Cell biology Genomics

Nuclear Membrane Not Just a Bubble

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Phys.Org has a new summary about a new finding regarding heterochromatin repair in the nucleus which involves the nuclear membrane. In their discussion, they make some interesting points:

Previously, the nuclear membrane was thought to be mostly just a protective bubble around the nuclear material, with pores acting as channels to transport molecules in and out. But in a study published on October 26 in Nature Cell Biology, a research team led by Irene Chiolo documents how broken strands of a portion of DNA known as heterochromatin are dragged to the nuclear membrane for repair.

The reason why we don’t experience thousands of cancers every day in our body is because we have incredibly efficient molecular mechanisms that repair the frequent damages occurring in our DNA. But those that work in heterochromatin are quite extraordinary.

So, let’s reflect here a little bit. If the repair mechanism is not in place, an organism will die of cancer, and leave no offspring. So, how did this system “evolve” in the first place? Actually, isn’t this more like IC, “irreducible complexity”?

The bacterial cell, IIRC, has no nucleus, and has a much smaller genome which is circular. So, to deal with a larger genome, you need something to tidy the chromosomes up. So you break them into smaller units, and come up with a way of condensing the nucleotide string of bases, which is the job of chromatin. But now, if chromatin fails, then what?

Lo and behold: a repair mechanism that utilizes the nuclear membrane to segregate the chromsomes from getting stuck together with other portions of the cell, and then you use to nuclear membrane for repair so that until the heterochromatin is repaired, it won’t get gummed up with something else and cause greater problems.

And, finally:

Working with the fruit fly Drosophila melanogaster, the team observed that breaks in heterochromatin are repaired after damaged sequences move away from the rest of the chromosome to the inner wall of the nuclear membrane. There, a trio of proteins mends the break in a safe environment, where it cannot accidentally get tangled up with incorrect chromosomes.

I tell you, it functions like a machine! Oops. I’m sorry. We know it looks designed, and acts designed, but everything came about in a random fashion. As Dawkins tells us to keep doing, I have to repeat to myself, “It isn’t designed. It isn’t designed…,” or else I risk getting confused.
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More seriously, we’ve come a long way since Darwin’s time, a time when the cell was thought to be no more than “protoplasm,” some gel that filled the ovum. Egg white, if you will.

In the same way, the nuclear membrane is just a bunch of lipids that spontaneously configured themselves. You know—a bubble.

With each passing month, as techonology improves, more and more complexity is found. And, according to the strictly materialist view that underpins much of Darwinism, this is brought about by “random” mutations.

The rise of complexity is hitting the scientific community like a tidal wave; and yet it just digs in its heels and says: “No big thing. We’ve known about that for a long time.”

Here’s the abstract from Nature Cell Biology:

Heterochromatin mostly comprises repeated sequences prone to harmful ectopic recombination during double-strand break (DSB) repair. In Drosophila cells, ‘safe’ homologous recombination (HR) repair of heterochromatic breaks relies on a specialized pathway that relocalizes damaged sequences away from the heterochromatin domain before strand invasion. Here we show that heterochromatic DSBs move to the nuclear periphery to continue HR repair. Relocalization depends on nuclear pores and inner nuclear membrane proteins (INMPs) that anchor repair sites to the nuclear periphery through the Smc5/6-interacting proteins STUbL/RENi. Both the initial block to HR progression inside the heterochromatin domain, and the targeting of repair sites to the nuclear periphery, rely on SUMO and SUMO E3 ligases. This study reveals a critical role for SUMOylation in the spatial and temporal regulation of HR repair in heterochromatin, and identifies the nuclear periphery as a specialized site for heterochromatin repair in a multicellular eukaryote.

10 Replies to “Nuclear Membrane Not Just a Bubble

  1. 1
    EvilSnack says:

    The bacterial cell, IIRC, is much larger, has no nucleus, and has a much smaller genome which is circular.

    Are you sure about this? I had been led to believe that bacterial cells are generally smaller than eukaryotic cells; one source affirming this is here.

    Made the corrections. Thanks. Pav.

