Talk:Nucleosome

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Contents 1 Merge Nucleosome core particle with this one? 2 Illustration? 3 Recursive definition 4 Possible image

[edit] Merge Nucleosome core particle with this one?

I propose that we replace the small and redundant information found in the core particle page with a redirect to this page. Any comments? Would anybody oppose if I added a redirect from that page to this one? -RockyRaccoon 03:36, 3 April 2006 (UTC)

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What's a "core nucleosome"? Please define!

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"A chain of nucleosomes can be arranged in a 30-nm-fiber, a compacted structure (once thought to be a helical solenoid, but now considered likely to exist as a zig-zag structure in vivo)"

It seems to me that the idea that 30-nm-fiber is not a solenoid but a zig-zag could be very controversial. Study books, such as Genes VIII by Benjamin Lewin, depict the structure as a solenoid as late as 2003. What source is used to make a claim for zig-zag structure? --EnSamulili 16:22, 15 Mar 2005 (UTC)

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This should serve as a reference. I'll do it myself when I have time, unless someone else beats me to it. -Jenks

"Rydberg B; Holley WR; Mian IS; Chatterjee A. Chromatin conformation in living cells: support for a zig-zag model of the 30 nm chromatin fibre. Journal of Molecular Biology, 1998 Nov 20, 284(1):71-84.

   A new method was used to probe the conformation of chromatin in living
   mammalian cells. The method employs ionizing radiation and is based on the
   concept that such radiation induces correlated breaks in DNA strands that are
   in spatial proximity. Human dermal fibroblasts in G0 phase of the cell cycle
   and Chinese hamster ovary cells in mitosis were irradiated by X-rays or
   accelerated ions. Following lysis of the cells, DNA fragments induced by
   correlated breaks were end-labeled and separated according to size on
   denaturing polyacrylamide gels. A characteristic peak was obtained for a
   fragment size of 78 bases, which is the size that corresponds to one turn of
   DNA around the nucleosome. Additional peaks between 175 and 450 bases reflect
   the relative position of nearest-neighbor nucleosomes. Theoretical
   calculations that simulate the indirect and direct effect of radiation on DNA
   demonstrate that the fragment size distributions are closely related to the
   chromatin structure model used. Comparison of the experimental data with
   theoretical results support a zig-zag model of the chromatin fiber rather
   than a simple helical model. Thus, radiation-induced damage analysis can
   provide information on chromatin structure in the living cell."

some links:

   http://nano.chem.emory.edu/~dlm/chromatin.html
   http://www.lbl.gov/lifesciences/NSCORT/pages/publications/abstracts1.html
   http://www.lorentz.leidenuniv.nl/~schiessel/two_angle.html   (good pictures)
   http://www.biophysj.org/cgi/content/full/82/6/2847
   http://www.mpip-mainz.mpg.de/~heli/langowski.pdf

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1998 is pretty old for molecular biology. "Molecular Biology" By Weaver (2005), still explains in great detail (more than the other proposed structures) the 30nm fiber taking a solenoid shape. However, he does note that a zig-zag pattern, a superbead pattern, and no special pattern have also been proposed. Unless there is clear evidence (which I haven't seen in any so far) that the solenoid is now generally rejected, the article shouldn't imply it, or that the zig-zag pattern is likely to be it. The only thing that everyone can agree on is that the structure is disputed. --jag123 02:03, 28 Apr 2005 (UTC)

[edit] Illustration?

I created an illustration a while back when this was on the now-nonexistent Image Recreation Requests page, and just got around to finishing it up and uploading it. Is it irrelevant now, or should it be added? (Note: The new version is on the commons, I'm working on getting the old one deleted. For now, link)

--The Human Spellchecker 04:41, 3 February 2006 (UTC)

Thank you for your effort. I'm sorry to say, however, that nucleosome doesn't look quite like that (the old, deleted picture was also in error). -EnSamulili 20:15, 4 February 2006 (UTC)

I had based it off of the image that was removed because of copyright issues, one similar to this one. It's a simplified view, but it helps get a basic idea of what a nucleosome looks like. --The Human Spellchecker 21:53, 4 February 2006 (UTC)

I think something like this should be included to give a vague idea of what this thing looks like. I could modify it - i.e. duplicate it and make a chain, make the bubbles little twisty proteins, make it 1.6 revolutions, etc. --The Human Spellchecker 23:03, 17 February 2006 (UTC)

[edit] Recursive definition

A nucleosome is the fundamental repeating subunit of eukaryotic DNA, and is made up of DNA and...

How can a nucleosume be a subunit of something which it comprises? Do you mean eukaryotic chromatin? 129.7.56.177 05:42, 12 February 2006 (UTC)

Changed it. -EnSamulili 14:43, 12 February 2006 (UTC)

[edit] Possible image

User:TimVickers produced the following image which I nominated for deletion last week because it wasn't being used anywhere. User:Deryck Chan was nice enough to look through my nominations at my request and thought that this one was worth saving, and might be useful on this article. ~ BigrTex 17:10, 5 February 2007 (UTC)