Research Briefs
Bacteria Hasn’t Changed Its Password in 2.7 Billion Years
Despite 2.7 billion years of evolution, bacteria are still using the same “password” to initiate the process for making spores. Researchers, led by the Department of Biological Sciences’ Dannie Durand, used computational and experimental techniques to study how the signaling network that causes Bacilli and Clostridia to form spores evolved since the bacteria diverged from a common ancestor. The researchers found that contrary to the prevailing theory both conserved a four-protein signaling network that starts sporulation. Their results were published in PLOS Genetics.
Dark Matter on the Move
An international research team, including the Department of Physics’ Matthew Walker, found evidence that dark matter can be heated up and moved around as a result of star formation in galaxies. The team measured the amount of dark matter at the center of 16 dwarf galaxies and found that the galaxies that had stopped forming stars had higher dark matter densities than those that were still forming stars. This difference in densities can be attributed to “dark matter heating,” where strong winds from star formation force gas and dust away from the heart of a galaxy, affecting how much gravity is felt by the dark matter within the galaxy. The results, which were published in the Monthly Notices of the Royal Astronomical Society, take researchers a step closer to understanding what dark matter is.
ONLINE CONTENT: Slide graphic to view simulation vs. real data.
The Math Inside Your Cup
Imagine the curve formed inside a cup where water, glass and air meet. It’s something we encounter every day, but the dynamics of the curve are notoriously difficult to mathematically model due to the complex interactions between the liquid, solid and gas.
Research published last year by Associate Professor of Mathematical Sciences Ian Tice in the journal Archive for Rational Mechanics and Analysis builds on more than 200 years of research on this concept. Tice, along with Brown University Professor Yan Guo, has studied a new model of this three-phase interface that more realistically represents freely moving liquid and air in a solid cup, and derived mathematically the rates at which these different substances reach equilibrium when a cup containing liquid is set down to rest.
Healing Broken Bones with Chemistry
Graphite, the same substance that fills our pencils, can be employed to repair severe bone fractures more effectively than current technologies. A research team, led by the Department of Chemistry’s Stefanie Sydlik, modified graphene with calcium phosphate to create a degradable material that mimics the composition of bone. The material can be used as a rejection-resistant scaffolding that instructs the body’s stem cells to heal major bone fractures. The study was published in the Proceedings of the National Academy of Sciences.
Capture and Convert
A new material may be able to capture carbon dioxide and turn it into a commercially useful substance. Working with the Pittsburgh Supercomputing Center and its Bridges system, a University of Pittsburgh team modeled two “metal oxide framework” materials that simulated removal of carbon dioxide from exhaust gas. The material also converted it into formic acid, which can be used to make products like methanol fuel. If the material works as well in the lab and factory as it does in the computer, it could fundamentally alter the economics of limiting human CO2 release and avoiding climate change.
Researchers Discover What Pneumococcus Says to Make You Sick
Organisms worldwide communicate in their own unique ways: humans use words, bees dance, and fireflies glow. What if bacteria also have their own language? If we understood that syntax, could we simply ask the bacteria to stop making us sick?
These questions are at the core of Associate Professor of Biological Sciences Luisa Hiller’s research. In a study in PLOS Pathogens, Hiller’s team identified a molecule that plays a key role in bacterial communication and infection. Named BriC, it signals when pneumococcus should produce more biofilm during a certain metabolic state.
“We’re at the very beginning of the dictionary,” said Hiller. “We will continue to dig into the meaning of BriC, and related bacterial words, as a means to manipulate bacterial language and control disease.”
Molecular Converter Switches Genetic Information from Right- to Left-Handed
Professor of Chemistry Danith Ly and colleagues have developed a molecular converter that can change genetic information from right-handed to left-handed and vice versa. The converter could be an essential component for molecular computers, including one that could be used to predict infectious disease outbreaks worldwide.
