Talk:Barr body

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re-titling (X-inactivation)

I see the benefit of merging the Xist discussion with this article, especially due to its stub nature. However, I'm wondering if 'Barr body' is still the best title for this article. The discussion of the mechanism, including the role of Xist has removed the discussion to a more general consideration of the role X-inactivation plays, whereas the Barr Body is the result of this process. The merging of the Xist article will further exaggerate this effect. I am wondering if the re-titling of the article, with the addition of more substructure, (ie. Separating the Barr Body itself, the mechanism, and the mosaic effects of X-inactivation) may make more sense.--JamesGlover 00:23, 24 Jun 2005 (UTC)

I agree, and suggest that the bulk of this page be moved to X-inactivation, and that X-inactivation stop being used as a re-direct to the Lyon hypothesis

Sir1 11:40, 17 February 2006 (UTC)[reply]

Cleanup

Total Revision made, all references now in Wiki Quality Standards. Dr. F.C. Turner - [USERPAGE|USERTALK] - 08:44, 30 December 2009 (UTC)[reply]

Mitosis

How does the Barr body replicate? That is, how does the inactivated chromosome nonetheless duplicate itself, and how does it preserve/propagate the inactivation status? Cesiumfrog (talk) 22:02, 26 January 2019 (UTC)[reply]

@Cesiumfrog: Yes, replication is just like the other X or any other chromosome. I think after replication the same X becomes inactive again. Reply to this with {{re|irtapil}} or {{ping|irtapil}} if you would like me to help you find more info. Irtapil (talk) 06:20, 4 June 2020 (UTC)[reply]

@Irtapil: How can it be duplicated "just like any other chromosome" if its chemistry and configuration are altered specifically in a manner that otherwise prevents transcription? Afterward, what is the mechanism that ensures the same X stays inactivated (and the other X never becomes inactivated instead) in both daughter copies?

To explain the most obvious observable functions regarding the article topic, e.g. in the coat patterns of calico cats, you need two things: random deactivation of all but exactly one X chromosome at a particular stage of embryo development, and preservation of the choice throughout all subsequent cell divisions. I think the article should cover both of these things, but currently it only discusses the initial deactivation and has yet to discuss how the selection is propagated in mitosis. Cesiumfrog (talk) 23:13, 4 June 2020 (UTC)[reply]

@Cesiumfrog: First, in answer to "How can it be duplicated "just like any other chromosome" if its chemistry and configuration are altered specifically in a manner that otherwise prevents transcription?"

Chromosome replication before cell division, is a completely different process to transcription. (the following all just applies to animals, viruses are weird.) Replicating a chromosome makes a DNA copy of a DNA chromosome. Transcription, which is inhibited from the Barr body, makes an mRNA copy of the DNA. RNA is is a slightly different chemical to DNA, and the mRNA has a very different function to the chromosome. Reading the mRNA page will probably give some useful background. Also try mitosis and meosis.

I'll try later to find some refs for how same X ends up deactivated after cell division. (My wild guess is methylation.) A related topic is epigenetics, though that deals with preservation of transcription inhibition between parent and offspring, not within an individual.

Irtapil (talk) 01:39, 5 June 2020 (UTC)[reply]

readable and accurate terminology for humans

Most instances of "men" or "women" in this were inaccurate, e.g. not all XXY people are men, but expanding each to "men, women, girls, boys, or intersex people" makes the article unreadable, just say "people" then readers can click the links for more details. Irtapil (talk) 04:49, 4 June 2020 (UTC)[reply]

rough guide to simplest options of phrasing =

anything where we can link a medical article = "people"
XY or one X chromosome = "people", "mostly men", "such as most men", or "including most female mammals".
XX or two X chromosomes = "people", "mostly women", "such as most women", or "including most female mammals".

Irtapil (talk) 04:57, 4 June 2020 (UTC)[reply]

ZW sex determination

Is it actually called a bar body when it's a Z chromosome? does it even happen with Z chromosomes? Irtapil (talk) 04:25, 4 June 2020 (UTC)[reply]

old version: "A Barr body (named after discoverer Murray Barr)^[1] is the inactive X chromosome in a female somatic cell,^[2] rendered inactive in a process called lyonization, in those species in which sex is determined by the presence of the Y (including humans) or W chromosome rather than the diploidy of the X."

^ Barr, M. L.; Bertram, E. G. (1949). "A Morphological Distinction between Neurones of the Male and Female, and the Behaviour of the Nucleolar Satellite during Accelerated Nucleoprotein Synthesis". Nature. 163 (4148): 676–7. doi:10.1038/163676a0. PMID 18120749.
^ Lyon, M. F. (2003). "The Lyon and the LINE hypothesis". j.semcdb. 14: 313–318. doi:10.1016/j.semcdb.2003.09.015. PMID 15015738.

removed for now. Irtapil (talk) 06:29, 4 June 2020 (UTC)[reply]

[1] Barr, M. L.; Bertram, E. G. (1949). "A Morphological Distinction between Neurones of the Male and Female, and the Behaviour of the Nucleolar Satellite during Accelerated Nucleoprotein Synthesis". Nature. 163 (4148): 676–7. doi:10.1038/163676a0. PMID 18120749.

[lyon2003-2] Lyon, M. F. (2003). "The Lyon and the LINE hypothesis". j.semcdb. 14: 313–318. doi:10.1016/j.semcdb.2003.09.015. PMID 15015738.

[1]

[2]