Talk:Chimera (genetics)

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[edit] article title

Why is this article called "Chimera (genetics)" and others are "(virus)" and "(plant"). Surely this should be "(animal)", or indeed fuse all together. There is nothing more genetic about this article than the other two. path 21 July 2007

[edit] Behavioral Genetics

Anyone have any interesting research done on human chimeras in terms of behavioral genetics? Seemingly there has been stated gender role confusion so I'm very interested in this since fraternal twins naturally are male and female, and in this case, there is one "human" outcome. Make s me feel like i'm in the X-men movie saying "human" :) --Cyberman 00:34, 8 October 2005 (UTC)


[edit] Transsexuals

Is it worthwhile mentioning the possibility, which I believe has been raised numerous times, of transsexuals, or people with gender identity issues, being this way due to being biological chimeras where the brain is physically a different gender from the sexual organs?

A chimera is specifically an individual with genetic material from different zygotes. That is, it is exclusively to do with the genotype. It says nothing about the phenotype. Chevin 09:01, 1 May 2006 (UTC)
I disagree, Chevin. If chimerism doesn't affect phenotype, then that calls into question the part of the article stating that "such persons sometimes also have patchy skin, hair, or eye pigmentation (heterochromia)." I've heard of a particular case in which a child suffering from chimerism was male on one side of the body and female on the other, with separate skin tones corresponding to the two sexes. In this child's case, chimerism was clearly affecting not just the genetic material but the expression of those genes, as well. This Wikipedia article also mentions the creation of a chicken with a quail's brain. If this is possible, then it is certainly possible for a person with male genitalia to have a female brain, or vice versa. Nrclptkrkr41 03:44, 7 July 2006 (UTC)
True, but those are rare chimeras, conglomerations of two sexes. It's then that the phenotype is affected. I was looking for an article here about human chimeras, like the kind who would come up negative on a paternity/maternity test even if they are actually the father/mother. I mean, people who actually have 2 sets of DNA in their bodies. My friend's sister is like that. There was a case where a mother who applied for welfare and she was hauled into court because since she was a chimera, her maternity test came out negative. Medically speaking, a transsexual is not a chimera. Transsexuality is different from chimerism. It involves a hypothalamus that resembles the opposite sex. A chimera has 2 sets of DNA, while that is not what transsexuality is defined as. Granted, there may be some transsexuals who are genetic chimeras, but that has nothing to do with the fact that they are transsexuals. Plus, it hasn't been proven that transsexuality is genetic in the first place. So chimerism is out of the question. One is born transsexual, yes, but if the condition was genetic, then transsexuality would occur more than once in the family and there would be a gene.
Plus, since the transsexual is not a combination of a male and female, but rather, one gender stuck in the opposite gender's body, then the transsexual is not a "hybrid" or "chimera". By trying to call a transsexual a "chimera" just because he/she is of their sexuality, then that would be calling said transsexual a "mutant", rather than a "chimera". ForestAngel (talk) 05:18, 15 January 2008 (UTC)

[edit] Wikipedians who complain about stuff but never give it a title

There's an article in today's New Scientist about this. The comment at the top of the page:

Whoever wrote the following is seriously confused. To begin with, a hybrid is NOT a chimera. Species chimeras contain the cells of two or more different species of animal. Species hybrids have cells that contain nuclei that contain 2 sets of chromsomes, each from a different species. Most of the animals on the list below are hybrids, not chimeras. The one exception, the geek, is neither a hybrid nor a chimera but a type of human. Crosses between sheep and goats supposedly die in utero which, if correct, means that hybrids are not possible. It is possible to make a geep (but not a geek) by combining the embryos of sheep and goat and implanting the chimeric embryo into a host female. The resulting animal has goat cells and sheep cells combined together to make a single chimeric animal. But the goat cells remain goat cells and the sheep cells remain sheep cells. They do not fuse together to make hybrid cells.

... appears to be correct. I would like to replace the article with that at Talk:Chimera (animal) (temp)

I am not a biologist, but I will be bold and do so anyway in a day or two, if there are no objections. Evercat 23:37, 13 Nov 2003 (UTC)

I think I'm right though, ie: [1] [2] [3] [4] - last one goes into detail on the surgical creation of chimeras...

So I may just do the change tonight after all. Evercat 00:42, 14 Nov 2003 (UTC)

Done. This comment moved from the temp page:

Yes. A great relief to read this. I never know what to do about fundamentally misinformed articles. This is a very modest and discreet way to go about it. Good information. User:Wetman

[edit] Bone Marrow/Stem Cell Transplants

People who undergo allogenic (as opposed to autologous) bone marrow or stem cell transplants also exhibit chimerism, due to their having two distinct DNAs in their bodies.

[edit] Clarification needed?

Part of this article reads:

Chimeras have either 4 parents (2 fertilized eggs or early embryos are fused together) or 3 parents (a fertilized egg is fused with an unfertilized egg or a fertilized egg is fused with an extra sperm).

What about cases when the two embryos come from the same two parents? (Non-identical twins). And is it possible to create a chimera from more than 2 normal embryos?

[edit] Allophene

I think we need to do a distinction between allphene and chimera. An allophen is formed from the fusion of 2 (or more) zygotes/blastocysts. The term chimera is more general and can also apply when one put ES cells in the inner cell mass. Sucrine 19:07, 7 March 2006 (UTC)

Also we need a list of famous Chimera's. Start the list with David Bowie!!!

David Bowie is not a chimera, at least if that's a reference to his eyes. He has a paralyzed pupil, which doesn't contract so it looks like it's a different color.

