Cloning

Will

The History of Cloning


The theory of being able to make a genetic copy (a clone) of another animal has been around for quite a while. In this section as the title reads I will show the history of cloning.

400 million years B. C.- Plants have been cloning themselves since not to long (as far as the Earth is concerned) after their introduction to our planet. They send out runners that create an identical copy of the parent plant.

1938- Hans Spermann, of Germany, envisions what he calls the "fantastical experiment". He suggests taking the nucleus from a cell in the late-stage embryo and transplanting that nucleus into an egg.

1952- Scientists Robert Briggs and T.J. King use a pipette to suck the nucleus from the cell of an advanced frog embryo, they then add it to a frog egg. The egg didn't develop.

1970- John Gurdon tries the same experiment with the same procedure. The eggs developed into tadpoles but died after they were ready to begin feeding. He later showed that transplanted nuclei revert to an embryonic state.


1973- Ian Wilmut just finishes his doctorate at Cambridge University when he produces the first calf born from a frozen embryo. Cows only give birth to five to ten calves in a lifetime. By taking frozen embryos produced by cows that provide the best meat or milk then transferring that to surrogate mother it allows cattle farmers increase the quality of their herd.

Mid to late 1970's- Scientists cut down small forests publishing research papers arguing the ethics of cloning and if it can be done. While they do this other researches around the world are actually investigating if it can be done.

1981- Karl Illmensee and Peter Hoppe report that they clone normal mice and embryo cells. It is later found to be a fraud.

1982- James McGrath and Davor Solter report that they can not repeat the mouse cloning experiment. They conclude that once mouse embryos reach the two cell stage they cannot be used for cloning. Others confirm their results.

1993- Embryologists at George Washington University cloned human embryos: they took cell groups from 17 human embryos (defective ones that an infertility clinic was going to discard), all two to eight cells in size. They teased apart cells , grew each one in a lab dish and a few got to 32 cells- a size when they can be planted into a surrogate mother, although they weren't.

1994- Neal First cloned calves that have grown to 120 cells.

1996- Ian Wilmut repeated First's experiment with sheep but put embryo cells into a resting state before transferring their nuclei to sheep eggs. The eggs developed into normal embryos then into lambs.

1997- Ian Wilmut and his colleague Keith Campbell clone an adult sheep.
Different Methods: Of Cloning


The most famous sheep in history, Dolly, was cloned by using the method of Nuclear transfer. Previously the only cloning was either done on plants or frogs or mice. In this section the different processes will be described.

PLANT CLONING
Gardeners have been cloning plants for centuries and plants have been doing it for longer. Here are three different types of cloning out of many. One type of plant cloning naturally occurs when a plant grows a runner. The runner grows horizontally across the ground forming a carbon copy of that same plant at the end. Eventually the runner dies and the daughter plant is separated from the mother plant. Another is when you cut a branch or leaf off of a plant and plant it. It will grow another identical plant. That method is called a cutting. A stolon is where a weak branch of a plant falls over and the tip touches the ground. The tip swells and roots are formed so that growth in the plant can continue.

ANIMAL CLONING
Lower forms of animals clone themselves quite often like amoeba's and paramecium which use binary fission to split themselves in half and create a new but identical animal.

The only other kind of cloning in animals is nuclear transfer cloning. Which is the whole topic of this report.
Nuclear transfer is when the nucleus of one cell is implanted into another cell that has had the nucleus taken out. The first time this happened was when Robert Briggs and T.J. King took the nucleus out of a multi-cell embryo and implanted it into the egg. Cell division then takes place and forms into