history of cloning
Cloning may seem to by unrealistic and not yet performed in our world. However, it has been around for quite a while. There are many instances where animals have been cloned, which makes cloning for endangered and extinct species definitely possible and would allow for us to save them. With the development of cloning up until today, the possibility of cloning extinct species seems likely.
1952 - Nuclear transfer from an undifferentiated cell
Cloning from early embryonic cells worked, however, it was less successful with older embryos. Robert Briggs and Thomas King removed a nucleus from a frog egg and inserted the nucleus of an early tadpole embryo. It was revealed that cloning was more successful with embryonic cells.
This experiment allowed other scientists to understand that the nucleus is in charge of directing of growth and development of the cell.
1958 - nuclear transfer from a differentiated cell
A differentiated cell is a cell that has been specialized to do its job in the body.
John Gurdon created genetically identical cells to its owner by transferring the nucleus of a tadpole intestine cell to an enucleated egg.
This led to the conclusion that cells are able to develop from differentiated cells can be used to clone. It reveals that using a differentiated cell from an endangered or extinct species can possibly result in a great success to restore their life.
1997 - nuclear transfer from genetically modified laboratory cells
Angelika Schnieke, Keith Campbell, and Ian Wilmut used a previously created clone with using the nucleus of a cultured cell. The researched inserted a gene, called the human Factor IX gene into the sheep's skin cells' genome, which codes for a protein that helps with reducing blood clots and treating hemophilia.
The scientists used donor DNA from a transgenic cell. The result was a sheep that produced the gene Factor IX in her milk.
This experiment demonstrates the ability to alter a gene so that there are potential medical and supplemental uses.
2001 - endangered animals cloned by differentiated cells
As the idea of cloning grew, many groups of scientists wanted to find a way to clone endangered or extinct animals. However, one trouble was finding an animal closely related enough to act as a surrogate mother.
2009 - first extinct animal cloned
The last bucardo, a Spanish mountain goat, died in 2000. However, a group of researchers were able to clone the extinct animal by using the frozen skin cells by one of the bucardos in 1999. Folch and his group inserted the bucardo's DNA into a goat, a subspecies of the extinct animal. However, it was only able to live for a few minutes due to a lung defect.
With improved technology and newer sciences within time, it can be possible to successfully clone extinct animals that would be able to reproduce naturally and begin their species again.
1984 - first cloned mammal
Using a chemical process, Steen Willadsen used a cell to separate from a lamb embryo and fused the cell to an enucleated egg cell by using a small electric shock.
Willadsen placed the embryo into a surrogate mother sheep and resulted in three lambs.
The experiment showed that it was possible to clone a mammal from an early embryonic cell. The possibility of cloning from a differentiated cell was still deemed as unlikely.T.1
1996 - dolly the sheep
Dolly the Sheep was classified as the first mammal to be cloned from an adult somatic cell. Ian Wilmut and Keith Campbell enucleated an egg and transferred the nucleus from the sheep's udder into the enucleated egg.
But, what makes the cloning of Dolly so important? It was the first cloned mammal to succeed from having the DNA from a differentiated cell. Differentiated cells are harder to clone because they turn off certain genes that they do not need for their role. Undifferentiated cells, or embryonic cells can activate any gene because it is not specialized in a certain role.
Dolly was the first successful lamb out of 277 attempts. Dolly was able to reproduce naturally, which supports that cloned animals can provide offspring to continue their species.
1997 - First cloned primate from an embryonic nuclear cell transfer
Similar to other cloning processes, Don Wolf's team of scientists enucleated a monkey egg shell, fused an early-stage embryonic nucleus with an electric shock and inserted it into a surrogate mother. Two monkeys were born out of 29 attempts of cloned embryos.
This experiment proved that humans' closest relative, primates, can be cloned.
