ropotop Creative Commons License 2001.08.10 0 0 3394
Cloning: Facts and Fallacies
Tinkering with Mother Nature
Trepidation over humans creating duplicate people began in February 1997 when Dr. Ian Wilmut and his team of scientists in Scotland astonished the world by announcing that they had successfully cloned an adult sheep. Animals had been cloned before using the cells of developing embryos soon after they begin to form in the egg, but this was the first time ever that a mammal had been cloned from the cells of an adult animal. This major scientific breakthrough was accomplished by researchers in Edinburgh at the Roslin Institute, a center for genetic research of farm animals and PPL Therapeutics, a biotechnology company. The goal of their joint effort is to improve conventional animal breeding and create new health products for the biopharmaceutical industry.

In a process called “nuclear transplantation,” researchers took an udder cell of a six-year-old ewe and transplanted the nucleus (which contains the genetic material or DNA) into an unfertilized egg of a second sheep from which its nucleus had previously been removed. The cell and the egg were fused with electric pulses. The egg began to divide normally and developed into an embryo. It was then implanted into a third, surrogate sheep who gave birth to a lamb that is the genetically identical twin of the sheep from which the mammary cells were taken. The lamb named Dolly seems normal and healthy.

Clones Aren't Exact Copies
There is some misunderstanding about what constitutes a clone. A human clone would be the genetic identical twin, a generation or more younger, of the donor (not the surrogate mother) who provided the nucleus. But because people are more than a product of their genes, a clone would have its own personality, character, intelligence, and talents exactly as identical twins do (who are natural clones stemming from the same egg). You cannot clone a person's brain or mind, and chance factors, the environment, and a person's experiences contribute to individual traits.

This means that even if you wanted to, you cannot duplicate your identical self. Even if you were to clone yourself several times, you would not be able to create the same person each time because every human life, no matter how conceived, is unique. A cloned Hitler would not necessarily grow up to be a mass murderer nor would a twin of Mother Teresa become a humanitarian.

It is also impossible to copy a deceased family member or a past historical figure through cloning the cells from their corpses. The same applies to dead persons that have been frozen, because you need live DNA to make a clone.

Although some scientists believe that human cloning is only 10 or 20 years around the corner, the process would be far more difficult than cloning a sheep. Researchers began by attempting to fuse 277 adult sheep cells with an equal number of eggs. This yielded only 29 embryos, which in turn resulted in only 10 pregnant sheep, only one of which successfully made it to term and gave birth to Dolly. Given these odds, it would take dozens of surrogate mothers just to give birth to one human clone.

The biggest question over cloning animals is how the clone will age. Dolly was cloned from a six-year-old ewe and therefore the nucleus of all her cells were already six years old when she was born. No one knows how this will affect her longevity or other factors in her life.

Előzmény: Mumu (3392)