Cloning, the process of Manipulating a cell from an animal so that it grows into an exact duplicate of that animal is the forbidden fruit of biology. (Begley 54). The word clone, derived from the Greek word Klon, meaning twig or slip, refers to asexual reproduction. Also known as vegetative reproduction. Cloning became known to the public about 30 years ago. This idea of cloning about his time resulted in an experiment of the successful asexual reproduction. This experiment took place in England, where a whole bunch of tadpoles was cloned by the technique of nuclear transplantation.
Nuclear ransplantation refers to the process of moving a nucleus from one cell to another. (Mckinnel 28) The person responsible for this introduction of cloning was Joshua Lederberg, a noble laureate geneticist. (Kass, Winters 9) Scientists have known for a long time what it took to clone, and many had found themselves believing that it was biologically impossible. One problem was the way the embryo develops. Every cell in the body comes from the same fertilized egg therefore, every cell in the body contains the same genes.
But animal and human cells are specialized and different, so that a heart cell acts s a heart cell and a liver cell acts as a liver cell. This specialization starts when the fetus is formed, and once a cell reaches its final state, it never changes. A brain cell will always be a brain cell as long as a person is living, it would never change into a liver cell although it contains the same genes. (Kolata 24) Frogs were the first multicellular animals to be cloned in the 1950s. A thorough cloning experiment produces a frog asexually.
No gamete nucleus, sperm or egg, participates in the development of a frog that is truly a clone. (Mckinnel 3) The cloning procedure in frogs, toads, and salamanders is very difficult. In order to start this cloning process, the ability to obtain eggs and sperm from frogs had to be introduced. Also the process of vitro fertilization, removal of maternal chromosomes from eggs, and the splitting of embryos into individual cells. (140) To obtain frog eggs, the eggs have to grow to their maximum size and the frogs are ready for hibernation under the ice of lakes and streams.
Ovulation can be induced from September to or past the time of natural ovulation. Eggs leave the ovary, move to the reproductive tubes, and become available to the embryologist when the female frog is injected with pituitary lands or a combination of pituitary glands and the hormone progesterone. The eggs can be removed from the female after this treatment by gently squeezing the abdomen. (41) Frog sperm can be obtained by cutting the testes of the frog into small pieces in a diluted salt solution. The testes are dissected from the male, which usually requires sacrifice of the frog donor.
Then, a commercially available hormone present in pregnant humans, is injected into a mature male frog. Within one hour, millions of sperm are released from the testes of the frog and found in the frogs urine. This sperm is then capable of fertilizing frog eggs. (41-42) Eggs and sperm can be combined in a glass dish at a precise time. By caring for the fertilized eggs at a particular temperature and time, donor embryos of predetermined stages can be obtained. Using glass dishes is a simple and efficient way of producing the frogs since frog eggs are very large and contain an immense amount of stored food. 42)
The next step to the cloning of frogs is to prepare the frog eggs to receive a transplanted nucleus. Freshly ovulated eggs have the same amount of DNA as an ordinary body cell. That amount of DNA is twice the amount found in a sperm; so it is called diploid. A sperm contains the haploid amount of DNA. The fact that the ovulated eggs are diploid, helps with the experiment greatly. If diploid eggs could combine with diploid sperm, than the amount of DNA in the offspring would become enormous in only a few generations, but this does not happen.
What happens is that the frog egg becomes haploid as the sperm already is, after it is released from the ovary and at that time it is activated by the penetration of the sperm. This results in an egg devoid of any genetic material in the form f chromosomes. This egg only has to be removed from the jelly envelope that surrounds it by cutting it with scissors, in order for it to be ready to be transplanted in to a nucleus. (42-43. ) After the jelly envelope is removed from the egg it is placed in a solution that separates each individual cell of the egg.
The surgery that is needed to be performed involves using micropipettes, microinjection apparatus, and micromanipulation equipment. This micropipette is a glass tube that is positioned adjacent to the one cell selected from the many cells with the microinjection apparatus. The donor cell is then drawn into the micropipette with the microinjection apparatus, which is a machine that holds a tool very steady, and allows small precise movements of that tool. When the cell enters the opening of the micropipette, the cell membrane is ruptured and there is slight leakage of its cytoplasm.
