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News from the Physical Sciences


Real-time readout of neurochemical activity

Scientists have created cells with fluorescent dyes that change color in response to specific neurochemicals. By implanting these cells into living mammalian brains, they have shown how neurochemical signaling changes as a food reward drives learning.

These cells can detect small amounts of the neurotransmitter dopamine with fine resolution in both location and timing. Dopamine has long been of interest to neuroscientists for its role in learning, reward, and addiction.

“Dopamine serves as the key indicator during almost all aspects of learning and the formation of new memories,” said physics professor David Kleinfeld, who directed the work. “Disruptions to dopamine signaling lie at the heart of schizophrenia and addiction.” More.

structures of switches in hepatitis C and Seneca Valley virus

Viral switches share a shape

A hinge in the RNA genome of the virus that causes hepatitis C works like a switch that can be flipped to prevent it from replicating in infected cells. Scientists have discovered that this shape is shared by several other viruses—among them one that kills cancer cells.

That’s Seneca Valley virus, which seems harmless to healthy human cells but lethal to cancer stem cells.

<p">Chemistry and biochemistry professor Thomas Hermann’s research group has determined the molecular structure of this critical switch in the Seneca Valley virus and found that it matches the L-shaped switch in hepatitis C virus, which his group had previously described. Read more.
micrograph of self-assembled cell membranes

Cell membranes self-assemble

A self-driven reaction can assemble phospholipid membranes like those that enclose cells

Neal Devaraj, a chemistry and biochemistry professor at UC San Diego, leads a research team that develops and explores new reactions that can trigger the formation of membranes, particularly the spheres that characterize membranes that enclose vesicles and cells.

The new process they have just described is specific and non-toxic, and can be used in the presence of biomolecules one might want to study within artificial cells. The technique could also be used to assemble packets for drug delivery. 

Read more.


Moth Math

The way in which male moths locate females flying hundreds of meters away has long been a mystery to scientists.

Moths use pheromones to locate their mates. Yet when these chemical odors are dispersed in a windy, turbulent atmosphere, the insects still manage to fly in the right direction over hundreds of meters with only random puffs of their mates’ pheromones spaced tens of seconds apart to guide them.

Now physicists led by Massimo Vergassola have figured out the mathematics underlying this feat. More.

polarized CMBEarly success for POLARBEAR

Cosmologists have made the most sensitive and precise measurements yet of the polarization of the cosmic microwave background.

The report marks an early success for POLARBEAR, a collaboration of more than 70 scientists using a telescope high in Chile’s Atacama desert designed to capture the universe’s oldest light.

POLARBEAR measures remnant radiation from the Big Bang, which has cooled and stretched with the expansion of the universe to microwave lengths. This cosmic microwave background acts as an enormous backlight, illuminating the large-scale structure of the universe and carrying an imprint of cosmic history. Read More.

Data-sharing deal struck with drug companies

Pharmaceutical companies will collaborate with researchers at UC San Diego to provide previously unreleased proprietary data for drug discovery through a new $3.7 million effort funded by the National Institutes for Health. Rommie Amaro and Victoria Feher in the department of chemistry and biochemistry and Michael Gilson, professor of pharmacy, will lead the project. The data provide atomic details of drug mechanisms and will be used to improve computer-aided drug-design methods and thus accelerate drug discovery. Read More.

UV light splits atoms of nitrogen gas

Nitrogen fingerprint in biomolecules could be from the early sun

Chemical fingerprints of the element nitrogen vary by extremes in materials from the molecules of life to the solar wind to interstellar dust. Ideas for how this great variety came about have included alien molecules shuttled in by icy comets from beyond our solar system and complex chemical scenarios. Now experiments using a powerful source of ultraviolet light have shown that no extra-solar explanation is needed and the chemistry is straight forward. Read more.

enzymes modify DNA and the proteins it wraps around

Program predicts placement of chemical tags that control gene activity

Biochemists have developed a program that predicts the placement of chemical marks that control the activity of genes based on sequences of DNA. Read more.

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