Probing Jupiter's Chilly Origins
A NASA probe that plummeted into Jupiter has produced a mystery about how and where the giant gas planet was born. "This new information might shake up our view of how the solar system formed," said Tobias Owen of the University of Hawaii, a member of the spacecraft team.
The mother ship Galileo dropped the descent probe on Dec. 7, 1995. In findings described in the Nov. 18 issue of the journal Nature, an on-board instrument measured higher-than-expected concentrations of argon, krypton and xenon in the Jovian atmosphere. The process of trapping these chemical elements (called noble gases because they don't combine with other chemicals) requires temperatures as low as minus 400 degrees Fahrenheit. But Jupiter is more than six times closer to the sun than the region where temperatures get that low.
Owen suggested three possibilities: that Jupiter was born farther out and was dragged inward; that the disk of gas and dust from which the planets formed was much colder than scientists believe; or that the solid icy materials containing the noble gases took shape before the original, vast interstellar cloud collapsed to form the sun.
If either of the latter two hypotheses proves correct, Owen said, "it would suggest that giant planets can form closer to their stars than current theories predict" and could help explain the close-in giant planets that have been discovered around other stars.
More Tolerable Pain Relief
Scientists have developed an experimental method that may be able to alleviate chronic pain without producing the side effects of drugs such as morphine.
Michael L. Nichols of the University of Minnesota in Minneapolis and colleagues created molecules in the laboratory that are designed to home in on and destroy nerve cells in the spine that transmit pain. In tests on rats, the approach appeared to work well.
The molecules consist of a toxin that has been attached to a "substance P," a natural chemical messenger that activates cells involved in transmitting pain sensations. The idea was that the molecules would selectively attach to and destroy these cells.
When the researchers injected the molecules into the spinal cords of rats, the animals became much less sensitive to pain, the researchers report in the Nov. 19 issue of Science.
The researchers hope the approach might also alleviate chronic pain in humans.
'Super Bug's' DNA Deciphered
In 1956, scientists discovered a bacterium thriving in samples of canned meat that were thought to have been sterilized by exposure to radiation. Researchers subsequently determined that the reddish organism, dubbed Deinococcus radiodurans, is the most radiation-resistant creature known to exist.
It can survive 1.5 million rads of gamma irradiation--a dose 3,000 times the amount that would kill a human.
Now, scientists report in the Nov. 19 issue of Science that they have deciphered the organism's complete genetic code, an advance they hope will lead to insights into how it manages to so efficiently repair damage caused by radiation.
The work, funded by the Energy Department and done by Owen White of the Institute for Genomic Research in Rockville and colleagues, involved determining all of the nearly 3.3 million individual chemical units that make up the bacterium's DNA.
The researchers determined that the bacterium's DNA contains an unusually high number of redundant genes that enable it to repair damage to its DNA caused by radiation, heat and other assaults.
Scientists hope to find a way to use the organism to clean up pollution and perhaps provide new insights into cancer, which can involve faulty repair of damaged DNA.
'Oxidative Stress' and Aging
Evidence has been accumulating that one of the keys to longevity may lie in the body's ability to neutralize "oxidative stress," which is damage caused to cells by the byproducts of oxygen. Now, researchers for the first time have identified a gene in mammals that appears to control how the body responds to oxidative stress.
Pier Giuseppe Pelicci of the European Institute of Oncology in Milan found that mice with a damaged gene known as p66shc lived about a third longer than mice without the defect. Otherwise, they were perfectly normal.
The researchers also determined that cells from the mutant mice were more resistant to oxidative damage from chemicals and ultraviolet light. The researchers speculated that perhaps the gene suppresses a process that repairs such damage.
"We may be at a watershed in the study of aging," wrote Leonard Guarente of the Massachusetts Institute of Technology in Cambridge, in a commentary accompanying the research in the Nov. 18 issue of Nature.
"A more robust response to oxidative damage is associated with longer life in mutants of the nematode worm, yeast and the fruit fly. [The new research is] the first to show that a simple genetic modification of this response can increase life span in a mammal. In humans, drugs given later in life might circumvent any costs on development or reproduction. We should therefore look forward to a growing research area nurtured by, if not the fountain of youth, more than a trickle of hope."