of the most abundant unicellular eukaryotes seems to show that sex was invented to escape viral infections. In their normal haploid form-
Emiliania huxleyi produce mineral scales and form gigantic populations that are visible from space. But when attacked by marine viruses, they transform into haploid cells which only contain a single chromosome (N). These new, non-calcifying, highly motile cells are totally invisible to viruses (and undetectable on satellite photos) so that the species can live in peace to await safer times.
Primitive single-celled predecessors to the Earth's flora and fauna changed their form by separating their 2 chromosomes to become motile and to eliminate binding points used by invading viruses. When the viral onslaught abated they recombined into their normal two-chromosome form. The fact that the process accelerated genetic variations and precipitated evolution to more complex forms was just an unavoidable by-product.

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