Word: nucleus
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Dates: during 2000-2009
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...through a process called parthenogenesis, sometimes referred to as virgin birth, since development is sparked spontaneously from the egg alone, rather than from the union of egg and sperm. Parthenogenesis is always a risk during nuclear transfer, since the process involves extensive manipulation of the egg and its nucleus. At the time that Hwang's original paper was published in Science, stem cell researchers raised the possibility that the cells had been generated by the egg alone, but the limited genetic analysis that Hwang provided appeared to rule it out. But, says Daley, "the data they presented was either wrong...
...nuclear transfer, stem cells are created by inserting the nucleus from a donor's cell, usually a skin cell, into an egg cell, whose DNA-containing nucleus has been removed. The new cell then starts to divide and produce stem cells. In some cases, however, through mistakes in the nuclear-transfer process, eggs may begin dividing on their own. And Hwang may have increased his chances of parthenogenesis by using the gentler, squeezing technique he pioneered to remove the egg's nucleus; the process may have actually left behind enough genetic material for the egg to spontaneously divide...
...years, many stem-cell researchers sought to accomplish that through nuclear transfer-transplanting an adult cell's nucleus into an egg that had been emptied of its own genetic material. This process is expensive and difficult, and so far no one has been able to pull it off in humans. Yamanaka never tried. Starting with a tiny team in 1999 at the Nara Institute of Science and Technology-he moved to Kyoto in 2004-Yamanaka focused on finding the genes that could persuade an adult cell to regress on its own to an embryonic state, without the messy mechanics...
...meantime, Eggan's group has provided an alternative method for generating customized stem cells that would take advantage of the early-stage embryos frozen in IVF centers around the country. The most reliable way of generating patient-specific stem cells remains nuclear transfer-taking the nucleus from a patient's skin cell and inserting it into an egg that has had its nucleus removed. This hybrid then begins to divide, and within a few days, generates stem cells that are genetically identical to the patient. The problem, however, as Eggan puts it, is that "there are never any extra unfertilized...
...feuding Shi'ite clans, smuggling and narcotics production. When Israel invaded Lebanon in June 1982, Toufeili was in Tehran and helped organize the deployment in Lebanon of the Iranian Revolutionary Guards who recruited and trained hundreds of young local Shi'ites to fight Israel's occupation, thus creating the nucleus of Hizballah...