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Comment: Re:I looked at two phyl. trees presented there (Score 2) 124

by De_Boswachter (#35609028) Attached to: DNA Analysis Hints At a Fourth Domain of Life

Not underwhelmed here. It really is just a hint, as the title says. I spent a few minutes looking at it. At first sight, they could have been new sequences representing life forms from either of the three existing domains, or viruses. And, indeed, in the discussion section, they are careful with their explanations. The last two of four are deemed the most plausible.

"[...] A third possibility is that the genes from novel subfamilies come from novel heretofore uncharacterized viruses. Given that the known viral world represents but a small fraction of the total extant diversity, and given some of the unexpected discoveries coming from viral genomics recently, this is entirely possible. For example, viruses have been characterized with markedly larger genomes that contain not only more genes, but genes previously found only in cellular organisms. In some cases, the viral forms of these genes appear to be phylogenetically novel compared to those in cellular organisms.

[Explanation 4:] It has not escaped our notice that the characteristics of these novel sequences are consistent with the possibility that they come from a new (i.e., fourth) major branch of cellular organisms on the tree of life. That is, their phylogenetic novelty could indicate phylogenetic novelty of the organisms from which they come. Clearly, confirmation or refutation of this possibility requires follow-up studies such as determining what is the source of these novel, deeply branching sequences (e.g., cellular organisms or viruses). Then, depending on the answers obtained, more targeted metagenomics or single-cell studies may help determine whether the novelty extends to all genes in the genome or is just seen for a few gene families."

Most likely, these new sequences are from viruses, but I can't suppress hoping that there really are more domains out there.

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