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Bacterium breaks all the rules. Cell structured like animal.

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From Jennifer Frazer at Scientific American:

Gemmata obscuriglobis excels at breaking rules. Like the platypus, to whom these bacteria have been compared, they possess a baffling arsenal of oddities.

Although it has been controversial, they seem to contain membrane-bound compartments. One of those compartments surrounds their DNA. That would make it, apparently, a nucleus. But bacteria are thought to be devoid of nuclei – hence the terms prokaryote (“pre-kernel”) for bacteria and archaea, and eukaryote (“true kernel”) for all nucleated life (which includes all multicellular organisms).
The eye-popping apparent commonalities don’t end there.

If that is the case, it means one of two equally astounding things must be true: either this humble bacterium, isolated from freshwater near the Maroon Dam in Queensland, Australia is the closest living relative of eukaryotes, and split from our last common ancestor with bacteria long ago. Or it has independently evolved, under similar pressures, shockingly similar solutions to the same cellular and biochemical problems, right down to the architecture of its nuclear pores. More.

Well, if Gemmata obscuriglobis is the closest living ancestor of eukaryotes, it’s odd that no one had thought so before. If not, this is a dramatic example of convergent evolution.

What the world needs now is a dose of good old-fashioned there-is-no-debate Darwinian fundamentalism, to resolve this stuff.

See also: Evolution appears to converge on goals—but in Darwinian terms, is that possible?

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7 Replies to “Bacterium breaks all the rules. Cell structured like animal.

  1. 1
    Dionisio says:

    Interesting article. Thanks.

  2. 2
    Dionisio says:

    This is the original paper this article refers to:

    Finding bacterial pores within internal cell membranes and with structural similarities to eukaryote nuclear pore complexes raises the dual possibilities of either hitherto undetected homology or stunning evolutionary convergence.

    Sagulenko E, Nouwens A, Webb RI, Green K, Yee B, Morgan G, et al. (2017) Nuclear Pore-Like Structures in a Compartmentalized Bacterium. PLoS ONE 12(2): e0169432. doi:10.1371/journal.pone.0169432

    http://journals.plos.org/ploso.....ne.0169432

  3. 3
    Dionisio says:

    This is the original paper this article refers to:

    The evolutionary implications of these results are considered, both from the perspective of common ancestry with the eukaryote nuclear pore complex, and from the viewpoint of convergent evolution.

    Sagulenko E, Nouwens A, Webb RI, Green K, Yee B, Morgan G, et al. (2017) Nuclear Pore-Like Structures in a Compartmentalized Bacterium. PLoS ONE 12(2): e0169432. doi:10.1371/journal.pone.0169432

    http://journals.plos.org/ploso.....ne.0169432

  4. 4
    Dionisio says:

    This is the original paper this article refers to:

    .

    Detailed analysis of the composition of the internal bacterial pores will no doubt enable the evolutionary origin of these structures to be definitively established.

    Sagulenko E, Nouwens A, Webb RI, Green K, Yee B, Morgan G, et al. (2017) Nuclear Pore-Like Structures in a Compartmentalized Bacterium. PLoS ONE 12(2): e0169432. doi:10.1371/journal.pone.0169432

    http://journals.plos.org/ploso.....ne.0169432

  5. 5
    Dionisio says:

    This is the original paper this article refers to:

    .

    In any case, whether homologous or analogous to components of eukaryote nuclear envelopes, the structures found here in a planctomycete bacterium pose a challenge to those current theories of the origin of eukaryotes and their cell organization depending on fusion of different cell types or endosymbiosis.

    This is so since they suggest that structures at least analogous to those found in eukaryotic nuclei can occur in a bacterium with otherwise prokaryote affinities, in the absence of any obvious endosymbiosis or inter-Domain cell fusion.

    It seems that it is not necessary for origin of analogs of characteristic eukaryote cell biology features to rely on inter-Domain cell fusion, and that endogenous origin of such features is possible.

    Sagulenko E, Nouwens A, Webb RI, Green K, Yee B, Morgan G, et al. (2017) Nuclear Pore-Like Structures in a Compartmentalized Bacterium. PLoS ONE 12(2): e0169432. doi:10.1371/journal.pone.0169432

    http://journals.plos.org/ploso.....ne.0169432

    [emphasis added]

  6. 6
    gpuccio says:

    Dionisio:

    The origin of eukaryotes seems to be one of the evolutionary fields that is more likely to be revolutionized in the next few years.

    See also:

    http://www.huffingtonpost.com/.....3f81e447b0

  7. 7
    Dionisio says:

    gpuccio,

    Yes, I think you commented on this recently.

    That’s an interesting article on a very important subject.

    Thanks.

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