On April 23, 1998 a sheep named Dolly was clone in Edinburgh, Scotland. No sooner had the news of Dolly hit the headlines last year there were skeptical scientists expressing doubts about this experiment. Independent DNA profiles indicate that Dolly is truly a clone. Dolly was billed as the first animal to be cloned from an adult cell. She was produced by transferring the nuclear material from a mammary cell taken from an adult ewe into an enucleated egg cell.
The donor ewe was pregnant at the time the mammary tissue was taken, so, according to some doubters, it is possible that Dolly could have been the product of a fetal cell after all. The first attempts to produce a DNA profile of Dolly suggested that she was indeed an adult clone, but the tests were not detailed enough to remove all doubt. Two reports in the journal Nature, one by Ian Wilmut of the Roslin Institute in Midlothian, UK, who originally produced Dolly, confirm that Dolly was indeed a clone of the 6-year-old donor ewe.
The other was by Esther Signer of the University of Leicester, UK, and colleagues, now providing independent DNA profiles that confirm Dolly was also a clone of the 6-year-old donor ewe. Professor Sir Alec Jeffreys, a well-known inventor of the DNA fingerprinting technique and his team at Leicester carried out the fingerprinting procedures. Mammary tissue from the original 6-year old donor ewe, cells derived from the tissue and blood samples from Dolly were all compared. The DNA fingerprints of mammary tissue, cells and Dolly were identical in band number, position and relative intensity.
Tissue and cells from the 6-year old ewe had been stored frozen at the Hannah Research Institute ever since their removal. The correspondence also includes details from Dr Colin Wilde and his colleagues at the Hannah that confirm that both tissue and cells used to make Dolly were from the mammary gland of a pregnant ewe. Work by colleagues of Dr. Wilmut indicates that the alleles present in Dolly’s DNA were identical to those in the original mammary tissue and also concludes that Dolly was derived from an adult mammary cell of a Finn Dorset ewe.
Professor Ian Wilmut of the Roslin Institute said, “Whilst we have always been certain that Dolly was derived from a mammary gland cell from an adult ewe, we are very pleased her origin has now been validated by a wholly independent and highly eminent source. ” Hope For Infertile Women A New York University fertility specialist says he has a new technique that may help an infertile woman conceive a child by adding her genetic material to a donor egg. This process is called oocyte nuclear transfer. This process requires removing the nucleus, or genetic material, from both an infertile woman’s egg and a donor egg.
The nucleus from the infertile woman’s egg is then implanted into the now-empty donor egg. In some infertile women, eggs with healthy DNA are present, but because of defects in the cytoplasm, or fluid around the egg, they cannot have a child. The reconstructed egg is then fertilized with the father’s sperm, and the resulting embryo is put into the womb of the infertile mother. If a pregnancy occurs, the fetus will technically contain genetic material from three different people. Most of the egg’s genes will come from the mother’s nucleus, and will help determine how a child looks or behaves.
However, mitochondrial genes from the donor egg will be passed to the child, too. While they do not determine physical traits, these genes can transmit inherited diseases. Lead researcher Dr. Jamie Grifo described the procedure Thursday in San Francisco at a meeting of the American Society for Reproductive Medicine. He said that the purpose of his research is to offer more options to infertile women. Grifo emphasized that his procedure is still in its experimental phase, and said he will have more to talk about when one of his patients actually gets pregnant.
The university’s scientific and ethics advisory board has given Grifo’s research team permission to complete the process on five women. Two women have undergone the procedure. The research is expected to raise some ethical questions, but Grifo says his process has nothing to do with cloning. “There are a lot of concerns about this — a lot of issues,” Grifo said. “But it’s not like we did this thoughtlessly. ” The procedure is similar to the cloning technique that produced Dolly the sheep. However, in Grifo’s technique, a child still needs genes from both a mother and a father to develop.
