American Scientist

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

Olfactory Orienteering

In the monotonous Sahara landscape, desert ants (Cataglyphis fortis) will use any landmarks they can get—including scents. When foraging, the ants use the Sun and a sense of distance to find their way, but researchers wondered if odors could be landmarks too. They arranged four aromas asymmetrically around a nest entrance, let the ants get used them, then moved 30 ants to a location with the same scents but no nest. The insects searched exactly where the nest hole should have been, as long as they had both antennae intact. If the researchers rearranged the scents, the ants got confused and searched more broadly. The result adds insight into the ants’ formidable positioning system—and makes them the first organisms known to navigate using a stereo sense of smell.

Steck, K., et al. Do desert ants smell the scenery in stereo? Animal Behaviour (published online February 21)

Spying on Proteins

For the first time, researchers have peered into a living cell and watched its proteins fold and unfold in real time. The method uses fluorescent tags at both ends of a given protein: When the protein is folded, the tags are adjacent and influence one another. But when it denatures, they move apart and one of them ceases to glow. By monitoring fluorescence, the researchers could tell how fast the protein changed shape in response to temperature change. They found that it did so more slowly in the crowded environment of a live cell than it did in vitro—where protein dynamics are usually studied. The new technique could eventually provide insights into many physiological processes, including abnormal protein behavior in disorders such as Alzheimer’s disease.

Ebbinghaus, S., et al. Protein folding stability and dynamics imaged in a living cell. Nature Methods (published online February 28)

Smoggy Spring Breeze

Ozone levels are rising over California, and it’s not L.A.’s fault: New research traces a share of the pollution to Asia. The study incorporated about 100,000 springtime ozone measurements over western North America, mostly between two and five miles above the ground. To estimate the geographic origin of each air sample, researchers used wind records and computer models. They found that between 1995 and 2008, ozone concentrations rose 14 percent—the first conclusive evidence that ozone is increasing in the region. Further, the pollutant upsurge was most striking in the air that had blown over directly from Asia. The study didn’t look at imported ozone throughout the rest of the year—but the springtime data alone indicate that international cooperation will be essential to maintaining air quality.

Cooper, O. R., et al. Increasing springtime ozone mixing ratios in the free troposphere over western North America. Nature 463:344–348 (January 21)

Faithful Frog Couples

Biologists in Peru have made a rare find: monogamy in a frog. Indeed, the poison dart frog Ranitomeya imitator is the first monogamous amphibian known to science. Genetic tests of the frogs and their offspring confirmed monogamy in 11 mated pairs, and researchers think they know what keeps the frogs faithful: They raise their tadpoles in tiny pools of water. Cupped in plant leaves, these pools hold little more than a tablespoon of water and not enough food for a growing tadpole. Although most dart frog moms would mate again, leaving the father to guard the tadpoles, R. imitator’s mini-puddles call for extra measures. The mother sticks around and, at the father’s call, lays unfertilized eggs to feed the tadpoles. Such close cooperation leaves little room for dallying.

Brown, J. L., et al. A key ecological trait drove the evolution of biparental care and monogamy in an amphibian. The American Naturalist 175:436–446 (April)

Exploring Jupiter’s Red Eye

Astronomers have come up with the first detailed weather map of Jupiter’s Great Red Spot—a feature noted by stargazers since the 1600s. The spot spans more than three Earth-diameters and is the solar system’s oldest and largest storm. Now, thanks to detailed infrared images from Earth-based telescopes such as the Very Large Telescope in Chile, astronomers are piecing together circulation patterns within this Jovian tempest. The new images reveal, for example, that the deep red center is three to four degrees Celsius warmer than the rest of the storm, causing it to rotate clockwise while the rest of the spot circulates counter-clockwise. The results are the first to link temperature and wind conditions to the visible color of the spot. The chemistry that produces that ruddy hue, however, remains a mystery.

Fletcher, L. N., et al. Thermal structure and composition of Jupiter’s Great Red Spot from high-resolution thermal imaging. Icarus (published online February 6)

Chivalry Takes Time

As the Titanic sank slowly to its doom in 1912, men sacrificed themselves to help women and children—so much so that women had a 53 percent greater chance of survival than men, and children a 15 percent greater chance than adults. Economists say that’s because passengers had nearly three hours to stifle panic and heed social norms. Not so on the Lusitania, a ship that went under in just 18 minutes. The two vessels were otherwise similar: They sank three years apart and had comparable passenger demographics and overall survival rates. But the men on the Lusitania took care of themselves and outlived other passengers. It could be that survival instincts during the ship’s brief demise were so overpowering that physical ability and chance, not chivalry, determined who stayed afloat.

Frey, B. S., et al. Interaction of natural survival instincts and internalized social norms exploring the Titanic and Lusitania disasters. Proceedings of the National Academy of Sciences (published online March 1)