ASK A SCIENTIST
Question: Can you really clone a person and an animal?
Wow, that's quite a question for this amount of space. The ethical considerations alone could fill up volumes of books. I will focus on the process of animal cloning and the resulting organism. Not only is animal cloning possible, but several species have already been cloned including mice, pigs, sheep, cattle, cats, and there are even claims that humans have been cloned, though these reports are completely unsubstantiated. Surprisingly, and for unknown reasons, cloning dogs has not been successful.
The majority of animal cloning is accomplished through a process called nuclear transfer where the nucleus of an egg is removed and replaced with the nucleus from an adult somatic cell. The egg is then stimulated chemically to begin embryonic development. Soon after, the dividing cell mass is transplanted into the uterus of a surrogate mother, and if things go perfectly it is possible that a genetic clone of the donor will be born.
While the cloning of the first mammal in 1997, a sheep named Dolly, was a remarkable scientific breakthrough, many problems still exist with the cloning process and with the offspring that are created from this procedure. First, only 1% of all cloning attempts result in viable offspring. It took 277 tries to produce Dolly, who was the result of extracting the DNA from a mammary cell of a six year-old sheep and inserting it into the enucleated egg from a different type of sheep.
Second, a high percentage of the viable offspring have serious medical conditions that occur during adolescence. Dolly had a progressive lung disorder and severe arthritis requiring that she be put to sleep when she was only six-and-a-half years old, about half the lifespan of a typical sheep. However, while chronologically she was only six-and-a-half years old, her genetic age was twelve-and-a-half, since the donor DNA was extracted from a six year-old sheep. For this reason, scientists are now debating the possibility that cloned animals may be starting life at an advanced age. Adverse medical conditions have also been well documented in other livestock, prompting the Food and Drug Administration to request that food manufacturers cease the introduction of cloned animals or their products into the food supply until the safety of animal cloning has been established. A full-report is due to be released by fall 2004.
Finally, and perhaps most importantly, while identical to its donor at the gene level, a cloned animal will not be an exact replica of its donor. Let me repeat- cloning does not result in duplication. Memories, life experiences and environmental exposure cannot be cloned. This was strikingly apparent in the first cloned cat, named CC (Carbon Copy). Rainbow, the donor cat and CC's "mom", is a calico with regions of brown, tan and gold on white, while CC has a striped gray coat over white. Further, the two cats have completely different activity levels and behavior. In reality, they are two distinct cats. So the next time you get the great idea to clone your cat (only $50,000 at your friendly neighborhood cloning center), just remember that you'll likely end up with an animal that looks and acts completely different from your cuddly critter.
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