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What do T and T- mean in albinos? What other kinds of albinos are there and how do they determine the cause of the albinism?

Hi, Check out this web-site it has some info., on T-positive & T-negative (Tyrosinase)Albino Boa's, www.classreptilia.com look under "Boa Morphs" and read about the (Colombian Tyrosinase Positive (Carmel) Albino Boa).
Have A Good One ! !
Kenneth

The T stands for tyrosinase, which is an enzyme that catalyses the amino acid tyrosine to change into a chemical named L-dopamine. And other enzymes convert L-dopamine to something else. Ultimately, the final result of the chemical changes is melanin (black) pigment.

One cause of albinism is a malfunctioning tyrosinase enzyme.

A tyrosinase test takes a scrap of skin from an albino that totally lacks melanin pigment and incubates it in a solution of L-dopamine. This bypasses the possibly-malfunctioning tyrosinase enzyme. If the skin sample develops melanin, then the reasoning is that a malfunctioning tyrosinase enzyme is the cause of the albino condition. These are tyrosinase negative albinos. If the skin still does not form melanin, then the reasoning is that the tyrosinase enzyme is okay and that some other malfunction causes the albino condition. These are called tyrosinase positive albinos. This is okay up to this point.

A couple of years ago I asked Dave Barker whether anyone had done a tyrosinase test on any boas or pythons. He said no, and as far as I know, nobody has done a tyrosinase test on any boas or pythons yet. So nobody knows whether Kahl strain albino boa constrictors or Sharp strain albino boa constrictors are the tyrosinase negative albinos. For that matter, maybe neither one is tyrosinase negative.

Another problem is that many boa constrictors that have less black pigment than normal have been classed as tyrosinase positive albinos. The theory seems to be that any black pigment means a functional tyrosinase enzyme. Well, it's not that black and white.

The laboratory mouse has an albino mutant gene that produces a nonfunctional tyrosinase enzyme. It also has several other mutant genes that produce a partly functional tyrosinase enzyme producing a lighter than normal animal. And there are still other mutant genes that reduce or eliminate the black pigment. Different mutant genes explains why your T positive boa and my T positive boa may produce normal-looking babies.

So the "T positive" category is a mess. As far as I am concerned, "T positive" is code for "I don't have a clue as to what caused this lighter than normal condition."

Hope this helps.

Paul Hollander

np

A tyrosinase test takes a scrap of skin from an albino that totally lacks melanin pigment and incubates it in a solution of L-dopamine. This bypasses the possibly-malfunctioning tyrosinase enzyme. If the skin sample develops melanin, then the reasoning is that a malfunctioning tyrosinase enzyme is the cause of the albino condition. These are tyrosinase negative albinos.

Paul,
Actually a skin biopsy that produced melanin when incubated in L-dopa would be considered tyrosinase positive and not tyrosinase negative. The presence of tyrosinase is what allows the melanin to form in the biopsy, hence the designation T+.

If the skin still does not form melanin, then the reasoning is that the tyrosinase enzyme is okay and that some other malfunction causes the albino condition. These are called tyrosinase positive albinos.

Also incorrect. If the skin sample does not produce melanin when exposed to L-dopa then it would be considered tyrosinase negative since the presence of tyrosinase is required to make melanin. No tyrosinase = T-.

Hope this helps,
dg