Главная > Реферат >Остальные работы
On February 23rd of 1997, an announcement was made that would shake the world and, inevitably, change it forever. Ian Wilmut, an embryologist with a genetic research facility named the Roslin Institute in Scotland, claimed that he and a group of scientists had successfully cloned a sheep. The sheep, named Dolly, was revolutionary in the Bioengineering world because it was the first mammal to be cloned directly from the genetic material of another sheep and was, in essence, an exact replica of its “mother.” Soon after, groups sprung up from all over the world claiming that, they too, had created clones. A group in Oregon declared that they had cloned monkeys while a Japanese research team professed to have created perfect clones of mice. What followed was a worldwide outcry for the world governments to regulate cloning before it bulged out of control. President Clinton rushed to stop government funding of human cloning research and urged independently financed researchers to stop cloning research until his National Bioethics Advisory Commission, which was founded the previous year, issued their report on the “ethical implications”(Bailey 1) of human cloning. The Committee issued the following statement in May of that year:
The [National Bioethics Advisory] Commission concludes that at this time it is morally unacceptable for anyone in the public or private sector, whether in a research or clinical setting, to attempt to create a child using somatic cell nuclear transfer cloning. The Commission reached a consensus on this point because current scientific information indicates that this technique is not safe to use in humans at this point. Indeed, the Commission believes it would violate important ethical obligations were clinicians or researchers to attempt to create a child using these particular technologies, which are likely to involve unacceptable risks to the fetus and/or potential child. Moreover, in addition to safety concerns, many other serious ethical concerns have been identified, which require much more widespread and careful public deliberation before this technology may be used.
The report was testament to the fact of America’s fear of an unknown and mysterious technology. While cloning’s role in United States law has still not been determined, the government has allowed research into it. Cloning is most definitely a something that needs to be researched further. From increased agricultural production to saving a human life to increasing a standard of living, the possible benefits of what cloning can do for the Human race are limitless.
For years, the agriculture industry’s main purpose has been to feed the world. Now, through cloning, its purpose may change to benefit society in more ways than one. In 1994, a bovine growth hormone known as BST (bovine somatotropin) became available to farmers. The hormone, which is made naturally in the bodies of cattle, was synthetically manufactured in order to boost growth in calves and increase the milk yield of mature dairy cows by 20 percent. (Grace 100). Although feared by many consumers, the genetically engineered hormone was approved and advocated by FDA commissioner David Kessler, who stated, “[BST] has been one of the most extensively studied animal drugs products to be reviewed by the agency. The public can be confident that milk and meat from BST-treated cows is safe to consumers” (Grace 101). The benefits of genetic engineering on animals are not limited simply to hormonal boosts. Eventually, farmers will be able to breed livestock to have certain desirable traits such as disease resistance, lean bodies and increased milk production. This will, in turn, “reduce the costs of vaccination, hormones, and drugs,” (Torr 25) says David A. Christopher, an associate professor in the Department of Plant Molecular Physiology and Molecular Biosystems Engineering at the University of Hawaii. Cloning could also be applied to eliminate certain undesirable traits such as the “mad cow” disease that ravaged Britain’s livestock a few years back (Harley 3).
One large and very important aspect of cloning is its potential to bring endangered animals species back into prominence on earth. The most recent experiment with endangered species had to do with an animal called a gaur. The gaur, a wild boar that is usually found in India and Southeast China, is feared to be nearing extinction because only 36,000 are known to exist in the wild (Lanza 1). Cells taken from the dead body of another gaur were put into the uterus of a dairy cow that became a surrogate mother for a gaur that scientists named “Noah.” Unfortunately, Noah died within two days of its birth from complications due to “dysentery probably unrelated to the cloning procedure,” stated Philip Damiani, a researcher with the team that cloned Noah. However, Damiani went on to state that,” [Noah’s] birth brightens the prospects that we can apply this technology to many species on the verge of extinction.” Of the creatures headed up the “ramp of the ark of endangered species,” (Lanza 1) gaurs are only one of many. Scientists hope to clone endangered species such as the African bongo antelope, the Sumatran tiger and the ever-popular Chinese giant panda. Cloning has become a more approachable solution to the endangered species problem in recent years because of Zoos’ deficiency in being able to reproduce and maintain significant numbers of endangered animals. It is also apparent that most zoos do not possess the equipment to collect and successfully preserve semen; something that is vital to the reproduction process. However, by simply freezing the tissues of a dead animal that is a prospect for cloning, scientists can clone as many animals as they need from that material (Lanza 1).