[edit] Occurence Rate

Is there any known occurence rate for human chimeras? Most references simply say there are only a handful of known cases. WizardofOskemen 22:48, 6 November 2006 (UTC)

There are a handful of confirmed cases. No one knows how many chimeras there are in the world who haven't been identified. The one's who have been identified only know so because they took DNA tests and karyotyping. There may be thousands, maybe millions of chimeras in the world that don't know it, because human chimeras (those who aren't male/female chimeras) don't look any different than anyone else. ForestAngel (talk) 05:21, 15 January 2008 (UTC)

[edit] Chimerism and immunity.

After reading this article,I must admit that I was quite surprised! And alot of questions came to my mind. Most of those questions are of metaphysical implications, so I'm going to spare you that... But some others are on biological implications and It would be nice if someone can answer them, and maybe they might also be worth to add to the main article?

  • Are there any studies about chimeras and autoimmunity?

It would only be logical for them to suffer from it more frequently than normal... but the article also says that they are more receptive of donors organs... and that also makes sense...

  • What is the extent of the "hybridization" of the body? (I couldn't find a better word than hybridization for this)

I mean is it possible to have a brain composed of both types of cells without disticntions? or maybe just large areas together? like left and right hemisphere? or maybe organs are usually issued from only one type of cells? Gaaboot 17:40, 1 December 2006 (UTC)

[edit] Next

Michael Crichton's new book, Next, mentions chimeras several times, along the lines of failed paternity tests due to a chimera father. Perhaps this should be added to the page under popular culture. —The preceding unsigned comment was added by 24.225.21.231 (talk) 03:29, 7 December 2006 (UTC).

[edit] Virus

The proposal is to insert human DNA into a cow's egg which has had its genetic material removed and then create an embryo by the same technique that produced Dolly the Sheep.

Technically speaking, does this mean Humans are now officially classifiable as a virus?--Zerothis 16:01, 14 June 2007 (UTC)

[edit] Is this really necessary?

It is important to realize that studies like these are being conducted in order to identify a cheap, ethical source of human embryonic stem-cells to study, from which to develop the medical cures of the future. Because of the high therapeutic potential of human embryonic stem cells and the American moratorium on using discarded embryos from in vitro fertilization clinics as well as other concerns about using human embryos directly for research, scientists are trying to find ways to find alternative paths of research.

I am as big a fan of safe and responsible exploration of stem-cell research as the next person, but does this tenuously relevant diatribe really need to be in this article. WookMuff 23:52, 8 November 2007 (UTC)

[edit] Tetragametic chimera section

This whole section needs references. The examples given as manifestations of chimerism that could go undetected - "hitchhikers thumb and one normal thumb, differential hair growth on opposite sides of the body" - where do these examples come from? They seem highly unlikely as manifestations of chimerism. If these are real examples, fine. But they sound like guesses - the lack of info in the rest of the article about the extent of the 'foreign' tissue, its incorporation into the body developmentally, the point at which it differentiates, or the ratio of the two types of cells in the body seems to suggest not much is known about it. I would've thought that chimerism would result in some different tissues but not anything like hair follicles on one side of the body only or one different thumb. You can envisage how those things might result from chimerism, but they don't seem the most likely example. What next, a mole on one cheek? Why not use examples from the known cases of the women, ie tissues sampled for the DNA tests? Developmental asymmetry is common in response to environmental stresses and the implications of asymmetry much studied. Some bits of this article seem to be suggesting that asymmetry is a feature of chimerism - this may or may not be true, but if it is going to be suggested more evidence should be given. —Preceding unsigned comment added by 202.36.134.22 (talk) 10:32, 11 December 2007 (UTC)

[edit] Image

The image of the male tortoiseshell cat should probably not be included on this article without qualification that not all male tortoiseshell cats are chimeras, but rather they can also be (and I suspect more likely) the result of klinefelter's syndrome and therefore x-inactivation. Are there no good photos of known chimeras freely available? --Rkitko (talk) 03:29, 22 January 2008 (UTC)

I removed the image as I took the photograph and it's a female cat. Also I imagine that a better image can be found that isn't of a severely anorexic cat with jaundice. SabarCont 08:28, 24 February 2008 (UTC)

[edit] Merge with Parahuman?

Merge tags have been added to Chimera (genetics) and Parahuman by an anon IP, but no discussion has been started. So I'll start it. No. Do not merge. Clearly separate topics. I will remove the tags unless anyone objects within 24 hours. Snalwibma (talk) 10:37, 29 February 2008 (UTC)

Definately not. There is a clear difference between the two, and only a small section of Chimera (genetics) has to do with parahuman. pacodataco8 (talk) 10:17 3 March 2008 (CST)

OK - I have removed the tags. It was tagged by an anon IP who has not apparently been back since, so that's the end of it. Snalwibma (talk) 17:31, 3 March 2008 (UTC)

[edit] Henrietta Lacks

The Henrietta Lacks article links here, but the HeLa cell line doesn't appear to match any of the definitions of chimera in this article, being a blend of human and HPV. This really isn't my expertise by a long shot, so this is a fire-and-forget comment. Just thought someone here should know in case they know how to resolve this discrepancy. –BozoTheScary (talk) 01:56, 26 March 2008 (UTC)

[edit] Jigsaw Analogy

While I started to read this article I found this statement: "An analogy is two jigsaw puzzles cut using an identical cutter, but with different pictures. A single puzzle can be made out of the mis-matched parts, but the completed puzzle will show parts of both pictures". Now, my question is: Is that sentence really necessary? It feels like it doesn't add anything informative to the introduction of the article, like it's totally out of place and has nothing to do with science. Analogies are good to understand complex subjects, but this one really puzzles me. Thanks. --Dhcp 03:07, 14 April 2008 (UTC)