Frozen Mice Cloned – are woolly mammoths next?
Japanese scientists have cloned mice whose bodies were frozen for as long 16 years and said on Monday it may be possible to use the technique to resurrect mammoths and other extinct species.
Mouse cloning expert Teruhiko Wakayama and colleagues at the Center for Developmental Biology, at Japan’s RIKEN research institute in Yokohama, managed to clone the mice even though their cells had burst.
“Thus, nuclear transfer techniques could be used to ‘resurrect’ animals or maintain valuable genomic stocks from tissues frozen for prolonged periods without any cryopreservation,” they wrote in the Proceedings of the National Academy of Sciences.
Wakayama’s team used the classic nuclear transfer technique to make their mouse clones. This involves taking the nucleus out of an egg cell and replacing it with the nucleus of an ordinary cell from the animal to be cloned.
When done with the right chemical or electric trigger, this starts the egg dividing as if it had been fertilized by a sperm.
“Cloning animals by nuclear transfer provides an opportunity to preserve endangered mammalian species,” they wrote.
“However, it has been suggested that the ‘resurrection’ of frozen extinct species (such as the woolly mammoth) is impracticable, as no live cells are available, and the genomic material that remains is inevitably degraded,” they said.
DIGGING INTO FREEZERS
Wakayama’s team dug out some mice that had been kept frozen for years and whose cells were indisputably damaged. Freezing causes cells to burst and can damage the DNA inside. Chemicals called cryoprotectants can prevent this but they must be used before the cells are frozen.
They tried using cells from several places and discovered that the brains worked best. This is a bit of a mystery, as no one has yet cloned any living mouse from a brain cell.
Many animals have been cloned, starting with sheep, and including pigs, cattle, mice and dogs. Livestock breeders want to use cloning to start elite herds of desirable animals, and doctors want to use cloning technology in human medicine.
“There is hope in bringing Ted Williams back, after all,” cloning and stem cell expert John Gearhart of the University of Pennsylvania said in an e-mail. The family of Williams, the Boston Red Sox hitter, had his body frozen by cryogenics firm Alcor after he died in 2002.
Gearhart was only half-joking and said the study “may now stimulate the small industry of freezing parts of us before we die to bring us back in the future.”
Mammoths may be the extinct animals that scientists would be most likely to try to clone, as many of the animals have been found preserved in ice.
In July 2007 Russian scientists discovered the body of a baby mammoth frozen in the Arctic Yamalo-Nenetsk region for as long as 40,000 years.
“It remains to be shown whether nuclei can be collected from whole bodies frozen without cryoprotectants and whether they will be viable for use in generating offspring following nuclear transfer,” Wakayama’s team wrote.
AT&T to try limits on monthly Internet traffic
AT&T Inc. (ATT), the country’s largest Internet service provider, is testing the idea of limiting the amount of data that subscribers can use each month.
AT&T will initially apply the limits in Reno, Nev., and see about extending the practice elsewhere.
Increasingly, Internet providers across the country are placing such limits on the amount of data users can upload and download each month, as a way to curb a small number of “bandwidth hogs” who use a lot of the network capacity. For instance, 5 percent of AT&T’s subscribers take up 50 percent of the capacity, spokesman Michael Coe said Tuesday.
But the restrictions that Internet providers are setting are tentative. And the companies differ on what limits to set and whether to charge users for going beyond the caps.
Starting in November, AT&T will limit downloads to 20 gigabytes per month for users of their slowest DSL service, at 768 kilobits per second. The limit increases with the speed of the plan, up to 150 gigabytes per month at the 10 megabits-per-second level.
To exceed the limits, subscribers would need to download constantly at maximum speeds for more than 42 hours, depending on the tier. In practice, use of e-mail and the Web wouldn’t take a subscriber anywhere near the limit, but streaming video services like the one Netflix Inc. (NFLX) offers could. For example, subscribers who get downloads of 3 megabits per second have a monthly cap of 60 gigabytes, which allows for the download of about 30 DVD-quality movies.
The limits will initially apply to new customers in the Reno area, AT&T said. Current users will be enrolled if they exceed 150 gigabytes in a month, regardless of their connection speed.
“This is a preliminary step to find the right model to address this trend,” Coe said. The company may add another market to the test before the end of the year, he said.
Customers will be able to track their usage on an AT&T Web site. The company will also contact people who reach 80 percent of their limit. After a grace period to get subscribers acquainted with the system, those who exceed their allotment will pay $1 per gigabyte, Coe said.
Comcast Corp. (CMCSA) (CMCSA), the nation’s second-largest Internet service provider and AT&T’s competitor in Reno, last month officially began a nationwide traffic limit of 250 gigabytes per subscriber. Comcast doesn’t charge people extra for going over the limit, but will cancel service after repeated warnings. Previously, it had a secret limit.
Two other ISPs, Time Warner Cable Inc. (TWC) (TWC) and FairPoint Communications Inc. (FRP) (FRP), are planning or testing traffic limits as low as 5 gigabytes per month, which is easily exceeded by watchers of DVD-quality online video.
Among the largest ISPs, Verizon Communications Inc. (VZ) is a holdout, and has said it does not plan to limit downloads.