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Clone Quirks? (video)
November 12, 2002

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Interviewees: Mike West, CEO Advanced Cell Technology; Rudolf Jaenisch, Whitehead Institute at MIT.

Video is 1 min 35 sec long. Please be patient while it loads enough to start playing.

Produced by Joyce Gramza

Copyright © ScienCentral, Inc., with additional footage courtesy of Texas A&M;, PPL Therapeutics, University Of Missouri, Advanced Cell, and Boston Museum of Science.

Also on ScienCentral News

Human Cloning - The Science (video) - Cloning could one day cure diseases like Parkinson’s, diabetes and even heart disease. But it could also be used to make a copy of a human being. (10/31/02)

Human Cloning - The Ethics (video) - The United States bars government-funded scientists from cloning human cells to cure diseases. But the nation has not outlawed cloning a human being. (10/31/02)

Elsewhere on the web

World Cloning Ban Delayed

"Attack Of The Clones: Fresh Warnings About Replication" - SpaceDaily.com

'Handmade' cloning cheap and easy - New Scientist

Reproductive Cloning Network

Clone Rights United Front

Human Cloning Foundation

Are clones normal? It's a serious question now that there's a growing industry in cloning animals, and claims that a human clone is coming soon.

This ScienCentral News story investigates why cloning experts are far from in agreement.


Jaenisch: Expression Errors

When a normally fertilized embryo develops, genes are turned on and off in a precise sequence. The genes specify the production of proteins that build each type of body cell, and build those into tissues and organs. They also code for the proteins that turn genes on and off, regulating the whole complex process. This protein-making is called gene expression.

Cloning expert Rudolf Jaenisch says the process of normal reproduction begins long before fertilization, as the egg and sperm develop into cells designed by evolution to combine and make a baby.

"Egg maturation is a process which takes decades in women for example, and sperm maturation months," says Jaenisch, a founding member of the Whitehead Institute at MIT. "But this very complex process assures that the two gametes, the mature sperm and the mature egg, that they're in a state that their genes can now activate the correct way when they come together at fertilization, to direct development of a new organism."

Cloning circumvents this process. To make a clone (see Human Cloning - The Science), you remove the nucleus from an egg cell, and replace it with a nucleus from an adult body (somatic) cell, a technique called somatic cell nuclear transfer.

"The genes in a somatic donor cell—let's say in the mammary gland cell, which gave rise to Dolly—those genes in those cells are expressed for the normal physiology of a mammary gland cell, let's say to give milk," Jaenisch explains. "But the genes which are important for embryonic development are there, but they're silent. They're not expressed."

Somehow, somatic cell nuclear transfer causes the resulting cell to be reprogrammed to act like a fertilized embryo. This reprogramming is not very well understood, but Jaenisch says one can't expect it to happen exactly as it does in normal fertilization.

"So the problem is really, you asked this somatic nucleus, let's say the one from the mammary gland, to do something in very short time, maybe hours, what normally occurs in egg and sperm maturation in months or years."

"You can't expect that this would work," says Jaenisch. "I am totally surprised that it works even sometimes and you get an adult animal."

To support this, Jaenisch cites two types of evidence:

  • Gene expression: Jaenisch's lab analyzed the genomes of cloned mice and found that many genes are not correctly expressed. The research was published in Proceedings of the National Academy of Sciences.
  • Watching clones age: He says that while these gene expression abnormalities might not be apparent in young clones, they reveal themselves as the animals age. "When we look at aged cloned animals, you only can do that in mice because cloned cows are just very young for cow ages. If you look at cloned aged mice, it turns out that all of those die earlier, significantly earlier than controls, with major abnormalities in many, many organs."

Jaenisch has become a leading advocate against cloning a human being, and his argument against it is cited by many scientists who oppose reproductive cloning of humans.

West: Don't Trash Cloning

Mike West also opposes cloning humans. But he couldn't disagree more on whether it works. "I would have to say that the cloning of human beings is probably entirely possible to do," he says.

"I've never bought the argument of some of my fellow scientists that we ought to, you know, in a sense trash cloning to try to prevent some out of control people from cloning human beings," he says [see Human Cloning— the Ethics].

West's company, Advanced Cell Technology, has cloned dozens of prized meat and dairy cattle, some now five years old and still apparently healthy.

"The realities are, we can clone animals safely and the animals are healthy for the most part," West says.

West says cloning is a useful technique that is well on its way to being practical and cost-effective.

  • Last year, Advanced Cell scientists published a paper in the journal Science that evaluated 30 cattle that were cloned from adult body cells. They said 80 percent were alive and healthy from one to four years after birth.
  • Another major cloning company, Infigen, claims that it has studied more than 120 cloned cattle and more than 50 cloned pigs, and that they are normal.

The scientists are critical of each other’s evidence. Jaenisch says Advanced Cell's criteria were superficial because they conducted physical examinations and blood tests, but did not investigate the clones at the level of gene expression. West says of Jaenisch's study, "It is true that there's abnormalities in some of the placentas, the tissue that allows the developing animal to be fed from the uterus, but not in the body of the animal itself."

"At this point," says West, "we have scientists disagreeing with one another."

Are the companies that have invested in cloning biased? West suggests that maybe they are better at cloning. West says "popular reports" that "there are hundreds and hundreds of attempts to clone with one successful result" are "largely a myth."

While not disclosing any numbers on Advanced Cell's cloning efficiency, West says it is steadily increasing. "It's not as efficient as normal reproduction, but we are steadily approaching that level of efficiency," he says.

"Should that mean we should clone humans?" West asks. "I think not, and the reason is, in the case of humans, we're far more valuable, and a mistake made, an abnormal human being, carries a far greater price than an abnormal mouse. And so until we know it's safe to clone a human being—absolutely know—I think we shouldn't even begin the experiment of trying to clone a human being.



by Joyce Gramza


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