Viral Missing Link Caught on Film

Viral Missing Link Caught on Film | WIRED

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A virus so large and strange that it’s redefined the very concept of a virus has been photographed for the first time. It’s even weirder than expected.

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The new structural finds, along with previous genetic and morphological work, confirm that mimivirus is an odd mix of genes and parts found in viruses, bacteria and even eukaryotes, the organisms that sequester their DNA in a nucleus, write the researchers.

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What does this mean, then, for the mimivirus’ official status, which has caused some researchers to call for a redefinition of virus?

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Perhaps that’s the wrong question to ask. Eugene Koonin, a National Center for Biotechnology Information researcher who reported last year that, in another viral first, mimiviruses can actually become infected by other viruses, was nonplused by arguments over mimivirus classification.

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They’re part of the biosphere, and that’s more than enough for me, he said at the time.

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What a remarkable thing! Fascinating.Not sure that I'd call it a missing link, what is it supposed to be a missing link between? It strikes me more as a new and, perhaps revealing, form of pseudo-life.

Yeah, I dunno about that one. I think its just one of those catch phrases now-a-days. From the article:

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It took 11 years for the mimivirus to be officially defined as a virus, though the definition didn’t quite fit. In addition to its enormous size, many of its genes came from bacteria. Some researchers called it a missing link that blurred the boundaries between viruses and living cells, between living and dead.

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How do scientists determine that a particular gene, such as those found in the mimivirus in this case, came from a bacterium? Do bacterial genes (or at least some of them) have specific signatures that identify them as being of bacterial origin? And the same question applies to "viral genes" and "eukaryotic genes". What are these specific signatures? Any experts here have the answer to this?

They mean that they have sequences (actually I think they mean proteins, presumed to have been coded by genes - I don't believe a gene sequence has been established) that have previously only been found in these groups.