Mosquito Noses and Baby Brains

Findings Log / by The Editors /

In this week's Findings Log, we examine new research that studies mosquitoes' sense of smell, bilingual babies, brain-computer interfaces, and more.

Findings Log is a look at some of the research and academic papers that have recently caught the eyes of Seed’s editors, Lee Billings, Greg Boustead, Veronique Greenwood, Joe Kloc, Evan Lerner, and Maywa Montenegro. For more recommended reading and occasional insights, follow them on Twitter.


Read the paperAF Carey et al. Nature February 3, 2010

Sniffing Out a Cure for Malaria
Drosophila melanogaster, the workhorse of biology labs, likes to nosh on fruit. Anopheles gambiae, aka the mosquito, prefers to dine on human blood. To find their favorite suppers, both insects rely on their antennae, which are studded with odorant receptors. By transplanting the “nose” of the mosquito into a fruit fly, researchers at Yale University have raised new possibilities for controlling the transmission of malaria. In order to engineer these souped-up flies, researchers in John Carlson’s lab first inserted mosquito genes into mutant ‘empty neuron’ fruit flies. Next they tested some 5,500 odorant-receptor combinations. Most mosquito receptors, they found, are “generalists,” reacting to a number of different odors—chemical components of human sweat, animal urine, and fruit, among others. A few receptors, however, are “specialists,” responding to a single or very small number of odors. Among these, they found 27 receptors that spiked when exposed to indole, a key ingredient of human sweat. Screening for compounds that interact with these receptors is now underway: Odors that excite the receptors could help lure mosquitoes into traps, while compounds that block their activity could mask the presence of humans. With malaria afflicting hundreds of millions of people each year, mostly in sub-Saharan Africa, such an advance will make for more than happy campers.
—MM


Read the paperC Song et al. Science February 18, 2010

The Drunken Sailor Sobers Up
Imagine the stagger of a drunken sailor: He might take a step forward; he might take a step back. He’s equally likely to take an infinite variety of sideways stumbles. Or, he may just stay put, passed out in a puddle of his own vomit. Surprisingly, such is the metaphor—known as a random walk and first purported by mathematician Karl Pearson—used to describe the possibilities of human trajectories. And models with similar theoretical underpinnings (like the Lévy-walk and Erlang theory) are employed to predict a range of complex dynamics, such as viral spreading, human crowding, and the number of calls a phone switch can handle. Although elegant, the models’ predictive power is limited, as they assume an innate level of stochasticity, or randomness. Now, a team of researchers led by network science pioneer Albert-László Barabási has shown that despite the apparent randomness of human trajectories, travel patterns may be more predictable than previously thought. Using mobile phone records to track the movement of 50,000 anonymous users over three months and calculating the entropy of these historical records, the team determined that individual travel patterns are remarkably predictable 93% of the time. It turns out that we tend to repeatedly visit a manageable number of specific places. Unexpectedly, both those who stayed close to home and those who covered hundreds of miles a day proved to be equally predictable. The results may lead to better predictive algorithms for urban planning and the study of viruses, among other complex phenomena. They also raise fundamental questions about the role of randomness in human behavior. —GB


Read the paperM Nilsson et al. PLoS ONE February 16, 2010

Saintly Skulls Betrayed by Mitochondria
Fragments of the cross on Calvary are popular relics. But if you gathered them all together, you’d wind up with far more wood than a single cross could contain. If you tested the DNA of all the saintly remains floating around, you might notice similar discrepancies. At the request of parish authorities, scientists at Uppsala University in Sweden analyzed the mitochondrial DNA of two skulls at Vadstena Abbey, purported to be those of Saint Birgitta (1303-1307) and her daughter Katarina (1331-1381). The analysis demolished any hope of a connection between the skulls: Their mitochondrial genomes, which are passed from mother to child with a high degree of fidelity, had little in common. Furthermore, the poor state of one skull’s DNA tipped scientists off that it might be much older than the other, and radiocarbon dating revealed that neither skull is from the era when Birgitta and her daughter lived—one is from the 13th century, and the other is from 15th to 17th century. Whose skulls are they? God only knows. —VG


Read the paperJF Werker et al. Psychological Science January 29, 2010

The Basis for Bilingual Babies
A study published last week in Psychological Science looked at the effect a mother’s bilingualism has on her unborn child’s language abilities. The researchers followed three groups of mothers: those who spoke English and Tagalog, those who spoke English and Chinese, and those who only spoke English. Comparing the language abilities of these mothers’ newborns, the researchers found that, just as babies with monolingual mothers are capable at birth of identifying their native language, babies with bilingual mothers are capable of identifying both of their native languages. What is most compelling about this finding is that it suggests we may not be evolutionarily wired to have only one native language. Instead, we may have an innate ability to recognize fundamental distinctions between languages like English and Tagalog. While still in the womb, we could be developing a sensitivity to the rhythm of the words being spoken around us. It makes you wonder what else we learn in there. —JK


Read the paperP Schmitt-Kopplin et al. PNAS February 16, 2010

Older Than Dirt
On Earth, aficionados of antiquity are limited by our planet’s own age—around 4.5 billion years—and an active geology that continually recycles and renews the surface. But occasionally, older things drop in, like the meteorite that fell near Murchison, Australia in 1969. Tests on the Murchison meteorite later determined it was about 4.65 billion years old—more ancient than even the Sun. Unlike most meteorites, which are composed of stone and iron, the Murchison rock was rich with carbon—the raw stuff of life. Targeted searches for amino acids and other staples of prebiotic chemistry revealed them in spades, but a more general assay of Murchison’s make-up required 21st-century technology. Now, according to a paper in PNAS, a European team using high-resolution mass spectroscopy has discovered more than 14,000 different kinds of molecules in the space rock. The meteorite probably contains millions of distinct compounds, suggesting that the early solar system hosted more chemical diversity than the modern-day Earth. During its formation in primordial clouds of dust and gas, the Murchison meteorite swept up layers of material, each uniquely shaped by the levels of temperature and radiation that prevailed at different times and places within the circulating debris. A careful extension of the European team’s techniques to study these strata could clarify how these ancient precursors congealed into a star, planets, and, eventually, people. —LB


Read the paperKJ Miller et al. PNAS February 16, 2010

Training the brain with computer interfaces
Brain-computer interfaces, or BCIs, have come a long way since the 1970s, when the term was coined. Research subjects used to spend hours meticulously practicing how to produce the specific changes in brainwaves that, when detected via sensors on test subjects’ scalps, could be translated into the binary language of computers; now, you can buy a variety of toys and games that operate on the same principles. Industrial-strength BCIs that could eventually control prosthetic limbs or other mobility-aiding devices has recently taken another leap forward, according to a paper published in last week’s PNAS. Researchers at the University of Washington recruited eight subjects and fitted the surfaces of their brains with electrodes. Tests consisted of basic physical activities—moving an arm, or saying the word “move”—followed by simply imagining those same activities. When subjects were asked to move a computer cursor by simply imagining an action, they were able to progressively improve their accuracy in hitting an on-screen target. Similar experiments on monkeys have been successful, but have never been able to test whether purely imagined activities made for useful inputs for BCIs. Moreover, the subjects’ neural activity quickly became stronger for the imagined activities than the physical ones, a good prospect for long-term use of BCI-enhanced prosthetics. —EL

Originally published February 23, 2010

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