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fishkeeper
22nd November 2007, 04:04
quick definition for these terms here.

Albino is an individual lacking pigment?

Daniel
22nd November 2007, 13:04
If no one is especially interested in this topic I would like to write something on color genetics as soon as I find time (maybe in 10 hours...).
I can do it for axolotl coloration but do not know any special differences to other amphibia so if there are any, someone else will have to add it.

okay, here we go...a natural speaker should have a look at it when I'm finished

albino:color mutant where the dark pigments [melanin] and [eumelanin] are not developed in an animal.
[Pheotyp]ic expression: white or yellow with colorless / red eyes.
[Genotyp]ic expression: a/a - recessive and homocygotic for albinism.

leucistic: developmental mutation where pigment cells do not migrate from [neural crest].
[Phenotyp]ic expression: white with more or less dark spots / patches on head and backside with black eyes.
[Genotyp]ic expression: d/d - recessive and homocygotic for leucistic.

melanistic (melanoid?): color mutant where the shiny pigment cells ([iridophores]) are not developed.
[Phenotyp]ic expression: mostly dark animal without shiny spots / patches on the body. Eyes black without shiny ring.
[Genotyp]ic expression: m/m - recessive and homocygotic for melanism.

xanthic: not sure, only know "axanthic". xanthic should be with yellow xanthophores.

Kaysie
22nd November 2007, 21:55
Axanthic: lacking [xanthophores] (which produce yellow pigment), usually leading to a dark individual

Amelanistic: lacking [melanophores] (which produce dark brown/black pigment), often leading to very pale individuals (which may still have other colors present)

Jennewt
23rd November 2007, 19:38
I think these words can all be defined in the same thread. Some of my color pigment info is plagiarized from axolotl.org.

Leucistic: Having a reduced amount of melanin or lacking [melanin] in particular body parts. (?) Leucistic animals are often white with black eyes.

Melanoid: An animal that lacks [iridophores].

Flavistic: Is this even an English word? I cannot find it in dictionaries. Is it a foreign term for leucistic?

Chromatophore: Pigment-containing cell of the skin. There are several different kinds of chromophores, each containing different types of pigment(s). These include melanophores (containing melanin, a brown-black pigment), iridophores (containing crystals that impart a shiny iridescence), and xanthophores (containing carotenoids and pteridines, yellow and reddish pigments). For more information see [axolotl.org color genetics page].

Iridophore: A pigment-containing cell that contains crystals that impart a shiny iridescence. See [chromophore].

Xanthophore: A pigment-containing cell that contains carotenoids and pteridines, which impart yellow and reddish pigments. See [chromophore].

Melanophore: A pigment-containing cell that contains melanin, a brown-black pigment. See [chromophore].

Melanin (or eumelanin): a brown-black pigment that gives color to the skin of many amphibians.



I have no idea what the difference is between leucistic and flavistic. Anyone know?

Kaysie
24th November 2007, 01:39
Flavistic I think means having increased yellow pigment.

Jennewt
25th November 2007, 23:54
Here I will attempt to assemble what we have so far:

Albino (albinism): Color mutant in which the dark pigments ([melanin] and [eumelanin]) are not developed. Animals are usually white with pink eyes.

Leucistic: A developmental mutation where pigment cells do not migrate from the [neural crest]. The resulting animals are usually white with black eyes.

Melanistic (or melanoid): color mutant where the shiny pigment cells ([iridophores]) are not developed. Melanoid animals are usually much darker in color than normal.

Xanthic: Having more yellow pigment ([xanthophores]) than normal.

Axanthic: Lacking [xanthophores], which produce yellow pigment, usually leading to a dark individual.

Amelanistic: Lacking [melanophores], which produce dark brown/black pigment, often leading to very pale individuals (which may still have other colors present).

Chromatophore: Pigment-containing cell of the skin. There are several different kinds of chromophores, each containing different types of pigment(s). These include melanophores (containing melanin, a brown-black pigment), iridophores (containing crystals that impart a shiny iridescence), and xanthophores (containing carotenoids and pteridines, yellow and reddish pigments). For more information see [axolotl.org color genetics page].

Iridophore: A pigment-containing cell that contains crystals that impart a shiny iridescence. See [chromophore].

Xanthophore: A pigment-containing cell that contains carotenoids and pteridines, which impart yellow and red pigments. See [chromophore].

Melanophore: A pigment-containing cell that contains melanin, a brown-black pigment. See [chromophore].

Melanin (or eumelanin): a brown-black pigment that gives color to the skin of many amphibians.

Flavistic: a color mutant that has a yellow or golden color.


Unresolved:
Daniel, I'm not sure I understand your notes about phenotypic and genotypic expression. It may be too detailed for our audience.

Harlequin and piebald. Are these the same?

What is the difference between melanin and eumelanin?

Golden albino?

Daniel
26th November 2007, 14:17
I had a look into this melanin-thing again: eumelanin is a special kind of melanin, it's even described in wiki: http://en.wikipedia.org/wiki/Melanin
So it would be easier to understand if we only use "melanin" as this is some kind of collective noun.