Many scientists feel that cloning would decrease the biological diversity of a certain cloned species, (i.e.-create a singular and similar DNA pattern among all animals of the same species), which could cause even more problems than its worth. Essentially, if many animals were cloned from the cells of the same dead animal then those animals’ chromosomes would be identical. Thus, if they were to breed naturally in the wild then there offspring would have defective traits rooting from the combination of the two similar chromosomes. An article published in Scientific American by Scientists of ACT (Advanced Cell Technology), the same organization that cloned Noah and is currently working on cloning more endangered animals, states that this is an unfounded fear. The authors say that they “advocate the establishment of a worldwide network of repositories to hold frozen tissue from all of the individuals of an endangered species from which it is possible to collect samples.”(Lanza 4) From these “repositories” scientists could take biologically different DNA samples and thus produce a population of previously endangered animals that would be fundamentally different in their chromosomes. In this fashion, geneticists could slowly repopulate the earth with previously endangered species.
Beyond the bounds of agricultural and endangered species advancement, animal cloning promises some other benefits to save human life. Scientists have long dreamed of being able to breed livestock that would be able to secrete certain human proteins through their milk. This dream was partly achieved in 1990 with the creation of ‘Tracy’, a “transgenic” sheep. This meaning that Tracy’s genome (genetic material) was genetically altered so that she could carry foreign genes. In this case the “foreign genes” that Tracy carried were a human protein named alpha-antitrypsin and it was secreted through her milk. The alpha-antitrypsin that was in Tracy’s milk is a useful protein for emphysema because a deficiency in this protein is what causes the airways of emphysema sufferers to be blocked (Ho 160). Also, by cloning transgenic animals that carry a protein which causes clotting in human blood, we would be able to “mass produce these proteins for clinical use for hemophiliacs or during surgery”(Gardels 1). Although research with transgenic animals is far from conclusive and has offered little usable results, its future is bright.
A more practical and much more real application of animal cloning is xenotransplantation, which is known as cross-species tissue or organ transplantation. Essentially, certain animals such as pigs can be cloned and their organs can be harvested in order for them to be introduced into the body of a human that is in need of that type of organ. In fact, this type of surgery was used in 1992 when a man dying of hepatitis had a baboon’s liver transplanted into him (Grace 60). This type of surgery, however, has been ignored for many years because of the health risks to humans receiving non-human organs; the U.K banned xenotransplantation because of this. The human body attacks any material that is foreign to it and thus a foreign object, such as a pig heart, that is being put into a patient will be rejected by the human T-cells (Ho 181). Fortunately, through genetic engineering, this problem can be completely eliminated with some further research and time. In 1994, according to Eric Grace, “pigs were engineered with human genes so that their tissues produced human proteins that inhibit organ rejection” (60). The market for human organs is large and may be worth, “ $ 6 billion per year in the U.S alone.” Already, biotech companies such as Imutran, a Cambridge based company that leads in producing pigs with human genes, have popped up all over the world (Ho 180). Animal cloning science is, as of yet, a generally hypothetical technology with many gray areas. However, animal cloning has extremely useful connotations that can not be overlooked.
