Friday, November 21, 2008

Discover Magazine's Top 20 Under 40 - Panspermia/RNA World Theory, and Genoanthropology, Plus - Choanoflagellates

Choanocytes, the feeding cells of sponges,
are part of Nicole King's study of early evolution.

Nicole King
Molecular and Cell Biologist, University of California at Berkeley

Nicole King, 38, is hunting for an answer to how the evolutionary leap occurred from single-celled organisms to plants, fungi, multicelled animals, and other forms of life. To find clues, she has trained her sights on choanoflagellates—a group of single-celled eukaryotes thought to be the closest living relatives of animals.

Sequencing the genome of one such organism, King and her colleagues found genes that code for pieces of the same proteins used for the binding of cells and communication between cells in animals —functions that would be unexpected in such an organism. King hypothesizes that proteins that the single-celled ancestors of animals used to interact with the extracellular environment—to capture bacterial prey by binding to their cell surface and to detect chemical signals—were later repurposed to enable cells to stick to and talk to each other. Interpreting the origins of multicellularity is key to understanding the origins of animals, King says, noting that her research “reaches back much further on the family tree than our common ancestors with other primates.” —Y. B.

Edward Boyden
Neuroengineer, MIT Media Lab

Certain species of bacteria and algae have genes that allow them to transform light into electrical energy. Edward Boyden, 29, has been able to show that inserting one of these genes into a neuron can make it similarly responsive. “When we illuminate these cells...we can cause them to be activated,” he says.

Having created such genetically modified neurons, Boyden is engineering brain implants that can stimulate them with light pulses. Boyden’s implants, he hopes, will be used to help control diseases like Parkinson’s, which is sometimes treated with implanted stimulators that issue electric current. “There are things that light can do that purely electric stimulators can’t,” Boyden says. With this technology, researchers can be selective about which neurons they engineer to be responsive, and an optical implant can emit light in a variety of patterns, allowing more precise control over neural circuits. —E. A.

Richard Bonneau
Systems Biologist, New York University

Chronicling the parts of cell anatomy class-style is all well and good, says Richard Bonneau, 33, but biologists’ true holy grail is understanding how each part dictates the function of the others. “You might know that A is related to B, but if you don’t have a dynamic picture of your system, you don’t know which part is affecting which,” he says. “I want to put the arrows on the lines, so to speak.”

By tracking activity in almost all the genes of a free-living archaeon—which, like a bacterium, is a prokaryote—Bonneau was recently able to piece together how the genes affected one another’s expression, enabling him to map the organism’s “control circuit” as if it were a machine. In the process, he found something surprising: Instead of generating completely different responses to external stimuli like light and toxic chemicals, “the archaeon takes those environmental stimuli and puts them into the same integrator,” he says. “There’s not an infinite number of responses.” Knowing the limited range of behaviors that microorganisms display, he adds, will prove a big help in engineering them to churn out drugs and biofuels. —Elizabeth Svoboda

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