Wilmut says he thinks it would be possible to clone a human—but highly unadvisable. The cloning technique used to create Dolly has been shown not to work in primates.
He believes it could be possible using other techniques but said he is vehemently opposed to the idea of cloning a person. Trounson says he believes there is a large market for cloned livestock embryos. The U. In China a company called Boyalife Group has plans to produce at least , cloned beef cattle—a fraction of the total number of animals slaughtered each year in that country, a company spokesperson wrote via e-mail. Theoretically, cloning could also be used to bring back endangered species.
Clones, however, are created by taking an adult cell and fusing it to a recipient egg cell. Making a clone requires an intact nucleus, which would not be available for most extinct species. Several researchers are now using cloning techniques to produce embryonic stem cells, thereby avoiding the need to collect new embryos. So-called somatic cell nuclear transfer may help researchers better understand early human embryogenesis and stem cell biology, according to Paul Knoepfler, a biologist at the University of California, Davis, who is not directly involved in the work.
The idea of cloning a deceased loved one—human or pet—has fallen out of favor in part because of the recognition that environment affects behavior. The genetics might be the same but would a clone still be the same lovable individual?
Lovell-Badge is even more dismissive of the idea of cloning a person. Credit: Nick Higgins. Already a subscriber? Sign in. Intellectual Property. All Policy. Patient Advocacy. Membership Options. Join Today. Member Directory. Have a Voice. Membership Eligibility. Benefits By Sector. Member Savings. VWR, Part of Avantor. Save with BIO. Popular blogs. BIO Statements. Press Releases. Amicus Briefs. BIO Reports. Industry Analysis Reports.
Biotech Jobs. Economic Development Best Practices. BIO Briefly. Issue Briefs. Good Day BIO. Health equality in access to medicines and ensuring diversity in clinical trials. In the current and next generation of black scientists and entrepreneurs. Opportunities for women, Black and other minority populations in the growing Bio-economy. Event Portfolio.
Business Development. Members Only. All Events. BIO International Convention. Learn more. October , When we got camera crews in later, they couldn't believe it, there was no room to shoot. Walker and Ritchie were part of a project at the Roslin Institute and spin-off PPL Therapeutics, aiming to make precise genetic changes to farm animals. The scientific team, led by Roslin embryologist Ian Wilmut, reasoned that the best way to make these changes would be to tweak the genome of a cell in culture and then transfer the nucleus to a new cell.
Ritchie: The simple way of describing nuclear transfer is that you take an oocyte, an unfertilized egg, and you remove the chromosomes. You then take a complete cell which contains both male and female chromosomes—all of our cells do, apart from the gonads.
You take that cell and fuse it to the enucleated egg, activate it—which starts it growing—and transfer it to a surrogate mother. Hopefully, with your fingers crossed, you will get a cloned offspring, a copy of the animal you've taken that cell from. Walker: Tedious is absolutely the word.
You're sitting, looking down a microscope and you've got both hands on the micromanipulators. It's kind of like the joysticks kids use nowadays on games. If your elbow slipped, you could wipe the whole dish out. A year earlier, the team had produced twin sheep, named Megan and Morag, by cloning cultured embryonic cells in an effort spearheaded by Roslin developmental biologist Keith Campbell.
But on this day in February , problems with the fetal cell lines they had planned to use meant that they would need another nuclear donor. Walker: My memory is of flapping like a chicken, thinking, 'What are we going to put in? The last thing you want to do is waste those oocytes you've got.
We wanted to try something, at least. Angela Scott, cell-culture technician, PPL: I received word from Karen to say that the cells they were expecting had been contaminated. They asked me if I had any cells that they could use. The cells I had were ovine mammary epithelial cells: we were looking to increase expression of proteins in milk. These were adult cells. He'd never been able to get an adult frog by using nuclear transfer from an adult cell donor.
He'd been able to get tadpoles using adult cells, but he'd never been able to get an adult frog. I didn't think it would work with adult cells at all. But we had no other cell line to go with, so we all agreed that we'd use these mammary-gland cells and just see what happened, gain some experience.
