Science: Lab notes

Bi-weekly news from the world of science

LONG AND FRUITFUL LIVES

Individuals who are genetically predisposed to long lives may have the added benefit of being unusually tolerant to stress, according to recent work conducted on fruit flies. Seymour Benzer and his colleagues at the California Institute of Technology looked into the involvement of particular genes in setting life span. Fruit flies with mutations in their so-called "Methuselah" gene lived 35 per cent longer than their normal kin.

Moreover, these long-lived flies also proved to be exceptionally resistant to a wide range of physical stresses, including starvation, toxins in their diet and high temperatures. In some cases, the methuselah flies survived these assaults for twice as long as normal flies. In contrast, flies with inactive Methuselah genes died while still young, even under normal conditions.

NOW THAT'S WHAT I CALL WEATHER

The latest data from the Galileo spacecraft, which has been orbiting Jupiter for over two years, offers a glimpse of terrifying, titanic electrical storms swirling around that gigantic world. Nevertheless, the forces that control Jovian weather seem to be much the same as those on Earth: low pressure systems spawn violent weather.

The lightning in Jupiter's atmosphere seems to originate within the water clouds, a layer that lies 20 to 30km beneath the ammonia clouds. In keeping with the huge scale of Jupiter, the lightning is hundreds of times brighter than the bolts on Earth. An individual Jovian lightning strike can emit as much energy as 30 million 100-watt bulbs.

The low-pressure storms on Jupiter, just like those on Earth, rotate anticlockwise in the planet's northern hemisphere and clockwise in the south. Terrestrial hurricanes are powered by warm, moist air rising up from the ocean's surface, which has been heated by the Sun. On Jupiter, which is too far away from the Sun to receive much radiant heat, the source of energy that drives storms is the warm interior of the planet itself.

The high-pressure storms on Jupiter are larger, more stable and longer- lived than the hurricane-like storms there. Three such storms, which according to the data from Galileo appear from above as white ovals in the Jovian atmosphere, have persisted in a single band around the planet's midsection for 50 years. Two of them recently combined to form a storm system as large as the Earth. That conglomerate storm has become one of the most powerful in the solar system - second only to the Great Red Spot, an even larger storm on Jupiter which has raged for 200 years.

BUBBLING TO THE SURFACE

Speaking of storms, researchers at the University of Pittsburgh and Los Alamos National Laboratory have been concentrating their efforts on the study of soap bubbles. The swirling patterns visible within these soap films are believed to offer clues to the patterns of turbulence seen within large storm systems. These scientists have now completed the first quantitative measurements of the properties of an entire soap film.

The team has obtained detailed photographs of soap films snapped at 160 to 300 microsecond intervals, measuring the rates at which vortices of soap molecules rearrange themselves within two dimensions. The energy of turbulence in these systems seemed to flow from large vortices to smaller eddies, then gradually dissipated into the background heat of the film itself.

GETTING IN ON THE ACT

Birds do it, marmosets do it, even tree shrews do it - but as every biology student knows, humans cannot grow new neurons (nerve cells) in their brains once they have matured. The tragic consequence has been that brain damage from head injuries, strokes, drug abuse or illnesses could never be undone. But now it appears that this fundamental dogma of medicine is wrong - or at the very least, far too sweeping.

Two neuroscientists, Fred Gage of the Salk Institute in San Diego and Peter Eriksson of the Goteborg University Institute of Clinical Neuroscience in Sweden, have collected the first persuasive evidence that mature - and even elderly - people do at least sometimes create additional neurons by the hundreds. This growth of neurons has so far been shown to occur in only one part of the brain - an important section called the dentate gyrus of the hippocampus, which is generally involved with learning and memory. As yet, the scientists do not know what (if anything) the newly formed neurons do, or whether the same process occurs anywhere else in the brain.

Although the discovery probably will not yield medical applications for many years, it is a major advance nonetheless. If even a few neurons can be induced to grow and carry nerve signals at critically injured points in the brain, some function might be restored to people who would otherwise be permanently damaged.

! Items adapted from `Scientific American'. Copyright 1998, Scientific American, Inc. All rights reserved