Talk:Leucism
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Are leucistic animals truly albino's? Everything I've read says that leucistic animals are lighter, but not truly albino's. Such as this story http://www.wcs.org/353624/whitegiraffe about a leucistic giraffe. Suppafly 18:12, 15 September 2005 (UTC)
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[edit] Image added
I added an image showing Leucism in a Mallard duck
Wonko the Sane 19:44, 9 March 2007 (UTC)
[edit] human leucism
Is there a posibility that leucistic humans exist? My grandfather was a werry pale man who married much darker woman, and ended up with 4 sons 3 pale in different ways(one white hair and beard one pale skin)an one with dark hair and dark skin. my father was paleskinned but had blondhair and a red beard and marrried a spannish lokking woman, i to am extremly pale,what the f.. do i have?
I agree with the artical pertaining to humans. For you must understand the first human was a black man and from him came all people of color including the white man. Our leaders will not discuss this issue. It is used but rarely in humans this LEUCISM. (JK)
- There are different forms of spotting in humans, the Waardenburg syndrome and Piebaldism Kersti Nebelsiek 20:47, 1 April 2007 (UTC)
[edit] Incorrect explanation
The explanation for what leucism is in this article is incorrect. Leucism is a catch-all term for result of defects in chromatoblast differentaition and/or migration from the neural crest. This results in either the entire skin, or patches of skin, having a lack or reduction in chromatophores (the cells that make pigment). [1] Since all chromatophore types differentiate from the same precursor cell type, this can effect all colours of pigment (since, if the cell isn't there, the pigment can't be made). This differs from albinism. Albinism only effects melanin production because it is a defect in key enzymes required for the process, but the cells are still present. The reason eyes are not usually affected in leucism is because the pigment cells from the eye do not come from the neural crest. However they are affected albinos because they use the same process to make the melanin. When i get the chance this week, i'll rework the entire article to try and make it accurate. In the meantime, i'm tagging it with {{incorrect}} and {{expert}} templates. Rockpocket 18:29, 18 July 2006 (UTC)
- It is not completely true, that the eyes are not affected in Leucism. There are leucistic animals with red eyes, there are leucistic animals with blue eyes and there are leucistic animals with dark eyes - that differs because of the different genes, leucism may be due to.
- Completely albinotic animals usually have red eyes (Allel c) - but not every animal with a form of albinism is completely albinotic and therefore there are partly albinotic animals with red, blue or darker eyes. Kersti Nebelsiek 20:41, 1 April 2007 (UTC)
- For examples of leucistic Mice with red eyes, see: http://www.informatics.jax.org/searches/allele_report.cgi?markerID=MGI:104554 Kersti Nebelsiek 22:50, 10 April 2007 (UTC)
[edit] Chromatophore
To Rockpocket
I took your suggestion and looked at the Chromatophore article. It is very nice. I may do a clinically oriented article to dove tail with it when I get the chance.Snakevet2003 08:14, 10 December 2006 (UTC)
- Sounds good. By the way, I reverted your recent edit regarding the skin microenvironment. I did so because it replaced an explanation for why there is a difference (genetically speaking) with a consequence of that. Still, I think some of your content above would benefit the article, you would just need to source it. Rockpocket 08:18, 10 December 2006 (UTC)
[edit] skin microenvironment.
Research done and reported by Bechtel in his book does explain why there is a difference. The difference is not due to the melanin producing cells not arising from neural crest, in fact, some embryologists will disagree with you about the melanocytes not being of neural crest origin as some consider all of the neuroectoderm to be of neural crest origin including the portion that forms the optic cup. However, be that as it may, if melanocytes from the eye are placed in the skin, they die. The problem is not due to the different develomental origins, it is due to the microenvironment of the skin. Furthermore, as I explained the transplantation of healthy chromatophores demonstrates the problem is not due to embryologic origin, but within the skin itself. I have deleted my explanation above, because I just found that others have apparently edited it and added both false and racially oriented material to it. This vandalism I cannot tolerate. Unfortunately this is the third time I have written something for wikipedia and had it changed in such a way as to be inappropriate and offensive. I think I will not submit anything further until wikipedia allows responses to be locked and unchangable.User:snakevet2003 23:05, 10 December 2006 (UTC)
- If you can provide reliable sources for this, then by all means add it to the article. I think it would be an improvement.
