Cloning Part 2

Cloning of Animals from Adult Cells The nucleus of a body cell (somatic cell) is removed from the animal you want to clone. This contains the genes for that animal. An egg cell is taken from another animal, and its nucleus is removed. The nucleus from the animal you want to clone is put into the egg. The process is called somatic cell nuclear transfer.

Cloning of Animals from Adult Cells The method involves resetting the “program” of the adult nucleus to make its genes act like those of a fertilized egg. The egg is stimulated to divide, and it begins to make an embryo. The embryo is put into a foster mother animal and allowed to grow.

Two major goals of cloning Reproductive cloning – to create genetically identical animals Therapeutic cloning – to grow stem cells that can then be used to treat disease

Possible side effects of cloning genetic defects – found to be more common in cloned animals other health problems, such as premature aging as yet no evidence that cloned animals die younger

Cloning and Genetic Engineering We have previously discussed how genetic engineering can be used to make medically useful animals: “pharming” in drug production animals with human-like organs for transplantation When an engineered animal like this is created, cloning is used to make many identical animals.

Reproductive Cloning of Horses First horse cloned in 2003. 20 have been cloned in last 3 years. Not permitted in thoroughbred racing. Allowed for show jumpers and rodeo horses. “Cloned foals are likelier to be weak or have crooked legs.” Source: Philadelphia Inquirer, Jan. 20, 2009

Reproductive Cloning of Dogs “Cloning dogs is considered difficult because of their complicated reproductive physiology…” “…but the procedure has been perfected in South Korea.” Not clear if this will be a successful business. An American couple paid $155,000 in an auction to have their dog cloned. With so many dogs unable to find homes, is it ethical to clone more? Source: CNN, Feb. 6, 2009

Reproductive Cloning of Dogs

Cloning of Endangered Species For endangered species, cloning may be a way to help increase the numbers of animals Instead of waiting for the slow process of reproduction in zoos or in nature, eggs can be raised in surrogate mothers using a related animal.

Cloning of Endangered Species In 2001 an ox-like animal, the gaur, was cloned in a cow (but the baby gaur died soon after birth due to infection)

Cloning of Endangered Species Drawbacks: Will still have the problem of limited genetic diversity, and will be sensitive to disease or change in conditions. Will not solve the problem that made them endangered (such as loss of habitat) Would it be better to spend money on protecting these species?

Cloning of Extinct Species Efforts have included: Mammoth – team from Russia and Japan. Thylacine (Tasmanian Tiger) – Australian National Museum. Both projects have had problems with the DNA being too degraded.

Cloning of Dinosaurs? Very unlikely: No one has yet isolated any dinosaur DNA. If they do find it, it would mostly be degraded after tens of millions of years. You would need enough to cover the whole genome.

Cloning of Dinosaurs? Very unlikely: Even if you had the DNA, you would need to put the genes in an egg. The genes would not function properly without the right environment. A bird would be the closest relative, but would probably be too different for the dinosaur genes to work.

Cloning of Humans Possible reasons: Fertility problems – could clone one parent. Replace a child that died. Vanity Source of replacement organs or tissues Attempt to replicate a famous or valuable individual

Cloning of Humans At present, the low success rate seen with other animals, and chance for defects, make this difficult and unethical. However, it would not be surprising to see successful human cloning take place somewhere in the world in the next few years.