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Introduction

Review and discuss the significance of animal cloning (such as: Dolly the sheep) Animal Cloning is the production of one or more identical copies of a genome of a particular animal. Embryo splitting (or blastomere separation) and nuclear transfer are two methods by which animals may be cloned. Both of these methods require gestation in the uterus to attain complete development. Embryo splitting is the process whereby an embryo has its cells (blastomeres) separated soon after fertilization at the 2nd, 4th or 8th cell stage. At this stage, each cell is considered to be at a stage where the genetic material has not been programmed to develop into a select tissue, it is undifferentiated and can therefore develop into a variety of tissues, or a complete organism given the correct conditions. This is referred to as totipotency and it allows scientists to split animal embryos into several cells to produce multiple organisms that are genetically identical. Modern techniques begin with stripping the embryo of the protective layer. After each blastomere has been separated from the embryo mass, the cell is encased in its own protective synthetic layer. Each blastomere cell, is now considered a new separate embryo and is cultured in vitro and later in vivo in a surrogate mother until birth (Roberge, 2004). Cloning by nuclear transfer is based on the concept that the animal's genome is located in the cell nucleus. The only exception to this is the small amount of DNA of 16, 000 base pairs found in the mitochondria. ...read more.

Middle

Another aspect of cloning that would be beneficial is the interest in producing pigs whose genes have been altered to produce a component of the human immune system's regulatory proteins. The process of using animal organs for human organ transplantation is called xenotransplantation. This would make pig organs more suitable for human transplantation. Such treatments are in progress, for example, heart valves of pigs in treating humans with malfunctioning hearts. Cloning by nuclear transfer could also help generate gene alteration in animals much more efficiently. This would be of great significance for research in genetics and gene therapy. Introducing specific mutations in mice, called "knockout mice," has been an important way to study the effects of certain genes. Producing such animals requires that embryonic stem cells are altered in culture to produce a blastocyst, which is then placed in a surrogate. The resulting animal must then mate again to produce germline transmission of the altered stem cells. Cloning would allow the genes of large mammals to be altered in this way while accelerating the traditionally long generation and litter cycles. Another means by which animal cloning can aid in research is in the efficient production of genetically identical animals. The production of these genetically identical, homozygous animals will aid in the elimination of genetic variation as a confounding variable in experiments. With nuclear transfer cloning, a single blastocyst can be used as the source of donor nuclei for subsequent blastocyst, which in turn can serve as donor nuclei. ...read more.

Conclusion

Concurrently, researchers are already "modifying the genetic structure of animals in order to study illnesses and to generate human proteins and antibodies"(Wilson 463 cited by Nguyen, Peter n.d). Cloning has benefits ecologically in that populations of rare endangered species may be saved. Nuclear transfer and techniques such an "embryo cloning" could contribute to the preservation of endangered species such as the Sumatran Tiger. Around the world scientists have begun collecting and storing frozen tissue samples of endangered animals for which cloning could prove to be a last resort. Work has already progresses towards cloning the Sumatran Tiger and China's Giant Panda using the same technology that created Dolly the sheep. Although cloning has many benefits, there are also many biological disadvantages. One such biological problem is the high mortality rate, however it is said that with greater understanding of what determinants cause the death of clones, the mortality may decrease. Another biological problem is the decline in species diversity. Ethical issues also arise which need to be addressed. There are numerous applications that nuclear transfer cloning might have for biotechnology, livestock production, and new medical approaches. Work with genetic manipulation and embryonic stem cells provide many pharmaceutical proteins and prospects for regeneration and repair of human tissues. Referneces Nguyen, P. Cloning, ethics, what lies ahead. http://cseserv.engr.scu.edu/StudentWebPages/PNguyen/ResearchPaper.htm (Maech 19, 2005) Van Eenennam, A. (n.d) Livestock Cloning. http://animalscience.ucdavis.edu/animalbiotech/Outreach/Livestock_cloning.pdf (March 21, 2005) Roberge, L. (October 18, 2004) Cloning: Scientific, Technological and Ethical Considerations. http://www.changingworldviews.com/GuestCommentaries/LawrenceRobergearticle2.htm (March 21, 2005) Anon. (n.d) The science and application of cloning. http://www.georgetown.edu/research/nrcbl/nbac/pubs/cloning1/chapter2.pdf (March 20, 2005) History- http://www.roslin.ac.uk/public/01-03-98-nt.html Anderson B. et al. (2002) A Guide to Modern Science:Science and Technology in Today's World, pp 112-115, Cloning, Fog City Press, San Francisco,CA ...read more.

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