- Regarding the editing of your comments above, checking the edit history it doesn't appear to me that anyone edited your comments nevermind added "racially oriented material". The only edits to it were the automatic addition of a signature by a bot [2]. Could you elaborate on what you mean and I can take action against the culprits? Rockpocket 00:44, 11 December 2006 (UTC)
[edit] Eye Colour
The pink ('red') colour for which albinos are famed is not the colour of the retina but the colour of the iris, which lacks melanin also. Even in albinos, the pupil still looks black rather than red because the inside of the eyeball is dark, irrespective of whether the retina is as black as it would normally be. This needs correcting, please, somebody, but I'm not an expert so I'm not doing it.
Sapphirine 03:12, 17 December 2006 (UTC)Sapphirine
- My understanding is that the red colour (which is actually pretty rare in human albinos) is from the blood vessels that line the retina and the iris. In the absence of a pigmented iris and a pigmented RPE, these vessels will be apparent. This give the pupil a red hue in the presence of light (everything looks black in the absence of light!) and the iris a red hue to the the light reflecting from the fundus being absorbed by the haemoglobin. I'll see if I can clarify. Rockpocket 03:32, 17 December 2006 (UTC)
If you look at this albinotic cat, you see that the Iris looks pink and the pupil is a bit reddish too, because in the eye it is not as dark, as it should be. That is the reason why fully albinotic animals and people are half blind. Kersti Nebelsiek 16:14, 16 April 2007 (UTC)
The information presented by the snakevet guy is correct, and just for everyone's information, I believe that someone edited what he said with racial slurs. That happens a lot on this site, and that along with the large amount of disinformation in the articles is why I will not allow my students to use Wikipedia as a resource. Anyway, several experiments have been done on leucism, albinism and eye colour. I have read Reptile and Amphibian Variants by Bechtel and articles are out there on PubMed, or Scopus on the transplantation subject. Most of the published information indicates that the melanophore origin has no bearing, but it is a microenvironment issue. In fact, having done necropsies on many leucistic animals, I can tell you that they can have pigmented internal organs, while their skin is pigmentless. The melanomacrophages of the liver are also present in many leucistic animals. The origin of the melanophores in the internal organs is neural crest, yet they function. So at least in reptiles, the information stating that it is the origin of the cell that matters is absolutely WRONG. Transplanted melanophores or xanthophores from normal skin, do develop and function normally in albino skin, that is in the literature, look it up for yourself. If placed in leucistic skin, they perish. So in reptiles at least, it is a microenvironment issue, not origin of cells issue. There is also the annoying little fact, that it has not been established what the intraocular melanophores in reptiles arise from. It is an assumption that they do not arise from neural crest, but in truth, that is not established anywhere in the literature that I have been able to find.
As for the article itself, I would urge anyone to look up information on your own. I have generally noticed that this site has what one of my colleagues refers to as "territorial nerds" that will use the articles for their own opinion and support their arguments with a few citations and ignore other citations that do not agree. Once someone tries to change things and make the article more accurate, the territorial nerds come in and change everything back to the incorrect or incomplete information. I ran into this in another article with a person who eventually revealed he was a reptile hobbyist and would cite his article on Wikipedia when he gave talks to elementary schools, but the information was far from correct or up to date, and he would allow no one to change it. I get the feeling that may be the case here. --Vetpathol04 —Preceding unsigned comment added by 130.39.48.176 (talk) 16:10, 25 September 2007 (UTC)