  2. 2
    tjguy says:

    As DAWKINS tells us to keep doing, I have to repeat to myself, “It isn’t designed. It isn’t designed…,” or else I risk getting confused.

    I think it was Francis Crick who said that.

    But, at any rate, the reason for that statement is clear wherever you look in nature.

    The reason why we don’t experience thousands of cancers every day in our body is because we have incredibly efficient molecular mechanisms that repair the frequent damages occurring in our DNA. But those that work in heterochromatin are quite extraordinary.

    So, let’s reflect here a little bit. If the repair mechanism is not in place, an organism will die of cancer, and leave no offspring. So, how did this system “evolve” in the first place?

    It just did, OK? We’re here, aren’t we?

    Geez! What more proof do you need?!

    This just goes to show again, that it is not really a matter of evidence, but of worldview. In the end, there is NO evidence that will ever convince most Materialists they are wrong! Without this repair mechanism working from the very beginning, life would not have stood a chance even if it amino acids formed and somehow self-arranged themselves in code form enabling chemicals to come to life like Frosty the Snowman.

  3. 3
    Andre says:

    Wow this paper highlights exactly what I’ve been saying.

  4. 4
    Andre says:

    This article is absolutely brilliant, it highlights the points I’ve been trying to bring across for some time now about the engineering principles applied in living systems.

    First though, from an engineering point of view what do we recognise? What are engineering principles and are they in anyway represented in Living systems? I note them below not in any logical order.

    1.) Maintainability
    2.) Integrity
    3.) Systems
    4.) Processes
    5.) Components
    6.) Materials
    7.) Redundancy
    8.) Trade-Offs
    9.) Function
    10.) Construction
    11.) Procedures
    12 ) Pay-Offs
    13.) Creativity
    14.) Criteria
    15.) Solutions

    I say based on our observations and our understanding of engineering, that Living systems meet the criteria 100% of being engineered. We recognize it empirically.

  5. 5
    Andre says:

    And for the Random lucky accident crowd (Don’t want to call it Darwinism because Prof Moran might pop a vein) things are just getting worse…..

    http://phys.org/news/2015-10-c......html#nRlv

    I will say it again….

    Multiple Integrity checks
    Multiple repair mechanisms

    How does random have a chance against all these checks and balances when there is so much redundancy in the system? There is no chance…..

    What is clear is this, life ain’t easy if it needs this many repair mechanisms to keep living systems going then the idea that some amino acids formed somewhere in a warm little pond and the first replicator was born is as dead as disco.

  6. 6
    Mapou says:

    hrun0815,

    Man, get your head out of your rear end. This thread is about science, not religion.

  7. 7
    Peter says:

    Good luck finding life on other planets. I guess it take a little more than water.

  8. 8
    Box says:

    PaV: I tell you, it functions like a machine!

    Does it? Is what we see machine-like? Something like a watch perhaps? It seems to me that we see is constant improvisation and implies orchestration from a higher level. What instructs these particles what to do and where to go?

  9. 9
    bornagain says:

    Did not Dr. Moran claim not too long ago that repeated sequences in DNA were proof that large fractions of the genome was junk DNA?

    If so, why is this found?

    Excerpt: heterochromatin, which is mostly composed of repeated DNA sequences, has long been ignored as “junk DNA.”
    “Scientists are now starting to pay a lot of attention to this mysterious component of the genome,” said Chiolo, assistant professor at the USC Dornsife College of Letters, Arts and Sciences. “Heterochromatin is not only essential for chromosome maintenance during cell division; it also poses specific threats to genome stability. Heterochromatin is potentially one of the most powerful driving forces for cancer formation, but it is the ‘dark matter’ of the genome. We are just beginning to unravel how repair works here.”
    http://m.phys.org/news/2015-10.....k-dna.html

  10. 10
    Alicia Cartelli says:

    “Heterochromatin is potentially one of the most powerful driving forces for cancer formation”

    Why does my heterochromatin sound like a ticking time bomb?
    How can I get a hold of the great designer to thank him for these ticking time bombs?

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