MadSci Network: Genetics
Query:

Re: What are is the reason for cloning???

Date: Mon Feb 23 14:04:04 1998
Posted By: Dan Berger, Faculty Chemistry/Science, Bluffton College
Area of science: Genetics
ID: 885930459.Ge
Message:

What does cloning do for us and animals?

Cloning has some value for plant and animal husbandry. It has been practiced in horticulture for a very long time: plants grown from cuttings are clones. Growing a plant (especially a tree) from cuttings speeds up the reproductive cycle tremendously, and ensures that desirable traits are exactly reproduced in the next generation.

In the 1950s, F.C. Steward first demonstrated totipotency, the principle that every cell contains the instructions for reproduction of an entire organism, by taking the technique of growing cuttings to an extreme. He carefully puréed a piece of carrot into individual cells, then grew an entire carrot plant from one of the cells. All subsequent cloning experiments, both with plants and with animals, have been based on this principle, and vertebrate animals were first cloned in 1970, when John Gurdon got tadpole genes to run the show in unfertilized frog eggs.

In animal husbandry, cloning is a way of ensuring the exact reproduction of a desirable genetic trait. Even inbreeding is not as good for this as cloning, in which the entire genome is duplicated. For most animals, such exact reproduction is not important; but I give examples below of situations where cloning would be quite useful.

In the current state of the art, cloning is inefficient. Dolly, the first mammal cloned from nuclear material taken from an adult animal, was the result of one success in about 500 tries. A new technique, about which news has just appeared, claims to have brought the efficiency to about one success in 50 tries. The efficiency is likely to improve in the future, though cloning will probably remain a rather expensive way of breeding animals.

Cloning would be worthwhile for animals which have been genetically engineered, at great expense, to produce valuable substances in their milk or urine (an example is human clotting factor, for treatment of hemophilia). The technology is also being investigated for the production of genetically identical laboratory rats, which would be useful in biomedical research, especially when the original genome carries some desirable trait (such as having one particular gene "knocked out," so that the effect of that gene can be investigated).

Cloning is being considered as a means of helping infertile human couples have babies. This is arguably OK from an ethical standpoint, though in my opinion a shameful waste of resources.

There is the remote possibility that someone may clone her/himself as an act of egomania, and try to make the clone a carbon copy of the parent. This is no argument against the technology itself, but the rights of the clone (who, after all, would be a human being) should be scrupulously protected.

Remember, human clones are nothing new. In fact, you probably know some clones. Identical twins are clones of each other; both of them came from the same fertilized egg cell. Yet they are not duplicates of each other; each twin has her/his own personality.

A timeline of vertebrate cloning is available. If you are interested in the ethical issues related to cloning, here are starting points from the Church of Scotland's Science, Religion and Technology Project:

For a more irreverent view, you might try Dolly's Cloning Emporium.

  Dan Berger
  Bluffton College
  http://cs.bluffton.edu/~berger


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