Reptile & Amphibian Forums

Ok. I searched the forums and since noboday else is going to say it I will.
What's the deal here? I mean I totaly understand that Axanthic is the lack of yellow color produced by xanthophores. Anerythristic is the lack of red color produced by xanthophores.
Both are the total lack of xanthophores. These two names are the same genetic anomoly. I have researched and searched for a difference and I can't find nothing anywhere. Since when do you find an anerythristic animal producing yellow or an axanthic producing red? You don't because to produce both colors it needs the same Cromatophore the xanthophores. Someone tell me if this is just some crazy joke or what?

You might want to check anerythristic, charcoal, and caramel in corn snakes. These are three independent mutants. The first two block formation of red pigment, but they seem to do it in different ways. Caramel seems to dilute the red color to yellow color.

The biochemists tell us that the formation of a given pigment is the result of a long biosynthetic pathway, with considerably more than one step. A block or diversion at any of the steps could change what we see. In other words, there is more than one way to skin a cat or prevent yellow/red pigment from forming.

As for anerythristic vs. axanthic, it boils down to which color appears in a normal specimen of the species and is lacking in the mutant specimen. And if you are naming such a mutant but dislike both terms, choose a different name.

Paul Hollander

Thank you for your reply Paul. I have researched this for quite a while now and what you said is what I pretty much come up with as well. The color the animal is primarily lacking would indicate what it would be refered to as. I also have come to the belief that an anerythristic pretty much has to lack red. While an axanthic could lack either red or yellow. My reason for saying so is that (anerythristic) broke down would be (An=lacking, erythristic=erythrism a name for a redish pigment condition). And then (A=lacking, xanthic=xanthophores an actual name for a chromataphore that produces red and yellow pigments). Meaning that Axanthic would be the "politicaly correct term" that would cover anything that lacks the xanthophores, while the term anerythristic would only cover the lack of red. So an animal that normaly has red and yellow colors would by true definition be axanthic for example a brooks kingsnake.
cheers, Celt

Animals that lack xanthophores would be axanthic. Animals that have xanthophores which are unable to make yellow/red pigment are also axanthic.

I believe H.B. Bechtel has a discussion of xanthophores in his amphibian and reptile variants book.

Otherwise, we are basically in agreement.

Paul Hollander

I believe we are probably in agreement. I do however believe that the animals that don't lack xanthophores that can not produce the red or yellow pigment may be called axanthic, however that would by technical definition be wrong. The prefix A in a-xanthic means lacking the xanthophore chromatophore. Just like hypo-xanthic would mean reduced xanthophores, and hyper-xanthic would mean more then normal xanthophores. I do not disagree that people would still consider an animal that has the xanthophore chromatophores that can not produce red or yellows still axanthic though just not by proper definition.

cheers, celt

Check the definition of xanthic at http://dictionary.reference.com.

Paul Hollander

Touche'
You ever watch that new game show "Are You Smarter Than a 5th Grader"? Everywhere I read about Axanthic it was stated that it is the condition caused by the lack of xanthophores. (Axantic - xanthophores) I never even thought to do a search for xanthic. I did not know it was a word it'self. Well just when you think you have it all figured out. Here you come and now it's just as big a mess as when I first started trying to figure it out. So now I figure that Axanthic and Anerythristic are basicly lack of yellow pigment, and lack of red pigment. Both may or may not be caused by lacking xanthophores but most likely would be.

Thanks very much for all your help Paul

Cheers, Celt

The ambiguity with xanthophore is that they represent not only yellow colored pigment holding cells but also red colored pigment. It has been common practice to name a xanthophore that hold mainly yellow pigments "xanthophore" and a xanthophore that holds mainly red pigments "erythrophore". This can be quite confusing at times, and I personnally chose to use xanthophores (in a herpers language) regardless of the color of the pigments, since it's biologically the same cells. Axanthic, erythristic, anerythristic , in the herpers world commonly reffers to the visible colors. Biologically, xanthophores could actually be termed Pterinophore for they synthesize and hold pterine pigments which can be different reds, orange or yellow. Each of these pigment has a different chemical pathway, but all of them start with GTP-CH1 catalysing GTP into the further steps leading to one or more different pterins (such as sepiapterin or xanthopterin). The chemical pathway of these pterin pigments implicate different enzymes. A mutation inhibiting GTP-CH1 should normally inhibit the production of ALL pterin pigments. Inhibiting another enzyme may only inhibit the production of selected pigments. It may be worth mentioning that xanthopterin has a chemical pathway much different than that of many red pterins.

JF Dery

I am a Biochemist and a snake breeder and I understand your confusion Celt, because in the snake world the rules of scientific nomenclature are often thrown out the window, usually naming it is a visual phenotype judgement call, because nothing is known at the time as to what is going on at a molecular genetics level. So sometimes what is called one is maybe really the other ect, ect. Also as you know many many morphs now have zero scientific nomenclature basis to charaterize the genetics, they are simply "catchy" and "cool" marketing "buzz words"
The ball python morph naming is way ahead of science, but the corn snake world is in much better shape and more in line, as I believe Paul eluded to, look to corn snakes as better examples.
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Jeff Benfer
You'll get your regius's to the wall, man!
1.0 pastel Python regius
1.1 mojave Python regius
0.1 normal Python regius
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2.3 Terrapene carolina carolina
4.1 Kinosternon baurii
1.1 Malaclemys terrapin terrapin
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1.0 anerythristic Thamnophis sirtalis parietalis
2.2 Iowa snow Thamnophis radix
0.1 het Christmas albino Thamnophis radix
1.1 double het cherry erythristic, albino Thamnophis sirtalis sirtalis
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