The cell membrane is very thin but extremely important. (43-46) If the membrane is left on the inserted donor cell, the ovum with its donor cell cannot develop. However, a donor cell with its nucleus apart from the membrane can come together with the egg cytoplasm to start the evelopmental system-which sometimes results in the formation of a frog. (46. ) The process of cloning frogs took very long to do and was often very unsuccessful. (Cohen 13) Twenty years ago, when only the lowly tadpoles had been cloned, bioethicists raised the possibility that scientists might someday advance the technology to include human beings as well. Woodward 60) In 1978, the infertility revolution began.
Louis Brown, who was born in England, was the worlds first test-tube baby. Scientists had learned to fertilize womens eggs outside their bodies, allowing human life to start and take place in a petri dish in a laboratory. Kolata 11) In 1993, embryologists at George Washington University cloned human embryos, they took cells from 17 human embryos, (defectives ones) they then teased apart the cells, grew each one in a lab dish and got a few 32-cell embryos, a size that could be implanted in a woman. Begley 55) One of the greatest cloning experiments ever accomplished was the production of Dolly.
Scientist Ian Wilmut used several techniques learned from his research group and others to clone a sheep and make Dolly. Keith Campbell, his colleague, sucked the nucleus out of an egg that was taken from an ewe. This created an egg ith the absence of genes that would die without its nucleus. So he began the process of putting the nucleus of an udder cell in to the egg. (Kolata 21) He slipped the udder cell underneath the outer membrane of the egg. Next, he hit the egg for a few small seconds with bursts of electricity.
This opened the pores of the egg and the udder cell so that what was in the under cell, including chromosomes would go into the egg and remain there. Now the egg had a nucleus shared by the udder cell. The electricity made the egg act as if it were fertilized. ( 27) After 21 times of repeating this experiment, Wilmut and his olleagues had managed to create this frisky little lamb name Dolly. Dolly does not resemble her biological mother, she is an exact copy or replica of her mothers identical twin. (Nash 62). Dolly was born on July 5, 1996 at 5:00 p. m. he was the most famous lamb to enter the world and a creation that would change the world forever. She was born in a shed, just down the road from the Roslin Institute, in Scotland where she was created.
She weighed 6. 6 kilograms, or 14. 5 lbs. (Kolata 1-2) Although the cloning of Dolly was a great success, it was a very frightening ask, but it soon became a question on everyones mind. (Kolata 10) Roslin researchers struggled for 10 years to achieve their breakthrough. Finally, political and religious leaders around the world grasped the concept that if scientists can clone sheep, they can probably clone humans too. Nash 62). Many different concepts of cloning have been considered since it is such a very controversial issue. Some views discuss why cloning would serve the world with answers to the questions asked and possibilities thought of, while others feel cloning is just a way of making the world even more confusing than it lready is.
The ability to clone adult mammals, in particular, opens up numerous exciting possibilities; from propagating endangered animal species to producing replacement organs for transplant patients. Nash 63) The government could put a restraint on the cloning of human beings and they can also issue regulations that limit the work researchers can do. But the government cannot stop people or groups of people that want to clone humans. Now the cloning of humans is within reach and society as a whole is caught with its ethical pants down. (Woodward 60) Muslim Scholar Aldulaziz Sachdina, a medical thicist at the university of Virginia, asks Imagine a world with no need for marriage. 61)
The study of cloning can give the world deep insights into such puzzles as spinal cords, heart muscle & brain tissue that wont regenerate after injury, or cancer that reverts to embryonic stage and multiplies Uncontrollably. (60) Its a horrendous crime to make a Xerox of someone, argues author and science critic Jeremy Rifkin. Youre putting a human into a genetic straitjacket. For the first time, weve taken the principle of industrial design quality control predictability and applied then to a human being.
