Animals come in all shapes, sizes, colors and forms, but some stand out more that others, and chimeras arguably stand out most of all. These amazing creatures are the result of a genetic anomaly that leaves them with startling fur patterns and other features. Read on to learn more about these rare creatures, and how to identify one for yourself.
What is a chimera?
A chimera is an organism (animal, human, etc.) that is made up of two or more genetically different cell lines. This means the organism can produce different DNA genotypes depending on what area of the animal a DNA sample is drawn from. Because of these merged genetic codes, the organism is essentially a mixture of two organisms fused together. Each population of genetically different cells keep their traits, causing unusual internal and external changes on and in the animal.
How are chimeras formed?
Chimeras are formed by the fusion of four parent cells. Usually this occurs when two fertilized zygotes fuse together. The fertilized egg then progresses like a normal pregnancy and the animal is born. Often it is hard to tell if an animal is a chimera unless the outward appearance of the animal is affected.
How does chimerism affect an animal's health?
Most chimeras go through life with their genetic differences undiscovered. Research has shown that animals and humans live safely with organs that do not share the same genetic code, so many chimera organisms lead normal lives, ignorant to their internal differences. Chimerism is not usually noticed unless there is abnormal skin or eye pigmentation, or if a merger between XY/XX zygotes creates ambiguous genitalia or hermaphroditism. In a case where sex organs are affected, chimerism can effect the individual's fertility.
Do people breed chimera animals?
No, chimera animals are not bred to create more of the same. Since chimerism is the result of a genetic anomaly, it is not something that is hereditary. The chances of chimera offspring does increase with in-vitro fertilization. Once again, the majority of chimera animals can successfully reproduce, unless the chimerism affects the sexual organs, but these offspring will most likely not be chimeras as well.
Are there different forms of chimerism?
The general form of chimerism is the fusion of two zygotes forming either a XX/XX, XY/XY or XY/XX animal, resulting in a relatively even distribution of the two different genetic codes. There is also microchimerism, where only a small portion of cells are genetically different from the rest of the organism. These cases almost always go undetected. Finally, there is parasitic chimerism, which is seen in anglerfish. The small male will attach himself to a female and fuse with her. As the male sexually matures, the rest of his organs atrophy, resulting in hermaphroditic anglerfish that can reproduce with itself.
What is the history of chimerism?
The chimera in Greek mythology is a fire-breathing creature that is both male and female. It usually is represented by an animal that has a lion head and a goat head attached to a body with a snake tail. "Chimera" was a term used to described a fictional creature made out of numerous animal parts, or anything that was wildly imaginative.
Does chimerism occur In humans?
There have been several reports of human chimeras, who usually are discovered by a DNA test for something else, or due to to ambiguous genitalia. There are probably many more human chimeras than the few on record, because chimerism is easy to overlook unless there are external signs, or a DNA test shows something unusual. Doctors are also discovering microchimerism is fairly common in humans, and usually not a threat to an individual's health.
What's the difference between a calico and a chimera?
Calicos get their signature coat due to an effect on the X chromosome. In all but a few rare cases, the animal is female, because it takes two X chromosomes for the effect to appear visually. While the calico's coat is similar to a chimera animal's, they are not the same thing. Calicos are the result of normal zygote development, meaning an egg was inseminated by a single sperm and developed into an organism with one genetic code. Some chimeras look like calicos because the expression of both their genetic codes cause them to have two coat colors that merge together.
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What are some known examples of chimera animals?
Viral star Venus the cat is a chimera. Her different colored eyes and the spilt coat color on her face are expressions of her different genetic codes. Tiger the Labrador Retriever also is a chimera. Her owners discovered this after their two purebred Labs produced a puppy that was spotted. In purebred Labs, the entire coat is usually one solid color, usually black, brown or yellow.