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Some people also have expressed interest in having their deceased pets cloned. However, the cloned pet may not turn out exactly like the original whose DNA was used to make the clone.
In 1963, Chinese scientists reportedly created the first cloned fish by transferring the DNA from a male carp into the egg of a female carp.
Gene cloning produces copies of genes or segments of DNA. It's also known as DNA cloning, and it's a very different process from reproductive and therapeutic cloning.
In 2021, scientists announced that for the first time they cloned an endangered American animal. It was a black-footed ferret named Elizabeth Ann, whose cells were taken from an ancestor.
In 1997, scientists revealed that Dolly the sheep was the first mammal cloned from cells of an adult animal. She was born on July 5, 1996.
Clones do occur naturally. Some plants and single-celled organisms, such as bacteria, produce genetically identical offspring through a process called asexual reproduction. In asexual reproduction, a new individual is generated from a copy of a single cell from the parent organism.
Reproductive cloning may enable researchers to make copies of animals with potential benefits for the fields of medicine and agriculture.
Gene cloning is a carefully regulated technique that is largely accepted and used routinely in labs worldwide. However, it still raises ethical issues, as it may conflict with long-standing religious and societal values about dignity, individual freedom, identity, and autonomy.
Sources: (CNN) (National Geographic) (National Human Genome Research Institute)
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Reproductive cloning is a very inefficient technique, and most cloned animal embryos cannot develop into healthy individuals. For example, Dolly the sheep was the only clone to be born alive out of a total of 277 cloned embryos.
Another potential problem centers on the age of the cloned cell's chromosomes. As cells go through their normal rounds of division, the tips of the chromosomes, called telomeres, shrink. Over time, the telomeres become so short that the cell can no longer divide and in the end dies.
Researchers have found some health defects in cloned sheep and other mammals. These include an increase in birth size and a variety of defects in vital organs, such as the liver, brain, and heart. Other consequences include premature aging and problems with the immune system.
Critics of animal cloning typically argue that the cloning of pets could have bad consequences for the overwhelming numbers of unwanted companion animals. They also argue that animal cloning might cause health implications and pain for the cloned animal.
This is part of the natural aging process that happens in all cell types. As a consequence, clones created from a cell taken from an adult might have chromosomes that are already shorter than normal, which may give the clones a shorter life span.
Despite several highly publicized claims, there currently is no solid scientific evidence that anyone has cloned human embryos.
In 2004, a group of scientists from South Korea published a paper in a journal in which they claimed to have created a cloned human embryo in a test tube. However, an independent scientific committee later found no proof to support the claim. The scientific paper was later retracted.
Animals are cloned in one of two ways. The first is called embryo twinning. Scientists first split an embryo in half. Those two halves are then placed in a mother’s uterus, where each embryo develops into a unique animal. The two animals share the same genes.
In 1998, scientists in South Korea claimed to have successfully cloned a human embryo, but said the experiment was interrupted very early when the clone was just a group of four cells.
Another argument to create clones is in order to build populations of endangered, or even extinct, species of animals. Although some experts think cloning can save many species, others argue that cloning produces a population of genetically identical individuals that lack the genetic variability necessary for survival.
For example, the researchers who cloned Dolly also cloned another sheep that was genetically modified to produce milk that contains a human protein essential for blood clotting. The hope is that someday this protein can be purified from the milk and given to humans whose blood does not clot properly.
The second method is called somatic cell nuclear transfer. To make a clone, scientists transfer the DNA from an animal’s somatic cell into an egg cell that has had its nucleus and DNA removed. The egg develops into an embryo that contains the same genes as the cell donor. Then the embryo is implanted into an adult female’s uterus to grow.
From a technical perspective, cloning humans and other primates is more difficult than in other mammals. This is because scientists remove the nucleus from the egg and replace it with the one from the donor cell. As it can take 100 or more tries with animals, there would be even more complications with humans.
The procedure consists of inserting a gene from one organism, often referred to as foreign DNA, into the genetic material of a carrier called a vector.
Another possible use of cloned animals is for testing new drugs and treatments. The great advantage of using cloned animals is that they are all genetically identical, which means their responses to the drugs should be uniform.
Examples of vectors include bacteria, yeast cells, viruses, or plasmids. After the gene is inserted, the vector is placed in a laboratory where it will multiply.
Therapeutic cloning produces embryonic stem cells for experiments aimed at creating tissues to replace injured or diseased tissues. These cells are stimulated to divide and are grown in a Petri dish rather than in the uterus.
Over the past 50 years or so, scientists have conducted cloning experiments in a wide range of animals using a variety of techniques.
Reproductive cloning produces copies of whole animals and organisms. It transplants nuclei from body cells into eggs that have had their nucleus removed. That egg is then stimulated to divide using an electrical charge and is implanted into the uterus of a female.
There are three different modern types of artificial cloning. They are gene cloning, reproductive cloning, and therapeutic cloning.
As of 2018, around 70 countries have banned human cloning. Cloning has been seen by many as controversial, and this is mainly due to the social, ethical, and religious implications.
Cloning is a technique scientists use to create exact genetic replicas of genes, cells, or animals. The copied material, which has the same genetic makeup as the original, is referred to as a clone. And while scientists have researched and tested cloning for decades, it still sparks controversy from both animal rights activists and religious groups.
Want to learn more about cloning, and the controversy surrounding it? Then check out this gallery.
Facts about cloning and its controversy
Learn about the process of creating an identical copy of an original
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Cloning is a technique scientists use to create exact genetic replicas of genes, cells, or animals. The copied material, which has the same genetic makeup as the original, is referred to as a clone. And while scientists have researched and tested cloning for decades, it still sparks controversy from both animal rights activists and religious groups.
Want to learn more about cloning, and the controversy surrounding it? Then check out this gallery.