The science behind color patterns of calicoes, torties
When I was last at the shelter, I noticed the beautiful array of coat colors and patterns on our felines.
I wondered, what change in genetic makeup determines a predisposition for tortoiseshell or a tortoiseshell with white (a tri-colored coat), otherwise termed calico? I am referring to coat marking, not a specific breed of cat. Tortoiseshell markings (tortie) can be found in specific breeds of cats, as can tortie with white.
Torties are usually felines that have brindled, bicolored coats, where the colors are intricately intermingled. Typically, they will not have any white and will be less patchy than a tortile with white, also known as calico.
Tortie and calico coats result from a combination of genetic and developmental factors in the embryo. The formation of red and black coloration in a female is called X chromosome inactivation.
The O gene represents red pigmentation. It is carried by the X chromosome. If a female has two O genes, she will be red; on the other hand, if she only inherits one O, she will be tortoise. When the second X is inactivated, the black color appears.
What next determines the pattern of the coat for brindled or patchy? Pigment colored genes that arrive early usually produce brindle because they have more time to interact with each other.
If the X inactivation occurs later, the brindle will be more intricate because the cells have less time to interact and less room to multiply. The cells have less time to compete against each other, if you will, which can cause a ticking pattern to the fur.
Ticking occurs when each hair can have both colors. A good example of a breed of ticked feline is the Abyssinian. They are tri-ticked.
In tortie with white felines, another genetic factor comes into play. A spotting gene produces white, unpigmented patches by delaying pigment color to the skin's surface. The later the pigment migration, the more likely our feline will be patched with significant amounts of white fur. In an extreme case, a feline may not have any pigment to its skin. In that instance, we have a totally white animal, but not albino.
Torties and calicoes also come in an array of color combinations such as cream, blue, lilac and fawn, These are all lighter shades. The dilution genes are responsible for these lighter colorations.
Torties and calicoes, in general, earn their spots from a series of gene mutations. That is just why they are so special.
If I had to offer some generalizations on torties and calicoes based on my own household, I would say the darker the more vocal, closer to an oriental or Siamese meow, and perhaps more temperamental.
The blues and creams, if not oriental looking, seem to be very affectionate. For sure, the safest generalization about blues and creams, they are very showy and much more rare than the darker varieties.
Black Cat Adoption Event:
Sept. 1-30 at the shelter, 65 W. Seegers Road, Arlington Heights. During the Black Cat Adoption event, the adoption fee will be lowered to $75 for black cats. For information, visit www.thebuddyfoundation.org or call (847) 290-5806.
Sixth annual Mutt Strutt:
9 a.m. Sunday, Sept. 10, Melas Park, 1500 W. Central Road, Mount Prospect. Walk with (or without) your dog and help raise money and awareness for The Buddy Foundation. Walk with your friends, family, and co-workers. $35 per person; $10 for ages 12 and younger.
• The Buddy Foundation, 65 W. Seegers Road, Arlington Heights, is a nonprofit 501(c) 3 shelter. Call (847) 290-5806 or visit www.thebuddyfoundation.org.