Why not cloned animals always look the same

Clones : Not quite the mom

Life still writes the best stories. Like Booger 2.0. It was years ago when the now 58-year-old Hollywood screenwriter Bernann McKinney was brutally attacked by a dog. Her own pit bull terrier, Booger, jumped in and saved the woman's life. That was the first act.

Then came the catastrophe: Booger died of cancer in 2006. But McKinney did not want to be satisfied with this end and knitted himself a new one. Using tissue from the ear of her heroic dog, kept in the refrigerator, she had Booger cloned in a genetic laboratory in the South Korean capital, Seoul. Finally, on Tuesday, the time had come and McKinney was able to hug five cloned pit bull babies: "It's a miracle," said the overjoyed woman. "You look just like your papa and are completely identical."

Happy end? Not quite. Several findings now point to something that amazes even genetic researchers themselves: clones are neither identical in terms of behavior nor appearance. Rather, each clone develops its own, individual identity.

This became clear at the latest when the first pet, a cat named "Cc", was cloned in 2001. Cc stands for "Carbon Copy", ie carbon paper. But Cc is anything but a “carbon copy” of its biological mother Rainbow. Rainbow is white with brown and gold spots. Cc is also white, but has a different pattern and a touch of gray. They also differ in their behavior: Rainbow is cautious and reserved, Cc is curious and playful.

This is not an exotic exception. US researchers cloned pigs in an experiment and found that one animal surprisingly had a curly coat while the others were straight. One pig had an extra teat, some preferred different feed than their clone siblings, and the clones were not all the same when it came to temperament. "Cloning technology has been sold to the public as a way to make identical animals, and companies are offering pet cloning," said Jorge Piedrahita, one of the participating researchers from Texas A&M University. "The tacit assumption is that the cloned animal will behave and look like the animal you already have - and that is not the case."

There are several reasons for this. First, the clones are not completely genetically identical. The main inheritance of the clones comes from the original animal, such as Booger. But this genetic material has been transplanted into an egg cell that comes from another animal and which still has its own genetic material in the cell sap. This extra genetic material can contribute to the dog's growth and size. In addition, the genetic material is biologically reprogrammed in the course of embryonic development. Depending on the animal, different genes are switched on and off, determined by random processes and individual environmental influences.

Education comes later. The unique experiences that every animal has, change its brain structure and thus the character of the animal. Different creatures emerge from five puppies with the same genes. “Booger was an angel God lent me for a short time,” says McKinney. “And God knew I would be lost without him, so he sent me a few more. He sent me five more mini-boogers. “Really? It looks like the script around Booger 2.0 could come to a more surprising ending than the author McKinney imagines.

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