Cloning
It is used in a wide array of biological experiments and practical applications ranging from genetic fingerprinting to large scale protein production.
As the aforementioned procedures are of particularly low efficiency, there is a need to identify the cells that have been successfully transfected with the vector construct containing the desired insertion sequence in the required orientation.
Some vascular plants e.g. dandelion and certain viviparous grasses also form seeds asexually, termed apomixis, resulting in clonal populations of genetically identical individuals.
This is an asexual form of reproduction that is only found in females of some insects, crustaceans, nematodes,[24] fish (for example the hammerhead shark[25]), Cape honeybees,[26] and lizards including the Komodo dragon[25] and several whiptails.
Hans Spemann, a German embryologist was awarded a Nobel Prize in Physiology or Medicine in 1935 for his discovery of the effect now known as embryonic induction, exercised by various parts of the embryo, that directs the development of groups of cells into particular tissues and organs.
[32] She was cloned at the Roslin Institute in Scotland by British scientists Sir Ian Wilmut and Keith Campbell and lived there from her birth in 1996 until her death in 2003 when she was six.
[34] Dolly was publicly significant because the effort showed that genetic material from a specific adult cell, designed to express only a distinct subset of its genes, can be redesigned to grow an entirely new organism.
Before this demonstration, it had been shown by John Gurdon that nuclei from differentiated cells could give rise to an entire organism after transplantation into an enucleated egg.
Scientists speculated that Dolly's death in 2003 was related to the shortening of telomeres, DNA-protein complexes that protect the end of linear chromosomes.
Two common methods of therapeutic cloning that are being researched are somatic-cell nuclear transfer and, more recently, pluripotent stem cell induction.
Advocates support development of therapeutic cloning to generate tissues and whole organs to treat patients who otherwise cannot obtain transplants,[87] to avoid the need for immunosuppressive drugs,[86] and to stave off the effects of aging.
[95] Religious groups are divided, with some opposing the technology as usurping "God's place" and, to the extent embryos are used, destroying a human life; others support therapeutic cloning's potential life-saving benefits.
[107][108] In practical terms, the inclusion of "licensing requirements for embryo research projects and fertility clinics, restrictions on the commodification of eggs and sperm, and measures to prevent proprietary interests from monopolizing access to stem cell lines" in international cloning regulations has been proposed, albeit e.g. effective oversight mechanisms or cloning requirements have not been described.
[119][120] Engineers have proposed a "lunar ark" in 2021 – storing millions of seed, spore, sperm and egg samples from Earth's contemporary species in a network of lava tubes on the Moon as a genetic backup.
[124] These also include sending human customer DNA,[125] and a proposal for "a lunar backup record of humanity" that includes genetic information by Avi Loeb et al.[126] In 2020, the San Diego Zoo began a number of projects in partnership with the conservation organization Revive & Restore and the ViaGen Pets and Equine Company to clone individuals of genetically-impoverished endangered species.
A Przewalski's horse was cloned from preserved tissue of a stallion whose genes are absent in the surviving populations of the species, which descend from twenty individuals.
The clone, named Kurt, had been born to a domestic surrogate mother, and was partnered with a natural-born Przewalski's mare in order to socialize him with the species' natural behavior before being introduced to the Zoo's breeding herd.
[136] In a 2021 online session of the Russian Geographical Society, Russia's defense minister Sergei Shoigu mentioned using the DNA of 3,000-year-old Scythian warriors to potentially bring them back to life.
[137][138][139] The idea of cloning Neanderthals or bringing them back to life in general is controversial but some scientists have stated that it may be possible in the future and have outlined several issues or problems with such as well as broad rationales for doing so.
[140][141][142][143][144][145] In 2001, a cow named Bessie gave birth to a cloned Asian gaur, an endangered species, but the calf died after two days.
[146][147][148][149] In 2002, geneticists at the Australian Museum announced that they had replicated DNA of the thylacine (Tasmanian tiger), at the time extinct for about 65 years, using polymerase chain reaction.
[150] However, on 15 February 2005 the museum announced that it was stopping the project after tests showed the specimens' DNA had been too badly degraded by the (ethanol) preservative.
[151] In 2003, for the first time, an extinct animal, the Pyrenean ibex mentioned above was cloned, at the Centre of Food Technology and Research of Aragon, using the preserved frozen cell nucleus of the skin samples from 2001 and domestic goat egg-cells.
[157] Newsweek's 10 March 1997 issue also critiqued the ethics of human cloning, and included a graphic depicting identical babies in beakers.
[163] Science fiction films such as The Matrix and Star Wars: Episode II – Attack of the Clones have featured scenes of human foetuses being cultured on an industrial scale in mechanical tanks.
In Clark's view, the biotechnology is typically "given fantastic but visually arresting forms" while the science is either relegated to the background or fictionalised to suit a young audience.
[170][171] A Number is a 2002 play by English playwright Caryl Churchill which addresses the subject of human cloning and identity, especially nature and nurture.
[174] In a similar vein, the book The Double by Nobel Prize winner José Saramago explores the emotional experience of a man who discovers that he is a clone.
[184] In the futuristic novel Cloud Atlas and subsequent film, one of the story lines focuses on a genetically engineered fabricant clone named Sonmi~451, one of millions raised in an artificial "wombtank", destined to serve from birth.
[185] In the film Us, at some point prior to the 1980s, the US Government creates clones of every citizen of the United States with the intention of using them to control their original counterparts, akin to voodoo dolls.
