Lateral transfer climbs up the tree

Though researchers now generally agree that horizontal gene transfer is relatively common among simple organisms like bacteria, they have continued to assume that it remained relatively rare among complex organisms like plants and animals.

“The thinking has been that there is very little horizontal gene transfer among plants and animals except for a few big, ancient events and maybe the occasional transfer of a single gene here or there,” Slot said. “Our discovery suggests that the horizontal transfer of gene clusters may have been a big player not only in the evolution of bacteria but also in more complex organisms.”

Discovery of Jumping Gene Cluster Tangles Tree of Life

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3 responses to “Lateral transfer climbs up the tree

  1. I’ve wondered about HGT. Has there ever been a documented, even if artificial, example of HGT occurring between two radically different organisms? I mean radical on the order of, say.. from a bread mold to a human or vice versa.

    Further, is there a way to tell with certainty that one or another gene or group of genes was transferred by HGT? A hypothetical example: Lets say you have 2 descent lines, A and B, that diverged 2 million years ago. Both A and B have gene/gene-group X in common between them. But B acquired the gene roughly 1.8mya, and A acquired the gene originally through an HGT event 500kya, and it took hold.

    Could we tell the difference? Or would the assumption just be X was possessed by the LCA between them 2mya?

  2. I’ve wondered about HGT. Has there ever been a documented, even if artificial, example of HGT occurring between two radically different organisms? I mean radical on the order of, say.. from a bread mold to a human or vice versa.

    There are tons of examples of artificial HGT – that’s what genetic engineering is all about. Scientists just exploit mechanisms of HGT that exist within cells.

    Further, is there a way to tell with certainty that one or another gene or group of genes was transferred by HGT? A hypothetical example: Lets say you have 2 descent lines, A and B, that diverged 2 million years ago. Both A and B have gene/gene-group X in common between them. But B acquired the gene roughly 1.8mya, and A acquired the gene originally through an HGT event 500kya, and it took hold.

    Certainty is not achievable, but HGT events usually leave a trail of bread crumbs. For example, with A, the sequence of gene may be more closely related with the sequence of more distantly related species than nearby cousins, the GC content of the gene might be different that the surrounding genome, and the gene might be in a different gene neighborhood that it is in A. However, if we are talking about very ancient HGT events, these clues might not help and the HGT event would be overlooked.

  3. Actually, it looks like I asked just in time. Found this over at Panspermia.org:
    http://www.eurekalert.org/pub_releases/2011-02/nu-gaa021111.php

    If a human cell and a bacterial cell met at a speed-dating event, they would never be expected to exchange phone numbers, much less genetic material. In more scientific terms, a direct transfer of DNA has never been recorded from humans to bacteria.

    Until now. Northwestern Medicine researchers have discovered the first evidence of a human DNA fragment in a bacterial genome – in this case, Neisseria gonorrhoeae, the bacterium that causes gonorrhea. Further research showed the gene transfer appears to be a recent evolutionary event.

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