While much of the public attention has been focused on the potential horrors of human cloning, many people are unaware of the hidden possibilities of gene cloning. By gene cloning, scientists mean the manipulation of the human blueprint; the gene. Genes have been a mystery to scientists for years, while they seem to hold the answer to why the human body has the robustness that is does, the human gene also seems to be the downfall of the human body. Many crippling and often times fatal diseases such as Tay-Sachs Disease, Parkinson’s Disease, Cystic Fibrosis and Downs Syndrome are clearly related to defective human genes being passed down from generation to generation in the mitochondria. Cloning may hold the key to a cure for some of these debilitating diseases. The reason that a genetic disease is so crippling is because the human system is unable to produce certain chemicals because of a defective gene coding, chemicals that are necessary for the human body to function normally. Often times, a child might inherit a genetic disease from parents who do not have that particular disease at all. However, if both parents have a defective gene, they can pass a disease on to their children without even knowing it (Grace 39). “Gene Therapy” as it is known was first employed in 1990 with a rare disease that was caused by the lack of a human enzyme known as ADA (adenosine deaminase). People who lack a normal level of this enzyme are at a high risk of early cancer and many die early in life. Scientists learned that by injecting a normal ADA gene into human T-cells that lacked ADA, that the enzyme’s production was boosted by 25% in these defective cells, “more than enough to correct the conditions caused by ADA deficiency,” (72) stated science writer Eric Grace in his book “Biotechnology Unzipped.” Bio-scientists then used this new technology on sufferers of ADA deficiency who, with a “regimen of infusion with ADA gene-corrected cells every one or two months,” drastically improved.
The key to eliminating genetic disorders in some cases is in targeting these defective genes and fixing them before they can form into a genetic disorder. Instead of supplementing the human body with something that it is lacking, gene therapy can sometimes block something from the human body that it doesn’t need. This approach to gene therapy, called “antisense therapy,” focuses on repairing a defective gene that causes trouble for the human body. In antisense therapy “scientists add a gene that mirrors a [defective gene] to a troublesome gene, [that binds] onto it and blocks its action” (Grace 74). Basically, if a defective gene is producing a negative protein, then antisense therapy can prevent this harmful protein from being formed and allow for normal production of proteins.
Thousands of people die every day because of the terminal malfunction of a vital organ. Although most peoples’ lives can be prolonged through surgery such as organ transplantation, the simple fact is that there aren’t enough spare body parts to go around. In 1997, the American Heart Association reported that “only 2,300 of the 40,000 of Americans who needed a new heart got one” (Mooney 1). An exciting new promise of gene cloning is something that scientists have called “neo-organ production.” A neo-organ is an organ engineered completely from scratch, independent of a human body that can replace a damaged organ. “The idea is to take individual cells from a tissue or organ and seed them in a fine mesh of soluble material, then incubate them until they multiply and connect up,” says Eric Grace. The main reason for this is that the human immune system, as stated before, is made to reject anything that it deems a germ, in this case, foreign tissue. This is why many early transplantation attempts failed because doctors didn’t realize that you couldn’t just transplant any organ into the human body because it will, ultimately, be rejected if the blood and tissue type is different. This is another major reason why many awaiting transplantees die; not only are there not enough spare organs to go around but the few available organs need to also comply with a patient’s individual system or they are useless. Scientists have learned that this slow and often times fatal search for an adequate organ can be bypassed through cloning. For example, victims of Leukemia often time die because an adequate donor of bone marrow can hardly ever be found. However, by cloning the bone-marrow cells of that patient, new material can be given that would save their life. Unfortunately, this facet of cloning is the one that has had the most trouble being accepted by the public because of its ethical implications. Right now, scientists don’t have the technology to simply clone a person’s individual cells; they must rely on “stem cells.” These are cells that are capable of becoming any type of tissue in an organism (Wilmut 53). By isolating stem cells and then manipulating them, scientists could turn a stem cell into whatever kind of cell they desired. The main concern of Stem Cells is not an issue of what significance they have but rather of their origin. What scientists do currently is take healthy cells from a patient in need of an organ, remove the genetic material from their cells and put it into an empty egg. The egg would then begin to form into an embryo (actually a clone of the person whose cell was used) and begin to divide into the different types of cells that make up the human body. These early embryonic cells, which are stem-cells, could then be transformed into whatever material is needed such as skin cells for burn victims in need of a skin graft or kidney cells for people in need of a kidney. This is where the problem lies in many peoples’ eyes because a human embryo is killed in order to harvest its stem cells. So the question is “When exactly does an embryo become a person?” Britain, which legalized Stem cell research in January of 2001, believes that “at about three or four days old, before the cells have started to specialize to create a nervous system,” is the window before human life actually begins (Ross 2). Still, Britain is the only country to completely legalize cloning for medical purposes and will probably be the only one to actually do so for many years to come. In the United States, “political fear of the religious right is what’s holding [stem cell research] back and it will continue to hold it back,” stated Glenn McGee, a bioethicist at the University of Pennsylvania and editor-in-chief of the American Journal of Bioethics (Ross 1). Already, California and Rhode Island have completely banned stem cell research and many states have similar legislation in the works, although a bill on a national ban of cloning was shot down in 1998. In addition, 19 European nations have signed anti-cloning treaties (Nash 1).
