Albinosim in Boa Constrictors
Oculocutaneous albinism is an autosomal recessive mutation which results in the absence or decrease of melanin, producing a yellowish snake sometimes with red eyes. There are two mutations which result in the albino phenotype due to a mutated tyrosinase enzyme.
Tyrosinase is an enzyme produced by melanophores (a type of chromatophore aka a pigmentation cell) which converts the amino acid tyrosine into dopa and then into dopaquinone. Dopaquinone is modified into melanin and deposited into dermal and epidermal melanophores. These melanophores produce brown and black pigmentation giving the snake its base coloration. Other types of chromatophores found in snakes include xanthophores (yellow pigments), erythrophores (red pigments), leucophores (white pigments), these cell pigmentation cells are not affected by any tyrosinase mutations.
The first type of albino mutation is the tyrosinase negative mutation, this is the more severe form. The melanophores in these albinos do not synthesize the tyrosinase enzyme and thus do not produce melanin. With only the xanthophores, erythrophores, and leucophores producing pigmentation these animals are often yellow in appearance with red eyes.
The second type of albino mutation is the tyrosinase positive mutations. These animals have melanophores which synthesize a functional tyrosinase enzyme and produce melanin, however, the deposit of this melanin into melanophores is highly impaired. This allows for the production of red, yellow, gray, brown, and white pigmentation. The reduction in melanin allows produces an exaggerated red appearance.
All albino mutations are recessively inherited. In order to express this mutation, a boa must have two homologous alleles of the albino mutation gene. If a boa only has one mutated allele and one normal allele then the animal is heterozygous and the phenotype will be that of a wild boa. However, the allele for the albino mutated can still be inherited by offspring. Because these mutations occurred on different chromosomal locations, separate lines of albinism are generally incompatible. Crossing two separate lines would result in offspring displaying a wild phenotype, for example crossing a Kahl and sharp.
The Kahl line of tyrosinase negative albinos originates from South American boas. Two variations within this strain exist; the coral and lipstick lines. The coral line has been selectively bred for pinkish hues while the lipstick line has been bred for increased reds.
The Sharp line is another example of tyrosinase negative albinos originating from South American boas.
The Blonde line is an example of a tyrosinase positive albino which originates from South American boas.
The VPI albino boa is one of the most common tyrosinase positive albino boas, also originating from South American boas. They are often caramel in color. Specific breeding has resulted in the creation of “Pink Panthers”.
The Boa-Woman Caramel is another line of South American tyrosinase positive albino boas. This line is unique due to the reduction or absence of black pigmentation, which is replaced with shades of brown.
The Central American lines of tyrosinase positive albino boas are easily distinguished from the South American boids due to their intense orange and reds.
