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and it's effects on animals that are heavily black (such as argentines etc). I saw one of John Mack's T Positive Argentines at the Chicago show and it was beautiful. However, I have also heard them described as albino Argentines. Is this a misnomer or are these 2 terms now used interchangeably?

Griz

Unless things have changed in the last couple of years, no boa constrictor has been tested for nonfunctional tyrosinase. In other words, there are no *proven* T negative albino boa constrictors.

I don't get out to the shows much so cannot comment on their word useage authoritatively. My personal opinion is that "albino" is used so loosely that any boa constrictor that is lighter than normal could get called an albino.

Alternatively, they might have been using "albino" for a specific line of T positive albinos. And they were relying on the context for identification of the line. After all, "albino" is a lot shorter than "John Doe's tyrosinase positive albinos".

What I would like would be a unique name for each mutant gene rather than lumping several together under "albino". But I'm not holding my breath.

Paul Hollander

I have seen first hand what 2 breeders called a T Positive Argentine. It was a very unusual looking animal. However, at the Chicago show, I see an identical looking animal that was referred to as an albino argentine. Hence my confusion. I actually purchased one of this animals offspring that is 66% het for T Positive from that very same show.

Griz

All normal boas are Tyrosinase Positive. Tyrosinase is an enzyme that produces melanin, and other darker pigments. In "T Albinos" the black areas are typical purplish/brownish, or lavender. I assume this is because the melanin(black) got knocked out, but other pigments produced by tyrosinase still remain. In the T- albinos the black areas are typically white. T albinos are sometimes referred to as lavender, or lavender albino, but this varies from species to species.

Tyrosinase does not produce melanin. Tyrosinase catalyses two steps in the biochemical assembly line that produces melanin. There are a variety of other enzymes that catalyse other steps in the melanin biochemical assembly line. A defect in any of these enzymes could produce a T-positive albino. A genetic defect that changes the shape, size, or distribution of the pigment cells or the pigment granules inside the pigment cell can also produce a T-positive albino.

In T-negative albinos, the black areas are typically white. In T-positive albinos, the black areas can be almost any shade that is lighter than black, including white.

Anything lighter than normal that isn't tyrosinase negative could be called a tyrosinase-positive albino. And there are dozens of ways to make an animal lighter than normal, including a partly functional (rather than nonfunctional or fully functional) tyrosinase enzyme. The coloration of a Siamese cat is caused by such a partly functional tyrosinase enzyme.

As there are no *proven* tyrosinase negative boa constrictors, all boa constrictors that are lighter than normal could be called tyrosinase positive albinos. There are dozens of different ways to make a "T-positive" albino. Which, in my opinion, makes the term useless as a category. It could still be used as the unique name of a single mutant gene, of course.

Paul Hollander

With the contention that "any light colored boa,(or any other species.)could be considered a T positive albino." while no clinical,or perhaps scientific tests have been conducted,that I'm aware of,to prove the identity of the anomoly to absolution,as being,in fact "tyrosinase positive albinism"...the condition,as it presents itself in boa constrictors,(there are currently three acknowledged strains.)has certain visually distinct characteristics that make it fairly difficult to ignore that they are,expressing some form of albinism,whether or not accepted by any scientific community,or faction thereof...because there may be slight differences in the causative biochemical anomoly at work in any one of these strains,they may look quite different from each other as adults,due in part to chemical changes brought on by aging,(hormonal,or ontogenetic biochemical changes.)...I feel that catagorizing these animals as T positive albinos is acceptably accurate based on the pupil pigment of juvinile examples,until some over-the-counter tyrosinase test kit is available at ones local drug store! (*lol*) the juvinile "eye test" will quickly weed out any wannabes,just my personal opinion...BTW the "extreme hypo Honduran milksnakes"(or whatever they're calling them these days.) are actually T pos. albinos,and NOT "hypos" at all! (IMHO,based on the pupil test.)
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Three acknowledged strains of "tyrosinase positive albino" is two too many. My point was that each mutant should have its own unique name to prevent confusion of identity.

As for hypo Honduran milks, they are both "T-positive albino" and "hypomelanistic". In my opinion, "hypomelanistic" is a more descriptive term. As it was applied first, there is no need to change.

Paul Hollander

There could theoreticlly be 100 strains of T pos. albino,(or one for each subspecies/race/locality specific island form,etc...)it doesn't mean they would all neccessarily be compatible,they don't need to be called anything different than what they appear & prove,(through breeding.)to be...example: we have two incompatible strains of T neg. amelanistic boas,both are obviously,(based on appearance)albinos,we don't need to come up with a different name for the second one,all we need is a name for the strain to distinguish between them....as for the Honduran thing...if there are both hypomelanistic & T pos. albinos,I can think of no particular reason to lump them together for the sake of "simplicity". two different anomolies-two different genetic terms,clinging to what they were originally thought to be would seem like a form of denial for the sake of convenience? as our perception changes so do the things we looked at yesterday. (or "should".)
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We agree on the first point, that there should be unique names.