What the world must realize is that cloning holds many additional benefits than the ones outlined above, it is truly a technology with so much hidden potential that it would be unethical not to continue research into it. However, we as a society must also realize that the basic idea of cloning is not a new one; the idea of giving “synthetic” life that wasn’t given by nature. When scientists introduced the idea of early organ transplantation, many people feared for the future of human kind, but organ transplantation has now become a necessary and excepted part of medical practices. As long as humanity acts sensibly, we can avoid all of the fears that people have of cloning and realize its potential as not a scientific horror but as a scientific miracle.
Bailey, Ronald. “The Twin Paradox.” Reason, May. 1997:22-26.
Gardels, Nathan. “ The Limits of Cloning.” New Perspectives Quarterly 5 (Fall 1999): 10-13.
Grace, Eric S. Biotechnology Unzipped: Promises and Realities. Washington, D.C: Joseph Henry Press,1997.
Harley, Calvin. “Cloning: Techniques and Applications in Human Health.” Generations, Spring 2000: 65-71.
Ho, Dr. Mae-Wan Ho. Genetic Engineering: Dream or Nightmare? Bath, UK: Gateway Books, 1998. Explains ethical issues behind cloning. Excellent source for information.
Human Cloning Foundation. “The Official Site in Support of Human Cloning.” February 26, 1996. www.humancloning.org. Date of Access: February 7, 2001. An insite into cloning. Reveals all of the intricacies of genetics, many facts. Also includes bookmark to a page of recent cloning-related issues.
Lanza, Robert P. “Cloning Noah’s Ark.” Scientific American, November 1, 2000.
Mooney, David J. “Growing New Organs.” Scientific American, April 1999: 60-65.
Nash, J. Madeline. “The Case for Cloning.” Science, Februaury 9. 1998: 56-57. Provides a clear, un-biased case for why cloning should be legalized.
Ross, Emma. “Ethicists say Abortion Issue Tempers U.S Embryo Research.” Associated Press, January 24, 2001.
Torr, James D.,ed. Genetic Engineering: Opposing Veiwpoints. Ssan Diego, California: Greenhaven Press, Inc., 2001.
Wilmut, Ian. The Second Creation. New York: Farrar, Straus and Giroux, 2000.
- ... .” These ideas are far fetch and misunderstood. Human Cloning is inevitable. The United ... be paid back when cloning is further research and cloning becomes an optional ... came Americans truly benefit from cloning and medical revolution that this technology ...
- ... , goats, and primates (Cloning Firsts). Recently, human cloning has become ... breakthrough in human cloning, and this one has come ... down to. Cloning is unknown and misunderstood so people shun ... the idea. Of course, if cloning ...
- ... idea of cloning because it is new and misunderstood. There is ... are many benefits to cloning and since not everyone believes ... there are laws prohibiting cloning and its research. Another benefit ... Many people do support cloning and whether the government makes ...
- ... seem to most fear is cloning. Specifically one of my ... a debate about cloning and the side against cloning stated that if ... when it comes to cloning and gene therapy. And what they think ... Probably one of the most misunderstood technologies is the Internet. Some ...
- ... One of the most underrated and misunderstood of all film genres, the ... market as Bruce Lee prot?g?s/clones in an apparently unending series ... Chaplin and Buster Keaton, alongside a Bruce Lee-inspired intensity. Totally misunderstood as ...