Molecular computing uses molecules like DNA as circuit components, and generally requires living hosts; however these DNA-based components can inadvertently bind with the living host’s genetic material.
In research published in Communications Chemistry, Ly introduced a peptide nucleic acid-based converter that could easily switch genetic information from its normal right-handed helical confirmation to a left-handed version. Researchers could use this left-handed molecule in molecular computing to prevent it from binding with the host’s DNA.
Neurons Reliably Respond to Straight Lines
Single neurons in the brain’s primary visual cortex can reliably detect straight lines, even though the cellular makeup of the neurons is constantly changing, according to a study led by Associate Professor of Biological Sciences Sandra Kuhlman and published in Scientific Reports.
A new imaging technology called two-photon microscopy allowed Kuhlman’s lab to visualize hundreds of neurons at once in the primary visual cortex of a mouse model. Over a two-week period, the mice were exposed to an extensive range of stimuli, including lines of varying thickness.
They found that some neurons were unstable in how they responded to thickness, while maintaining their original selectivity to line orientation, indicating that individual neurons can continually encode particular visual features while still being able to adapt to others.
Gaia Spots a ‘Ghost’ Galaxy Next Door
An international team of researchers, physicists Sergey Koposov and Matthew Walker, used data from the European Space Agency’s Gaia satellite to discover an enormous galaxy lurking in the outskirts of the Milky Way. Antlia 2 (Ant 2) had previously escaped detection due to its astonishingly low density and perfectly chosen hiding place behind the Milky Way’s disk.
Ant 2 is unlike any of the other known dwarf satellites of the Milky Way, since it is much larger in size and gives off much less light. One possible reason for the unusual properties of Ant 2 is the gravitational interaction between the Milky Way and the dwarf galaxy, which exerts strong tidal forces on the dwarf galaxy.
Chemists Manipulate the Quantum States of Gold Nanoclusters
Researchers led Professor of Chemistry Rongchao Jin have found a way to increase the lifetime of the quantum states of gold nanoclusters by three orders of magnitude, which could improve solar cell and photocatalysis technologies.
The team altered the configurations of atomically precise gold nanoclusters, finding that a 30-atom nanocluster, with a hexagonal close-packed structure, had a quantum lifetime of one nanosecond, while a 38-atom nanocluster with a body-centered cubic structure had a much longer lifetime of 4.7 microseconds. The findings were published in Science.
Extending the lifetime gives researchers ample time to extract the absorbed light energy from the nanoclusters, and can also be used to increase the efficiency of visible light-based photocatalysis used to convert solar energy storage into chemicals.
Computer Simulation Shows How Dynamin Releases Vesicles from the Cell Membrane
A computer simulation developed by biological physicists has determined how the protein dynamin works with the cell membrane to bring essential molecules into the cell.
The membrane has the important job of determining what molecules should be allowed into the cell and bringing those molecules into the cell’s interior. When this process doesn’t work, vital molecules are stopped at the membrane and are unable to perform their job in the cell.
In eLife, a team led by Professor of Physics Markus Deserno details a computational model that simulates the geometry and elasticity of the lipid membrane and dynamin. Their findings can be used to better study the role the process plays in dynamin-related diseases like Charcot-Marie-Tooth disease.
‘Gamechanger’ in Natural Product Structure Determination
A “gamechanger” set of methods published in the journal Nature Protocols by a team, including Chemistry Professor Roberto R. Gil, shows how to unambiguously determine the three-dimensional structure of molecules with nuclear magnetic resonance (NMR) spectroscopy.
For complex flexible organic small molecules, the data obtained from conventional NMR analysis can often make it difficult or impossible to pin down the exact structure of compounds.
To overcome this problem, Gil and others have worked to develop gels that swell in different organic solvents into which samples can be placed. When compressed or stretched, these gels help align the molecules relative to the axis of the magnetic field. The paper also tackles how to best acquire NMR data and include them in the structure determination process.