As for the Honduran thing, I am definitely not trying to lump hypomelanistic and T-positive albino together. They are two different names.

To me, "hypomelanistic" means lighter than normal because of less melanin than normal. While "T-positive albino" means lighter than normal and with functional tyrosinase. Having any melanin means that hypomelanistic snakes have functional melanin. So as descriptions, the two mean the same thing.

When there are two or more names, and all mean the same thing, and as a description each name is acceptable, why not retain the one in common use?

If you think that hypomelanistic in boa constrictors does not look like hypomelanistic in Hondurans, then we agree. That is one of the reasons that I prefer the name "salmon" for the boa constrictor mutant. Hypomelanistic in Hondurans is more like hypomelanistic in corn snakes, which was discovered before hypomelanistic (salmon) in boa constrictors.

Paul Hollander

Perhaps I am not following this thread logically and am missing the point, but how would you propose diferentiating between two (or three or more) non allelically compatible strains? In Boas it has been shown that there are at least two strains, Leopard Geckos have three (and the potential for a fourth as yet unproven strain). While functionally they are all T animals, lumping them together seems to me to be saying that an egg is an egg regardless if it is a hummingbird egg or an ostrich egg. There is a fundamental truth there, but most would agree that the two are not the same thing.

There was an article written in either Vivarium, Captive Breeding, or Reptiles that theorized that hypomelanism as a variable state could eventually result in some form of amelanism. I will see if I can find that article and post a referance to it.

Just curious,

Ian

Sorry, my previous post should have read that the boas and leopard geckos were tyrosinase negative animal...

Ian

I don't object to lumping when lumping make sense. I object to lumping when splitting makes sense. At breakfast time, I want to eat a chicken egg, not just any egg. Or if I'm laying out high dollars to start breeding Sharp strain albino boa constrictors, I want to buy Sharp strain albinos and not just any albino.

Two or three years ago Dave Barker told me that no boa constrictor or ball python had been tested for tyrosinase activity. Unless that has changed, we simply do not know whether one, both, or neither strain of albino boa constrictor is tyrosinase negative.

I'm not up on the tyrosinase testing status on leopard gecko albinos. I'd be interested in any information about it.

Paul Hollander

In disputing whether,or not any of the boas which appear to be expressing tyrosinase positive albinism,have been clinicly,or chemicaly tested for tyrosinase activity...what I am saying is that visual criteria can be established to ascertain,or at the very least presume in the absence of microbiochemical testing,that an animal is expressing some sort of tyrosinase deficiency to the degree that constitutes a form of albinism. without test breeding them to each other,compatability,or synonymy cannot be proven."Why make up a bunch of fluff,brand names?" in the cases of locality,or distinct subspecific status preservation,many may opt not to test breed simply to be able to say the anomolies are the same...as for the comparison (from the other fellow.) about hypomelanism & albinism,that is true,(IMHO) T pos. amelanism is often mistaken for hypomelanism,as it was with the Argentine boas,and in my opinion,currently in the case of the "extreme hypo" Honduran milks....however,what we call "hypo",(salmon/orangetail) in boas is nothing like amelanism,and appears to be a distinct trait associated with Central American populations of boa constrictor ssp.(really very different from typical examples of true hypomelanism as seen in other species.also,IMHO)
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In re-reading the reply,the wording of the first part may be somewhat in error...I don't know that "tyrosinase deficiency" has anything to do with the actual occurance of amelanism,in,and of itself,(*lol*)...I should've perhaps said that a form of amelanism was being expressed & presumably some form of tyrosinase production seemed to be occuring in spite of that,based on appearence? ("hello,typing finger?...this is the brain,uhhh we're going to need you to go ahead & take a break there big fella." *LOL*)
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>In disputing whether,or not any of the boas which appear to be expressing tyrosinase positive albinism,have been clinicly,or chemicaly tested for tyrosinase activity...what I am saying is that visual criteria can be established to ascertain,or at the very least presume in the absence of microbiochemical testing,that an animal is expressing some sort of tyrosinase deficiency to the degree that constitutes a form of albinism.

I have no problem with stipulating that "tyrosinase positive" albinos have functional tyrosinase. I have no idea what the actual biochemical cause of their less than normal black pigment might be. But because of the presence of black pigment, though less than normal, I believe that they have functional tyrosinase.

I am not aware of any visual criteria on which to base more than the most tentative suggestion of tyrosinase impairment. On the other hand, lack of allelism with a tyrosinase negative albino mutant produces a high probability that the mutant does not impair the tyrosinase enzyme.

I did not make it properly clear that the boas that need testing are the Kahl and Sharp strains of albino. It is probable, in my opinion, that only one of them is tyrosinase negative albino. And the other has functional tyrosinase but is albino because some other enzyme is nonfunctional. That is the case in black rat snakes and gopher snakes. I just do not know whether to put my money on the Kahl or the Sharp strain. It is even possible that both have functional tyrosinase and that both are albinos for some other biochemical reason.

Paul Hollander