本文发表在 rolia.net 枫下论坛One benefit of cloning human tissue is that if we can grow vital organs, they can be used to replace ailing organs. For example, if heart disease destroys a patient's heart, an exact replica can simply be "grown" to replace it.
There are several advantages to the cloning of animals and to the cloning of human cells. Along with each of the advantages, however, there are disadvantages, risks, and warnings.
There are five important reasons why animal cloning might be useful: (1) to generate groups of genetically identical animals for research purposes; (2) to rapidly propagate desirable animal stocks; (3) to improve the efficiency of generating and propagating transgenic livestock; (4) to produce targeted genetic alterations in domestic animals; (5) to pursue basic knowledge about cell differentiation.
Cloning animals for research purposes is attractive to many scientists, because the experimental variation that often occurs with genetic differences is eliminated. This process is limited in its usefulness, however, because keeping a homozygous line is going to be difficult. Also, the overall process promises to be expensive for most animals.
Having a speedy method to breed favorable livestock has great commercial importance. Nuclear transfer may be the wave of the future to rapidly produce desirable stocks of animals. The ultimate consequences could be dangerous, however, because genetic diversity could be eliminated. Strict regulation of cloning would ensure that this would not happen, though.
The improved generation and propagation of transgenic livestock becomes of interest to the pharmaceutical and medical world. Genetically altering farm animals by the introduction and expression of genes from other species proves to be a useful technology for the future. For example, the milk of livestock animals can be modified to contain large amounts of pharmaceutically important proteins such as insulin or factor VIII for treatment of human disease by expressing human genes in the mammary gland. Also, transgenic animals could become useful for organ transplantation into humans.
Generating targeted gene alterations in domestic animals can be helpful in studying mutations of genes in a very controlled manner. Gene targeting approaches can also be used to ensure correct tissue-specific expression of foreign genes and to suppress the expression of genes in inappropriate tissues. It could also be used to directly alter normal genes, which could influence animal health and productivity.
Basic research on cell differentiation has come about with the arrival of Dolly. Developmental biologists will want to know which genes are reprogrammed, when they are expressed, and in what order. This may or may not shed some light on the specialization that occurs during the development of therapies to treat human disease.
The agricultural industry could reek the benefits of this new technology by having the ability to produce multiple identical copies of a cow that produces a lot of mile, a sheep that produces a lot of wool, and so on. They could create an elite stock of farm animals.
The most exciting prospect here is to modify a sheep CTFR gene to create a model of cystic fibrosis (CF) for gene therapy. In a classy move, Ian Wilmut sold the first wool shorn from Dolly to raise money for the care and treatment of kids with CF.
There are five potential uses for cloning humans or human cells: (1) a research tool to understand how genes in cells can be switched off and on; (2) growing new skin for burn victims; (3) culturing bone marrow that could be used to treat cancer patients; (4) manipulating genes to cure sickle cell anemia; (5) potential application in treating infertility.
A more controversial benefit is to provide children for lesbian couples. Normally they need an outsider to donate sperm; with cloning they would be able to avoid this.
There are several disadvantages associated with cloning, such as significant scientific uncertainty, medical risks, potential effects of aging, somatic mutation, and improper imprinting. A cloned child is not really a couple’s genetic child, but the child of only one of them. That imbalance may produce strains on the marriage the child might suffer identity confusion, and there is a risk of perpetuating the cause of sterility.
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Human cloning can also be a solution for infertile couples, even allowing the couples to create a child with certain features. Because cloning allows for the manipulation of genes, embryos can be created free of inherited genetic disorders or predispositions.
The cloning of human tissue could also be used to treat cancers, and even for plastic surgery.更多精彩文章及讨论，请光临枫下论坛 rolia.net