American Scientist

This roundup of notable recent items about scientific research, culled from news reports, was compiled from free electronic newsletters produced by Sigma Xi's Public Understanding of Science program.

Astronomers Observe Explosion from Early Universe

NASA's Swift satellite orbits the Earth trying to detect gamma-ray bursts—massive explosions of radiation released when giant stars died brilliantly long ago and collapsed into black holes. The flashes of light last only seconds and never get inside the Earth's atmosphere. The astronomers behind Swift were rewarded in September when the satellite detected energy from one of the blasts, pivoted quickly to determine its whereabouts and alerted astronomers, including Daniel Reichart of the University of North Carolina at Chapel Hill. Reichart rushed to a facility  from which he could control a telescope perched in the Andes Mountains. He and undergraduate student Josh Haislip got the data they needed on the afterglow of the burst, then determined that the explosion was older and farther away than any explosion ever observed. It occurred 13 billion years ago, only 700 million years after the Big Bang.

See NASA press release at http://www.nasa.gov/vision/universe/starsgalaxies/sburst05_pressrelease.html; preprint at http://arxiv.org/abs/astro-ph/0509660.

Biologists Unveil Key to Genetic Variations Behind Disease

Geneticists have completed a map of human genetic variation, a sliver of the human genome—one-tenth of one percent. Genes that contribute to diseases such as cancer, diabetes and hypertension lurk among those variations, and the new map provides an important tool for ferreting out the genetic markers of those diseases. Before the map's publication, biologists had to scour all 3 billion individual nucleotides to spot individual variations, called single nucleotide polymorphisms or SNPs. The new map capitalizes on the revelation that SNPs can be spotted by looking for variation at the level of haplotypes, larger strings of DNA that are inherited together. That reduces to 1 million the number of places to search for those variations that mark susceptibility to disease.

The International HapMap Consortium, A Haplotype Map of the Human Genome, Nature 437:1299-1320 (October 27, 2005).

Mice-tro Kings Squeak Songs of Love

We're not the only musical species—birds, whales, dolphins and gibbons are all known to sing, though the reasons aren't always clear. Now we can add mice, thanks to an accidental discovery in a Washington University lab. Neurobiologists were investigating what goes on in rodents' brains when they sense sex pheromones. Recording male mice as they sniffed cotton swabs treated with the urine of females, they picked up a distinctive pitch, songs too shrill to be heard by the human ear. A pitch-shifted playback revealed their musical nature. The discovery could advance research into the origins and causes of speech.

Holy, T. E., and Z. Guo. Ultrasonic songs of male mice. Public Library of Science Biology 3(12):e386 (November 1, 2005).

Not Heavy Haulers, but Nanotrucks Are Neat!

Rice University engineers have built a fleet of tiny molecular vehicles that could ferry nano-payloads. The nanocars and nanotrucks are so small that 20,000 of them could line up across the width of a human hair. They roll along on tiny pure-carbon buckyballs and feature a suspension system allowing the vehicles to surmount atomic obstructions. Objects built to the nanoscale—a nanometer is a billionth of a meter—have some special properties. For instance, the buckyball wheels are virtually indestructible because each is a single molecule not likely to break up into its 60 atoms of carbon.

Shirai, Y., et al. Directional Control in Thermally Driven Single-Molecule Nanocars. Nano Letters 5 (11): 2330-2334 (November 9, 2005).