These were from a 6-year-old sheep—middle-aged for a sheep. Ian Wilmut, embryologist, Roslin: This is something that is got wrong to this day. Dolly is described as the first mammal cloned from an adult cell. She's actually the first adult clone, period.
She's often undersold. Although cloned and transgenic cows would be more valuable for industry, the Roslin team worked with sheep for practical reasons. Wilmut: Cattle are incredibly expensive and have a long generation interval. Sheep are much less expensive and much easier to work with. And we knew the reproductive biology. It was very likely that if we could make something work in sheep, it would work in cows.
Sheep are small, cheap cows. John Bracken, farm research assistant, Roslin: There would be 40—60 animals going through surgery [to retrieve oocytes or implant embryos in surrogates] each week during the breeding season. It's a lot of different sheep in the system, and that had to be very accurately monitored so the animals were at the right place at the right time.
Walker: Bill used to keep the embryos and oocytes—when he was bringing them back up from the farm—in his top shirt pocket. I didn't have a top shirt pocket, so I used to tuck them inside my bra. It was a way to keep them warm and fetch them back into the lab and get them into a proper controlled environment. I don't think inside my bra was terribly controlled, but neither was Bill's top shirt pocket.
Ritchie: On the day we made Dolly, I would have done the enucleation, and she would have done the fusion. That was our normal way of doing things. Walker: I did the fusion on the day we made Dolly. Bill and I joke, that he's the mum and I'm the dad because, essentially, I was the mimic to what the sperm would do. They transferred nuclei from the mammary cell line—from a white-faced breed known as a Finn Dorset—into eggs from the hardy Scottish blackface breed.
Just 29 of the resulting embryos were implanted into surrogate ewes. Expectations were low: it seemed almost impossible that an adult cell nucleus could be reprogrammed to give rise to a live animal.
Most cloned embryos aborted, many even before a pregnancy could be determined with ultrasound. Wilmut: The sheep breeding season begins in October and ends in February, March-ish. By Christmas, we had established pregnancies after transfer from fetal cells, so that was going well. If we hadn't done that, we probably wouldn't have gambled on working with what became Dolly, the mammary cells. Bracken: We scanned all the recipients that had embryos transferred, and we knew they were important sheep.
Every day that the scientists knew we were scanning, they would be very keen to know if there were any pregnancies. Walker: I didn't go down to watch all the scans. But with Dolly—because we knew that those were cells Bill and I had put in—I had gone down on that particular day with John. Bracken: I was just really pleased that it was a pregnancy. I didn't realize the real importance of it because we weren't really told.
We just knew it was an important pregnancy. It didn't carry the same weight. We weren't thinking, 'Wow! If this progresses to a live lamb, this is going to be a world beater, or it's going to turn scientific understanding on its head. Walker: I'd taken a blank video up with me, so that I could show my colleagues.
That video is sitting up in my loft, and to my shame, I have never yet transferred it onto DVD. I should. Schnieke: I remember the day when we had the first scan. We always asked. And then we saw the picture and the scans. Then you just have to hope that it lasts and goes all the way through.
Wilmut: My memory is they were looking around day 30 or 35, so there's another days [until the birth], where you keep on sighing with relief and hoping. Bracken: It happened about in the afternoon. As soon as she went into labour, we called the Dick Vet [the Royal School of Veterinary Studies in Edinburgh] to get one of their vets to come out. Even though [farm research assistant] Douglas McGavin and myself probably had 50 years of experience between us, it just would have been unheard of if we'd decided we'd assist the birth and something had gone wrong.
Ritchie: We knew Dolly was about to be born, and I think she was showing signs of getting near lambing, and lo and behold I went through and there were bits of Dolly being born. There was a vet there, so she made sure the animal was okay and pulled the lamb out. Bracken: It was absolutely normal. No complications whatsoever. She was a very viable lamb. She got on her feet very quickly, probably within the first half hour, which is a really good indication that things are normal. Walker: I had given her the fax number of the hotel.
I wish I had kept that fax. Wilmut: I was in the allotment. I had a phone call to say we had a live lamb. I issued an instruction that nobody should be there who didn't have to be there. Lots were curious. I obeyed my own rule because I'd got nothing to contribute.
0コメント