Cloning

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Cloning

Postby Damelon » Wed Apr 09, 2003 9:48 am

I've been looking for a story like this one to come along, and knew that it wouldn't be long. What are your ideas about cloning? A good thing or not?

Here's the story:

WASHINGTON, April 8 (Reuters) -- A pair of banteng calves born last week were cloned from an animal that died more than 20 years ago, researchers said on Tuesday -- adding they hoped to rescue more endangered animals using cloning.

The two bantengs were cloned from the San Diego Zoo's "frozen zoo," a project launched before anyone knew whether cloning would work. Bantengs, found in Asia, are a species of wild cattle.

Massachusetts-based Advanced Cell Technologies said cells frozen from an animal that died in 1980 without leaving any offspring were successfully cloned using cells from cattle, and two of the babies made it to birth last week.

The experiment, a collaboration including ACT, the San Diego Zoo, Iowa State University and Trans Ova Genetics, worked in part because bantengs are closely related to domestic cattle, said Dr. Robert Lanza, chief scientist for ACT.

"The San Diego Zoo sent us a vial of frozen cells from a banteng (Stud #319) that was unique in its conservation value," Lanza said in an e-mail exchange.

"The bantengs were cloned by transferring the DNA from these cells into empty eggs from ordinary domestic cows. We implanted the cloned embryos into a herd of beef cattle which served as surrogate moms. Although we started with 16 pregnancies, only two of them went to term."

ACT did that two years ago with an oxlike animal called a gaur. The little calf died after only a few days.

The pair of bantengs looked healthy, Lanza said.

"They're both vigorous and healthy -- they look like little Bambis with their big brown eyes and ears," he said.

"We hope that the birth of these animals will open the way for a new strategy to help maintain valuable biodiversity and to respond to the challenge of large-scale extinctions ahead."

Extinct animals
Cloning truly extinct animals, such as the Tasmanian tiger, an Australian marsupial, may prove more difficult.

But cells frozen under modern conditions might offer a way to preserve animals that have more recently become endangered.

"The Zoological Society of San Diego founded a genetic bank of frozen tissues samples, known as the Frozen Zoo, more than a quarter century ago," Oliver Ryder, a geneticist for the zoo, said in a statement.

"At the time we did not know how this resource might be used, but we knew it was important to save as much information about endangered species as we could."

Experts point out that resurrecting a species will require more than re-creating an animal or two. Genetic diversity -- having many animals to interbreed -- is essential for maintaining a healthy population.

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Re: Cloning

Postby Damelon » Fri Apr 11, 2003 8:39 am

A follow-up to that story has appeared.

One of a pair of cloned bantengs, a rare species of Asian cattle, has been euthanized because it was abnormally large, its creators said on Wednesday.

The banteng calf was born twice the normal size, a common cause of death in cloned animals, said Dr. Robert Lanza of Massachusetts-based Advanced Cell Technologies.

"The second animal we euthanized yesterday," Lanza said in a telephone interview. "A banteng should only be 40 pounds (20 kg). The first calf weighed 40 pounds (20 kg) but the second was 80 pounds (36 kg), almost twice what is normal."

Despite this, the larger calf looked healthy at first. "It was snuggling and then it took a nosedive. The vets at the zoo decided for humane reasons that it should be euthanized," he said.

The two bantengs were cloned from the San Diego Zoo's "frozen zoo," a project launched before anyone knew whether cloning would work. Bantengs, enormous cattle that once thrived in the dense forests of Indonesia, Myanmar, Malaysia and elsewhere in southeast Asia, are now endangered.

The zoo, working with cloning leader ACT, hoped to resurrect a male that died in 1980 without ever breeding. They want to use his genes to breathe new life into the inbred gene pool of captive bantengs, Lanza said.

The experiment, a collaboration including ACT, the San Diego Zoo, Iowa State University and Trans Ova Genetics, worked in part because bantengs are closely related to domestic cattle, said Lanza. They cloned frozen cells from the long-dead banteng using cow eggs, and used a domestic cow as the surrogate mother.

Cloning is fraught with problems and Lanza said the calf's abnormalities did not come as a surprise.

"You don't ever know with cloned animals -- the first few days are crucial," Lanza said.

The process of cloning can lead to an abnormal placenta -- the organ that nourishes a developing embryo and fetus. Many cloned animals have been born large, and this in turn can lead to fatal heart conditions and failures of other organs.

"It not uncommon at all in cloning. It is called large calf syndrome," said Lanza.

It is also one of the reasons that most cloning experts are reluctant to ever try cloning a human being.

Wildlife groups have spoken out against the experiment, saying the best way to preserve a species is to save or resurrect its environment and allow breeding populations to re-establish.

"Until the threats that caused a species to become endangered in the first place -- poaching, habitat loss, loss of prey base -- are addressed, creating animals in the lab doesn't solve the problem," said Jan Vertefeuille, a spokeswoman for the World Wildlife Fund.

But Lanza said this was not the intention of the zoo, which wanted to preserve captive populations of bantengs. "The goal here wasn't to get a clone per se but to get the genes back into the population," he said.



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