H.B. (Bern) Bechtel has done some tyrosinase testing on a few colubrid snakes. See his Amphibian and Reptile Variants book. My impression is that it isn't costly enough to break most of us. But it does take some equipment, lab skills, and access to bits of skin from various albinos.

A few years ago I asked Dave Barker if anyone had done tyrosinase tests on boas. He said that nobody had done such testing on any species of boa or python. That may have changed by now, but if so, I have not heard of it.

Back around 1985, Bechtel had a paper about black rat snakes in the Journal of Heredity. Using the tyrosinase test, he found one strain of albino black rat was tyrosinase negative, and the other was tyrosinase positive. Crossing the two strains produced a normal-looking, double heterozygous black rat snake. Aside from the tyrosinase test, the Kahl and Sharp strains of albino boas parallel the results from the rat snakes. In my opinion, one could be tyrosinase positive and the other tyrosinase negative, but I don't know which. Or both could be tyrosinase positive. I think it very unlikely that both are T-negatives. It doesn't work that way in mammals, at least.

I also think that hypo in boa constrictors is not the same as hypo in colubrids. That is one of the reasons I favor calling Rich Ihle's line "salmon boas" and not hypos.

There are lots of ways to make animals lighter colored than normal. Malfunctioning tyrosinase is only one. There are lots of things that break in a car and keep it from running. A dead battery is only one. If T-negative albino equals a dead battery, then T-positive is equivalent to making a grouping of cars with a good battery but something else wrong (broken ignition switch, plugged gas line, disconnected battery wire, burned out alternator, etc.). This sort of grouping is the result of ignorance masquerading as knowledge. Better would be an honest admission of ignorance.

The pro geneticists give a unique name to each mutant gene to minimize confusion among them. I think that boa fanciers are missing a bet by lumping at least three mutants together as T-positives. Unique names, especially sexy unique names, would minimize confusion and avoid giving the impression that anybody has a clue to the biochemistry involved. There are also sound marketing reasons for giving them sexy unique names.

By the way, melanin does not bind to the melanophore. Melanin is made inside the melanophore. Tyrosinase catalyses the first two chemical reactions in the series that changes tyrosine into melanin. Ultimately the melanin is deposited in a protein matrix and becomes a pigment granule. The process is complex and still not fully understood, as far as I know.

Paul Hollander

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