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Science & Technology
 In the news of science

Scientists in the United States have created a genetically modified mouse that changes colour

From Diana J. Choyce
July 02 - 08, 2001

If you plan on being around in about 5 billion years, you might be in for a catastrophic event involving the sun. It is estimated that the dying sun will then expand and remove all life from Earth. But a group of astrophysicists say, if we just widen our planet's orbit, bit by bit, over time we can avoid disaster. "We started thinking that if you could move the Earth, you could buy some time," says Don Korycansky, lead author of a recent paper in Astrophysics and Space Science and a researcher at the University of California at Santa Cruz. He and two other scientists propose gradually shifting Earth's orbit to keep pace with the expansion of the sun. The scientists say the change in orbit must be incremental to match the slow transformation of the sun into a red giant, an expanding, but dying, star. "You don't want to move the Earth all at once because it would be too cold," Korycansky says. The theory calls for carefully rocketing an asteroid or other object past Earth within 10,000 miles. The close pass of the asteroid would pull our planet slightly away from the sun, about 30 miles from its original orbit, the scientists estimate. "They would sort of tug at each other," says Korycansky. Known as "gravity-assist," the technique is already used by space programmes to propel space probes through the universe by swinging them past other planets. Whew, and I thought we were doomed!

Scientists in the United States have created a genetically modified mouse that changes colour. The pure white rodent grows a brown coat when a special supplement is added to its diet. When the sugary substance is withdrawn, the mouse reverts to its white coat. Researchers say the work could lead to a better understanding of human genetic diseases and cancer. The study is bound to prove controversial among groups opposed to animal research. Dr Heidi Scrable of the University of Virginia, Charlottesville, said: "It demonstrates that we can turn genes on and off in the mouse, which is the principal experimental animal that we have for modelling human diseases." She said the mouse would be an important tool for medical research since some genes are virtually identical in the mouse and the human. One particular challenge is cancer. The team plans to study a gene implicated in many cancers in a bid to find out how common tumours develop. "Many people consider pathogenesis a form of development gone awry," Dr Scrable told BBC News Online. "By studying the function of particular genes during development we can begin to understand how an alteration in that function might lead to human disease."

UK consumers may get the chance to buy a small kitchen appliance which can inject carbon dioxide into fresh fruit, turning it into "fizzy fruit" which tickles the taste-buds as it is eaten. The invention is the brainchild of University of Texas neurobiologist Dr Galen Kaufman who is developing a kitchen worktop fruit carbonating machine in conjunction with the Food Innovation Centre at the University of Oregon, USA. "The first step will be making a machine that will make fruit fizzy in the home. Supermarket distribution is still some way off," he says. "The Centre for Food Innovation is working on the exact engineering parameters and that research will take several months yet. The discovery that carbon dioxide would dissolve almost as easily in fruit as in water led to his invention of the "fizzy box", a Plexiglass chamber pumped full of pressurized gas. So far Dr Kaufman has carbonated apples, pears, strawberries, peaches, nectarines and watermelons. He says that any fruit which is 80% water can be carbonated. He believes there are longer term prospects for distribution of tinned or frozen "fizzy fruit". No other form of packaging would be able to contain the gas. The technique will probably never be applied to bananas. They immediately explode if injected with gas.

A spinach packed with HIV-suppressing proteins may be the first step in the use of plants as a cheap, safe method of delivering AIDS vaccines to those who need them. "The ideal situation would be a prescription for a bowl of spinach'' that would either help prevent or treat HIV infection, said lead study author Dr. Alexander Karasev of Thomas Jefferson University in Philadelphia, Pennsylvania. He presented his team's findings at the annual meeting of the American Society for Microbiology. But why use plants to produce and deliver such a vaccine? ''The essential point is that vaccines are a very expensive business, so anything that can drive the cost down will be beneficial,'' Karasev told Reuters Health. Vaccines that grow naturally in plants would be much cheaper to harvest than those produced in the lab, he said. "On the other hand there's a second issue, which is probably even more important—safety. Whatever is produced in terms of vaccine components in animal cultures, or sometimes even in human tissue cultures, carries the remote possibility of contamination,'' he said. Plant-based vaccines would greatly reduce this risk, he noted. But the virus that causes AIDS remains a complex adversary. ''With HIV, unfortunately we don't have a magic bullet right now,'' Karasev said. "Nobody knows which particular gene will be the best candidate for vaccination.'' Perhaps, he said, more than one HIV-expressed protein will be needed to allow the immune system to effectively fight HIV. "If we can extract several different proteins of HIV from the same plant, it may help to create a combined vaccine.'' And although the prospect of patients eating their way to immunity may be attractive, variance in eating patterns may make that method impractical, given the specific drug dosages needed to fight AIDS, or any disease. "We're trying to test whether these spinach plants can be dried, stored and formulated in special tablets or something like that,'' Karasev stated.