We can leave the phenotypic/genotypic part aside if that is too detailed (in the descriptions so far we only have phenotypic - so to say "visible" definitions); I wanted to explain that color mutants (albinoid, leucistic, melanistic, axanthic) are always (at least in axolotls) recessive and genetically the animal has to be homocygote for this mutant. At least I would like some short definitions for the basic biological words in the glossary: homocygote - heterocygote, recessive - dominant, gene, allel

Every now and then there are questions in the axolotl section of the forum like "I have white and an albino axolotl but some of the offspring seems to be wild type, is this possible?"
But this information is also explained at the color genetics section of axolotl.org

Harlequin and Piebald: I have to admit that I am not so happy with these artificial typing. In my opinion harlequins and piebalds are almost always leucistic axolotls with a higher amount of dark pigments - genetically they obviously are the same as "normal" leucists with a different phenotype.

Golden albino: that's a "normal" albino, too.

"White albinos" lack melanin (the pigment itself) and xanthophores (the pigment cells) or they are combined with leucism (xanthophores are developed, but do not migrate from the neural crest, therefore the animal has only a hint of yellow on head and back).

Whereas golden albinos only lack melanin, xanthophores are expressed so the whole body has a yellow / shiny coloration.

I think we do not need special pictures on that for it's on axolotl.org?

Question on melanoids: In my experience melanoids are not necessarily much darker than normal wildtypes. The only definite characteristic is the missing shiny ring in the eyes.

I added some typos to your text - "chromophore" should be "chromatophore" or are both possible?



Albino (albinism): Color mutant in which the dark pigments ([melanin] and [eumelanin]) are not developed. Animals are usually white or yellow with pink eyes.

Leucistic: A developmental mutation where pigment cells do not migrate from the [neural crest]. The resulting animals are usually white with black eyes.

Melanistic (or melanoid): color mutant where the shiny pigment cells ([iridophores]) are not developed. Melanoid animals are usually much darker in color than normal.

Xanthic: Having more yellow pigment ([xanthophores]) than normal.

Axanthic: Lacking [xanthophores], which produce yellow pigment, usually leading to a dark individual.

Amelanistic: Lacking [melanophores], which produce dark brown/black pigment, often leading to very pale individuals (which may still have other colors present).

Chromatophore: Pigment-containing cell of the skin. There are several different kinds of chromatophores, each containing different types of pigment(s). These include melanophores (containing melanin, a brown-black pigment), iridophores (containing crystals that impart a shiny iridescence), and xanthophores (containing carotenoids and pteridines, yellow and reddish pigments). For more information see [axolotl.org color genetics page].

Iridophore: A pigment-containing cell that contains crystals that impart a shiny iridescence. See [chromatophore].

Xanthophore: A pigment-containing cell that contains carotenoids and pteridines, which impart yellow and red pigments. See [chromatophore].

Melanophore: A pigment-containing cell that contains melanin, a brown-black pigment. See [chromatophore].

Melanin: a group of brown-black pigments that give color to the skin of many amphibians.

Flavistic: a color mutant that has a yellow or golden color.

Jennewt
28th November 2007, 03:33
OK, here's everything we have so far. (Thank you for the details and edits, Daniel!) I'll declare this finished, though if anyone has anything to add, go for it.

Albino (albinism): Color mutant in which the dark pigments ([melanin]) are not developed. Animals are usually white or yellow with pink eyes.

Leucistic: A developmental mutation where pigment cells do not migrate properly. The resulting animals are usually white with black eyes.

Melanistic (or melanoid): color mutant where the shiny pigment cells ([iridophores]) are not developed. Melanoid axolotls are sometimes darker in color than normal and lack the shiny ring around the eyes.

Xanthic: Having more yellow pigment ([xanthophores]) than normal.

Axanthic: Lacking [xanthophores], which produce yellow pigment, usually leading to a dark individual.

Amelanistic: Lacking [melanophores], which produce dark brown/black pigment, often leading to very pale individuals (which may still have other colors present).

Chromatophore: Pigment-containing cell of the skin. There are several different kinds of chromatophores, each containing different types of pigment(s). These include melanophores (containing melanin, a brown-black pigment), iridophores (containing crystals that impart a shiny iridescence), and xanthophores (containing carotenoids and pteridines, yellow and reddish pigments). For more information see [axolotl.org color genetics page].

Iridophore: A pigment-containing cell that contains crystals that impart a shiny iridescence. See [chromophore].

Xanthophore: A pigment-containing cell that contains carotenoids and pteridines, which impart yellow and red pigments. See [chromatophore].

Melanophore: A pigment-containing cell that contains melanin, a brown-black pigment. See [chromatophore].

Melanin: brown-black pigments that give color to the skin of many amphibians.

Flavistic: a color mutant that has a yellow or golden color.

Harlequin: a [leucistic] axolotl in which some pigment occurs on the body, often in specks or blotches. Synonym: piebald.

Piebald: a [leucistic] axolotl in which some pigment occurs on the body, often in specks or blotches. Synonym: harlequin.

Hypomelanistic: an animal with a reduced amount of [melanin] in the skin, giving it a color that is significantly lighter than normal.

Hypermelanistic: an animal with an increased amount (or distribution) of [melanin] in the skin, giving it a color that is significantly darker than normal.

Erythristic: having a greater amount of red coloration than usual.