Example research essay topic: Transgenic Animals Human Cloning - 1,487 words

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... ls with an apparently desirable genetic constitution. If Dolly represents one genetic copy of her mother then nuclei from the thousands of other udder cells could, with a sufficient supply of host eggs, produce a thousand Dollies - a thousand genetic replicas - in a single generation. However, here theory and practice diverge. Dolly was a single sheep produced from nearly three hundred attempts, without even counting the previous years of failed experiments. With a single result of this kind it is not possible to evaluate the real frequency of success.

Is it one in three hundred or one in a million? Recently, the newspapers have published accounts of a second sheep clone, although for reasons of commercial priority the provenance of this clone has not been made available to scientific scrutiny. The existence of a second clone at least suggests that there must be a finite chance of obtaining live born sheep clones. Nonetheless, cloning remains an extremely costly, technically demanding and inefficient exercise; not one poised to replace normal methods of animal husbandry. The desire to clone livestock is largely allied to trans genesis: the ability to add new genes to an animal's normal repertoire or to precisely modify one of its own genes. Why would one want to do such a thing?

One reason is that farm animals could then be used not just to provide traditional products such as meat, milk and hide but also to produce natural proteins for pharmaceutical use, or to serve as organ donors for human transplants. Of course, the production of drugs from animals is not new - hundreds of thousands of pigs have been sacrificed over the years to supply diabetics with insulin. However, trans genesis offers a more imaginative and less destructive way of producing drugs from the farm. Transgenes have been introduced into the nucleus of cow, sheep and pig eggs and become part of the resulting animal's genetic repertoire, indistinguishable as far as it is concerned, from its own genes.

Such genes have been designed to cause secretion of human proteins into the milk, thereby turning the milking parlour into a drug production line. In this way, animals have been generated whose milk contains human proteins involved in emphysema and blood clotting deficiencies, and it has been possible subsequently to purify quite large quantities of these therapeutic products from the milk. Such transgenic farm animals would allow patients to be treated with 'on tap' human products, and the transgenic animals themselves would enjoy exactly the same life style as any other dairy animal. However, introducing genes into eggs is a rather hit and miss affair, because there is no control over whether the gene will land up in a position where it can be fully active, and only some of the offspring produce reasonable amounts of human protein in their milk.

If the high level producers could be cloned then standardised herds could be established relatively quickly to facilitate efficient drug production. Even better, if animals can be cloned from udder cells then why not introduce the transgene into these cells first, check out that it works properly and then clone an animal from the cell in which the gene is most active. Better still, take advantage of the animal's own mechanisms for ensuring high levels of protein in the milk and replace the gene which codes for one of its normal milk proteins with the gene encoding a pharmaceutical protein. Such precise replacement of one gene by another is possible but extremely inefficient, occurring perhaps only in one of a million cells.

One cannot contemplate generating a million animals on the off chance that such a replacement might have occurred, but it is relatively easy to grow a million udder cells in a dish and to recognise and recover the single cell in which the desired gene replacement has happened. To be able to clone an animal from such a cell, in which a human protein is being produced at the same high levels as a normal milk protein, would permit a much better and more controlled means of making transgenic animals than is practised at present. Likewise, if animals are to serve as organ donors for humans then gene replacement combined with cloning would allow some of the animal genes most responsible for graft rejection to be replaced with compatible human ones. Whatever one's personal views about using animals as vehicles for human drug production or as a source for replenishing defunct human organs, it is important to realise that it is mammalian trans genesis, which has been underway now for twenty years, and not cloning, that has opened the way for such practices. Cloning would have little future, and certainly be of little commercial value, without genetic engineering. Finally, the inevitable question.

Is it possible to clone humans? Actually, the question is unanswerable. Until Dolly came along no mammal had been cloned by transferring a nucleus into an egg. Quite considerable efforts had been made over several years to clone mice in order to understand how gene activity changes during embryonic development.

None met with success and it was acknowledged that cloning mice was not going to be straightforward. One reason why sheep, a far less well understood and less used experimental animal than mice, should have proved easier to clone may relate to differences in the very earliest stages of mouse and sheep embryonic development. The unfertilized eggs of all mammals accumulate a supply of proteins, and the means of making more protein, as they mature in the ovary of the mother. In this way, the egg brings with it a larder for the embryo to make use of until the embryo's own genes become active and it can supply these things for itself.

The sheep embryo makes good use of this store and does not start to depend on its own genes until the sixteen-cell stage, four cell divisions after fertilisation. In contrast, the mouse embryo gets off to a very quick start, becoming reliant on the activity of its own genes after just the first division when the fertilized egg becomes two cells. Therefore, a foreign nucleus introduced into a sheep egg has a bit of breathing space to adapt to its new role before it has to start running the show. On the other hand, a nucleus introduced into a mouse egg has to acclimatize very fast for its genes to be able to direct embryonic development within one cell division. Perhaps there is just not enough time in the mouse for the extensive re-programming of gene activity that is required. The human embryo is thought to rely on its own genes after three cell divisions, when it comprises eight cells.

This might or might not provide time enough for a foreign nucleus to feel at home. However, were we to understand the nature of the re-programming that has to take place then there is every likelihood that both mice and humans could be cloned, although probably still with a very low success rate. In order to be prepared it is probably best to assume that the cloning of humans is not impossible. As has already been pointed out the technology has been available for decades had anyone wanted to try, but apart from the odd bogus book claiming to be an authentic account of human cloning it does not seem that anyone has. The great desire for vanity cloning appears to be a fiction. Are there any arguments in favour of permitting human cloning?

Not many. A handful of people who are childless due to rare hereditary diseases would be able, if they were lucky, to produce offspring that were genetically theirs. However, if Dolly is anything to go by then a success rate of less than one in a hundred poses formidable practical problems. More importantly, it is quite possible that cloned individuals will turn out to be at risk. We do not know the long term effects of asking an 'old' adult cell nucleus to begin life again in an egg. The nucleus of a skin cell could have accumulated many genetic mistakes of no consequence to its role in the skin, but when asked to make a brand new organism these could prove deleterious in other tissues, or greatly increase the probability of developing cancer.

However, if one asks what threat could cloning pose to general human health, as opposed to the individual, then the answer has to be none. The risks are almost certainly lower than those encountered in the effective inbreeding of consanguineous marriages. There are no scientific grounds per se for banning cloning. Like other things which are possible, not of great consequence to the physical well being of humanity, but generally considered undesirable on moral or social grounds, for example cannibalism, female circumcision and polygamy, the outlawing, qualified or not, of human cloning requires a simple pragmatic decision.

Research essay sample on Transgenic Animals Human Cloning