:: By Lydialyle Gibson

:: Image courtesy Heinrich Jaeger

Investigations ::

The sea squirt and the tumor
Sea squirts are poisonous to tumors, and now scientists know why. In the December Nature Chemical Biology, Chicago chemists Sergey Kozmin, PhD’98, and Alexander Statsuk, along with researchers from Stanford and the National Institutes of Health, unraveled the toxic effects of bistramide A, a metabolism by-product of sea-squirts—sessile, invertebrate marine animals—that keeps cancer cells from multiplying. According to the report, bistramide A binds itself to the actin-polymer bundles that provide the mechanical force to pinch cells apart during cytokinesis, thereby thwarting the final stage of cell division. The researchers argue that bistramide A could offer a potent biochemical tool for treating cancer.

Jet propulsion
It seems there are at least four states of matter: liquid, solid, gas, and a dense, fluid-like phase created by dropping a marble into a room-temperature container of loosely packed sand. In the December Nature Physics, University physicist Heinrich Jaeger and his team describe the phenomenon, in which the falling marble’s impact produces a jet of sand grains that briefly behaves like a dense fluid, with little random interior motion. Conducting experiments both at normal air pressure and in a vacuum, Jaeger found that air compressed between the sand grains provided the energy that propelled the jet.

Neurological semaphore
Offering the first experimental evidence for a decades-old theory about brain development, Chicago neurobiologist Yimin Zou uncovered the mechanism nerve cells use to establish connections that relay spatial information correctly from the eye to the brain. According to Zou’s results, published in the January 5 Nature, two signaling systems counterbalance to guide ”topographic mapping,” a process in which the spatial order of neurons in one part of the nervous system gets copied onto another, creating a controlled pattern of connections to transfer information.

Counterintuitive multitasking
Why do people stop for ice cream on the way home from the gym? Or splurge on luxurious vacations when they’re trying to save for retirement? Graduate School of Business professor Ayelet Fishbach says it’s because everyone pursues multiple simultaneous goals, and progress toward one frees a consumer to follow an unrelated—or even incompatible—aim. In their experiments, Fishbach and fellow researchers found that 85 percent of dieters chose chocolate bars over apples when convinced they were approaching their desired weights. Undergraduates made to believe they were relatively devoted to schoolwork, meanwhile, became increasingly interested in socializing. The results, published in the December Journal of Consumer Research, show that simply planning to work toward one goal can liberate a person to satisfy a conflicting desire.

Classroom connection
Distant, disconnected teachers may hamper ordinary high-schoolers, but they pose a downright health hazard for delinquent teens, says Dexter Voisin, a School of Social Service Administration researcher. Voisin interviewed 550 teens at eight Georgia juvenile detention centers and found that 14- to 18-year-olds reporting low “teacher connectedness” were twice as likely to use marijuana and amphetamines. They were also twice as likely to be sexually active, to have sex while intoxicated, to have a partner who was intoxicated during sex, and to have multiple sexual partners. Describing closeness with at least one caring teacher or coach as “critical,” Voisin published his findings in the October Journal of Adolescent Health.