American Scientist

This roundup summarizes some notable recent items about scientific research, selected from news reports compiled in Sigma Xi's free electronic newsletters.

Taking Air Pollution to Heart

In the past few years, medical researchers have linked air pollution with heart disease. In particular, high levels of particulate matter in the air constitute a risk factor for the disease, along with the usual suspects: smoking, high blood pressure, aging, physical inactivity, poor diet, and high levels of so-called bad cholesterol. A new study shows that exposure to ultrafine particles promotes atherosclerosis in mice. The research also suggests the biological mechanism that may be at work. The tiny particles, together with certain oxidized lipids in the blood, turn on genes involved in vascular inflammation.

Gong, K. W., et al. Air-pollutant chemicals and oxidized lipids exhibit genome-wide synergistic effects on endothelial cells. Genome Biology 8:R149 (July 26)

A Southpaw Gene

Biomedical researchers have discovered a genetic signature linked to handedness. When someone inherits this particular pattern from his or her father, it seems to predispose the person to be left handed, whereas receiving the same genetic pattern from one's mother has no such effect. This curious genetic pattern lies close to a gene called LRRTM1 (shorthand for leucine-rich repeat transmembrane neuronal 1), which, the investigators showed, is largely switched off when it is maternally inherited. The study also suggests that the genetic pattern linked with left-handedness may influence one's susceptibility to developing schizophrenia—but, again, only if it is inherited paternally.

Francks, C., et al. LRRTM1 on chromosome 2p12 is a maternally suppressed gene that is associated paternally with handedness and schizophrenia. Molecular Psychiatry (published online July 31)

How Now, Brown Cloud?

The glaciers of the Himalayan and Hindu Kush regions of Asia have been shrinking at increasing rates over the past several decades. Although it is tempting to blame burgeoning levels of carbon dioxide, new research carried out over the Indian Ocean using unmanned aerial vehicles suggests that atmospheric brown clouds are equally capable of heating the atmosphere at these high elevations. Such clouds result from biomass burning and the combustion of fossil fuels.

Ramanathan, V., et al. Warming trends in Asia amplified by brown cloud solar absorption. Nature 448:575–578 (August 2)

Three Syllables, Sounds Like . . .

Psychologists studying the way captive orangutans communicate with humans report an interesting finding. When the animals believe they are at least partially understood, they repeat whatever gesture they think worked. But if they fail in an attempt to communicate their desires (in particular, their wish to be given an especially tasty kind of food), they quickly abandon whatever strategy they were using and try another one. This behavior thus communicates to the observer, be it a human experimenter or another orangutan, whether the gesturer has been understood—a phenomenon familiar to anyone who has ever played the parlor game charades.

Cartmill, E. A., and R. W. Byrne. Orangutans modify their gestural signaling according to their audience's comprehension. Current Biology 17:1345–1348 (August 7)

Gene Popsicles

Biologists have uncovered evidence of bacteria surviving perhaps as long as eight million years in ice. The investigators examined samples taken from the Dry Valleys of the Transantarctic Mountains, where some very ancient ice remains. Their analyses of thawed ice revealed a soup of bacterial DNA, and experiments demonstrated some metabolic activity. Most probably, the ancient organisms were revived from an inactive frozen state, although it is also possible that these hardy bacteria remained alive and well the whole time, surviving in tiny fluid inclusions within the ice.

Bidle, K. D, S. Lee, D. R. Marchant and P. G. Falkowski. Fossil genes and microbes in the oldest ice on Earth. Proceedings of the National Academy of Sciences of the U.S.A. 104:13455–13460 (August 14)

Save Your Energy

Batteries are a familiar way to store energy for use in portable electronics, but they are not the only means available. When the demand for power is high but the overall energy-storage requirements are modest, capacitors can also be used—ones especially designed for this purpose. These "supercapacitors" or "ultracapacitors," as they are called, normally contain electrodes made of activated carbon, which are immersed in an electrolyte solution and separated by a porous insulator. Engineers have now integrated all these elements into a flexible paper-like energy-storage device that uses carbon nanotubes for the electrodes. Their invention can serve as a capacitor, a battery or as a capacitor-battery hybrid.

Pushparaj, V. L., et al. Flexible energy storage devices based on nanocomposite paper. Proceedings of the National Academy of Sciences of the U.S.A. (published online August 15)

Not So Alike After All

Although two separate analyses of the complete human genetic sequence were published in 2001, neither of those investigations mapped the entire diploid genome—which includes chromosomes inherited from both mother and father. But a newly released genetic study has now managed that feat. Unlike the earlier work, which analyzed DNA from various subjects, the new work used material from just one person: J. Craig Venter, the biotechnology entrepreneur who, not coincidentally, spearheaded this project. This study suggests that the variation in genetic sequence between different people, formerly thought to amount to only 0.1 percent, is likely five times higher.

Levy, S. et al. The diploid genome sequence of an individual human. Public Library of Science Biology 5(10): e254 (October)