Brent over at Unscrewing The Inscrutable has an entry up titled ‘MimiVirus’ Bolsters Abiogenesis Evidence that points to recent research done on a monster virus first discovered in 1992 that appears to provide supporting evidence theories on how life began on Earth:
Mimi was discovered in 1992, nestling inside an amoeba found inside a cooling tower in Bradford, UK, that was being investigated as the source of an influenza outbreak. Later research showed that it was a real monster, measuring about 800 nanometres across, more than four times as big as a smallpox virus. The new study shows that its genome contains 1.2 million bases, which is more than many bacteria contain and makes it several times bigger than the largest DNA viruses. The bases make up 1,260 genes, which makes it as complex as some bacteria, the scientists say.
What’s more, viral DNA often contains lots of ‘junk’ sequences, genetic material that does not seem to serve any useful function. Mimi, on the other hand, is lean and mean: more than 90% of its DNA does something specific.
As Mimi carries some genes involved with replication, this could have helped it to spread faster than other viruses, explains Anne Bridgen, a virologist from the University of Ulster, Northern Ireland. “I’ve never heard of viruses encoding something like this,” she says.
All cellular life is grouped into three basic kingdoms—bacteria, archaea, and eukarya—but with the discovery of MimiVirus some scientists are suggesting there should be a fourth designation:
Bacteria are the simplest branch, because they lack a nucleus to gather their genetic material together. Archaea are very similar, but are thought to have evolved separately because of their unusual cell membranes. Every other living thing is a eukaryote, that is, an organism that groups its genetic material into a nucleus inside its cells. But Mimi carries seven genes that are common to all cellular life, putting it on a par with the other life-forms, says Raoult.
So how does this tie into Abiogenesis?
Some scientists have speculated that eukaryotes originally evolved from collaboration between a virus and a bacterium. Bacteria could have supplied the ribosomes, the protein factories of the cell, and viruses might have injected their genetic material into a proto-nucleus. One weakness of the theory is that viruses generally lack some of the key genes seen in eukaryotes. But Mimi’s complex genome includes these, lending support to the idea, says Raoult.
This is a major discovery that opens whole new pathways for researchers to follow.