Discovery of giant viruses sparks debate over tree of life according to : Digital Journal

More about giant virus, Klosneuvirus, Tree of Life, mimivirus, Genomes giant virus Klosneuvirus Tree of Life mimivirus Genomes "It's crystal clear that these giant viruses belong to a group of viruses that includes much smaller ones," he says. "I'm quite confident that the current record of the genome size of giant viruses will be broken," he says. By By Karen Graham 21 mins ago in Science The discovery of some new giant viruses in an Austrian waste-water treatment plant has added new fuel to the debate surrounding the origins of viruses. Finding a giant virus genome took the project into a completely new and unexpected, yet very exciting direction."




Giant viruses are characterized by disproportionately large genomes and virions that house the viruses' genetic material. Scientists have been fascinated by giant viruses since 2003, when a group of French biologists led by Didier Raoult discovered the Mimiviruses. Another—a scenario championed by Koonin—presents the idea that giant viruses arose from smaller viruses. And Koonin believes there are more giant viruses waiting to be discovered in metagenomic data. One posits that giant viruses evolved from an ancient cell, perhaps one from an extinct fourth domain of cellular life.

New giant viruses suggest their genomes expanded like an accordion

Combined, the new viruses add2,500 additional gene families to the ones previously found in giant viruses. The giant viruses make a correspondingly giant coat, one that may have a lot more flexibility in terms of how much material it can hold. Only three of those appear to date back to the ancestor of all giant viruses. And a careful analysis of their genes suggests they, and all other giant viruses, have been put together through relatively recent evolution. This search put together three additional giant virus genomes, belonging to Catovirus, Hokovirus, and Indivirus.


collected by :Sandra Alex
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