Dolly the sheep died at a young age * Dolly the sheep was a historical, scientific and revolutionary landmark in the history of cell biology and embryonic development; Her death should be a warning sign to anyone thinking of a human race
Zvi Atzmon, Galileo
On Friday, February 14, Valentine's Day, scientists at the Rosslyn Institute near Edinburgh, Scotland, announced the death of Dolly the sheep - the first mammal in history to be a clone of an adult mammal. Dolly did not die a natural death but was "put to sleep forever", meaning she was euthanized in a humane way after she was diagnosed with advanced lung disease. Rosslyn Institute scientists - led by Jan Wilmut (Wilmut), created it in the first place.
Dolly was not just any sheep, but a historical, revolutionary landmark in the history of cell biology and embryonic development. She was born on July 5, 1996, but the report on the historic birth was delayed until February 23, 1997, when it was published in the science weekly Nature ("I and the cell will admire the world", Galileo 22). Dolly had, as we wrote at the time, three mothers, and not even one father: the mother donating the nucleus and chromosomes, the mother donating the egg-without-the-nucleus, and the surrogate mother, in whose womb Dolly developed - is the mother who gave birth to her. The nuclear mother, who donated most of the DNA - the chromosomes - to Dolly, was a 6-year-old sheep, of the Finn-Forset breed. Dolly was not her daughter in the exact sense of the word, but closer to her identical twin, and she was also of the Finn-Forest race. Dolly was a cute Talia that developed into a healthy sheep. She conceived a moose named David, and gave birth to her firstborn, Bonnie, in April 1998. She later conceived and gave birth to more litters, all healthy.
Telomeres are shorter than expected - bad omens
At about four years old, Dolly looked healthy and happy. However, already in 1999 light clouds began to darken. In the test conducted by the researchers on Taya, telomeres were found to be shorter than expected for a sheep born only three years earlier. Telomeres, let's remember, are special structures located at the ends of chromosomes, structures that get shorter and shorter, "wear out" with age, when the number of divisions the cells went through to form the embryo increases. But recently researchers reported that mice with distinctly short telomeres, their fur turns gray prematurely, they often get cancer and often die at a young (chronological) age.
Did the short telomeres predict the arthritis that was discovered in Dooley about a year ago, in January 2002? Arthritis is a well-known disease in sheep, but it usually appears in sheep older than the age at which Dolly was discovered - five and a half. Furthermore - as Wilmot pointed out, the disease was unusual for Dolly's age and its characteristics were also unusual: the inflammation appeared in the joints of the back legs, a place normally not affected by arthritis. In any case, Dolly responded well to the medication and there was hope that this was just medical bad luck, and not a sign of fundamental problems with the cloning process. But lo and behold, she was recently diagnosed with an advanced lung disease and the researchers rescued her from her suffering in a humane way that is denied to us, humans. Rest in peace on a bed.
Sheep - a tiny minority among them that are not slaughtered before, can live up to the age of 11 - 12 years, and some are slaughtered until the extreme old age of 16 years. In any case, according to her date of birth, Dolly was not old when she died, but should have been in her prime. Even though she was killed due to animal cruelty, it is likely that even without this help she would have died in a short time due to her serious illness. And again - and even more so - the question of his biological age arises, in contrast to his biographical age. This question is of crucial importance when it comes to Dolly as the pioneer of the mammals cloned from an adult individual, and most acutely in relation to the cloning of adult humans. Indeed, Dolly died after being diagnosed with short telomeres, after suffering from atypical arthritis and after developing a severe and progressive lung disease, which appears occasionally in sheep, but usually in older people. Was Dolly old? What's more: Dolly died only a week after the sudden death of the first cloned sheep in Australia.
The sheep born from an udder cell
Dolly was cloned, as mentioned, from a cell that originated from an adult sheep - a cell that was actually removed from the udder, and which is the source of her nuclear DNA, her chromosomes. She received some DNA (the DNA in the mitochondria) from her "second" mother, the mother who donated the nucleus-free egg that was used to create the embryo from which Dolly developed. Since it came into the world, other mammals have been created from adult cells. However, the efficiency of the process is very low: a very small percentage of the anucleated eggs into which a mature nucleus is inserted (or they undergo fusion with a mature cell - this is the way Wilmot and his colleagues took in creating Dolly) develop into embryos that reach birth. Many cloned embryos do not develop at all, and many of those who begin to develop die while in the womb, or are born with severe defects. In those animals born as a result of cloning, defects in the heart, kidneys, liver and lungs are found in many cases, and some of them die a few days after being born.
"These facts must discourage anyone who thinks of cloning humans", says Jan Wilmot, who consistently expresses a strong opposition to human cloning. At this point it seems that any practical plan for human cloning seems irresponsible in a cautious language, and in a less official language: shocking. And this must be remembered: in order to obtain approval for the use of a new substance as a medicine, even if it is a medicine for terminally ill people, whose condition is almost hopeless, one must go through a long and exhausting process, during which the developers are required to prove that the medicine is safe to use and beneficial to the patients. And here, this is a process whose effectiveness - at least at this stage - is extremely low, and whose results in many cases are very difficult. Dolly's illnesses and her death exacerbate, as mentioned, the fears: even if the fetus develops normally and is born healthy, there is still, and now is even stronger, the fear that its life expectancy is short, and that at a young biographical age, signs of old age and degeneration will be discovered in it. No wonder scientists around the world are eagerly awaiting the results of a careful examination of Dolly's body.
Dolly - now grazing and grazing in the eternal heavenly pastures - will in the near future become a monument of her own: after a careful examination, her body will be embalmed, and she will be put on display at the Scottish National Museum in Edinburgh. Hello Dolly.
