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The basic formula of life, DNA, can now be copied like a file from Napster.com, and there is no copyright. Cloning, once a denizen of sci-fi films and books is now being attempted in various parts of the world for various purposes.
Researchers provide three reasons for human cloning: to provide organs to be transplanted, to allow parents to clone a dead or dying child, or adults who want to clone themselves.
“It’s unethical because then you lose the concept of identity between the original person and the clone,” junior biology major Dana Cavalcanto said.
As with identical twins, clones would be very different individuals. While the appearance of the clone and the original would be indistinguishable, on the molecular level, differentiation is possible. As with identical twins the fingerprints of a clone and an original will be different. For one, the clone’s mitochondria (the energy-producing cell parts) would come from the egg donor, while the original’s would be consistent with their DNA. Clones are essentially younger identical twins.
You may remember “Dolly,” the sheep cloned in Scotland in 1997. Scientists are unsure of whether all clones will be fertile, yet Dolly has successfully given birth to four lambs.
Dr. Louis Nudy, professor of chemistry, supports research into the benefits of human cloning. “It is something that needs to be studied considering the risks and benefits to the new offspring and society as well,” Nudy said.
Human cloning is much more complicated than the cloning of animals because of the size of the human genome. Dolly required more than 276 attempts before success. Some scientists fear that before a human clone is successful, there will be many cases of malformations or diseased human clones.
There also is the question of whether the age of the DNA used for the clone will affect its life span.
An international team of scientists at the University of Hawaii, led by Ryuzo Yanagimachi and Teruhiko Wakayama, has cloned adult mice more than 50 times, including some sixth generation animals – clones of clones of clones, etc. Yanagimachi’s group has also produced the first male clones. While the production of Dolly resulted in 276 failures, the male mice resulted in 274 failures. Of the three live male mice produced, two died almost immediately after birth.
However, unlike previous attempts, the mice’s telomeres are longer than expected. Telomeres are caps that protect the DNA of a chromosome and sustain cellular life (see below).
“Our results verify that telomere shortening is not a necessary outcome of the cloning process,” Wakayama said.
Researchers at Advanced Cell Technology, based in Worchester, Mass., have cloned six heifers (female cows) from a 45-day-old fetus. The cows appear to be younger than their chronological age.
“We have shown that the clock gets reset,” Dr. Michael West said, president and CEO of Advanced Cell. “It remains to be determined whether this would extend the life of the animal.”
Dolly’s chromosomes are showing signs of premature aging. Dolly’s cells are the same age as those of the 6-year-old ewe from whom she was cloned. This is determined by looking at the telomeres, which wear with each cell division. Researchers from the Roslin Institute and PPL Therapeutics in Edinburgh, Scotland report Dolly’s telomeres are 20 percent shorter than those of sheep the same age.
Some scientists believe telomeres may hold the secret to aging.
The cells used by the Advanced Cell group were reaching senescence before the transplant because the process was slightly different from that used for Dolly. The original donor cells may make the difference – mammary cells for Dolly and connective fetal cells for the six heifers.
“The egg cell acts like a little time machine and can take [the DNA] back to the beginning of life,” West said.
In an article written for “Scientific American,” Ian Wilmut, the man who cloned a sheep at Roslin Institute, claimed that “once techniques for the retrieval of egg cells in different species have been perfected, cloning will make it possible to introduce precise genetic changes into any mammal and to create multiple individuals bearing the alteration.”
This raises troubling questions. If we are able to alter the genes of an individual to create specified attributes where do we draw the line in designing humans.
Fuller-Espie feels it is unethical to use cloning to improve human stock. “It is one thing for gene therapy of somatic cells – not germ cells – to correct a deficiency and another thing to use the whole genome for another purpose,” Fuller-Espie said. “I think it is not for humans to interfere in God’s work.” Fuller-Espie further explained that gene therapy on somatic cells is not inherited by the next generation.
According to Donum Vitae, a 1987 Vatican document, cloning violates “the dignity both of human procreation and of the conjugal union.” Protestant theology often supports scientific ventures. This derives from the common Protestant belief that nature is “fallen.” However, cloning of humans goes too far, according to many Protestant theologians. Rabbi Richard Address, member of the Union of American Hebrew Congregations, said human cloning “violates the mystery of what it means to be human.”
Cloning can benefit the research into animal transplant organs. There is a similarity between the organs of pigs and humans; however, the human immune system attacks the tissue of other species, particularly certain pig enzymes. Alexion Pharmaceuticals, a biotech company based in Connecticut, is attempting to alter the pig genetic code to prevent transplant rejection. Wilmut also points out that animals who have had their genome altered to resemble humans with diseases like cystic fibrosis and Parkinson’s disease may permit more intensive studies of gene-based therapies.
Yet, Wilmut admits to a limited success rate. According to Wilmut, laboratories report that 1 to 2 percent of embryos survive to become live offspring, and some of those clones die shortly after birth. The Scottish team produced one live lamb from 29 clones placed into 13 ewes.
While the benefits of cloning are many, the road to producing viable human clones, or even satisfactory healthy animal clones, stretches farther in front of us than behind; and many questions remain unanswered.
“We should be asking ourselves, `why do we need to clone, who is it going to benefit?'” Fuller-Espie said. Fuller-Espie believes that global guidelines and boundaries need to be placed on cloning, esp
