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Cells Put a Price Tag on Sensing Their World
A new model shows how cells could optimize biochemical sensing by balancing information gained against energy spent.
A cell never senses its environment directly. Instead, it receives a noisy stream of molecular cuesâchemical markers binding to receptors, enzymes switching states, and messenger molecules appearing and disappearing. Extracting a meaningful signal from these fluctuations can improve survival, but doing so comes at a cost. Maintaining chemical currents and producing readout molecules consume energy. Giorgio Nicoletti of the Abdus Salam International Center for Theoretical Physics in Italy and his colleagues now show how achieving optimal sensing performance requires a balance between gained information and spent energy [1]. Their key idea is to formulate this balance in terms of quantities that can be estimated from statistical observations rather than from hard-to-measure microscopic forces.
Neuron cell bodies switch gene programs to steer growing axons, study finds
A new discovery by neuroscientists at Brown Universityâs Carney Institute for Brain Science challenges long-held beliefs in neurobiology about how neurons extend axons to reach their targets.
Published in Proceedings of the National Academy of Sciences, the findings provide what the authors call a âgenetic atlasâ of neuronal development, as well as a potential step forward for understanding how to repair broken neural connections in conditions such as stroke and spinal cord injury.
âWe discovered that during development, neurons turn on and off entire groups of genes that allow their axons to grow through different sections of their path,â said study author Alexander Jaworski, an associate professor of brain science at the Carney Institute. âThatâs surprising.â
A famous galaxyâs black hole has been hiding its most violent behavior
Astronomers have found that a nearby galaxyâs black hole is blasting out a far more powerful and hidden gas outflow than previously realized. Studying NGC 1068, a well-known galaxy with an actively feeding black hole at its center, researchers combined new infrared observations with existing data to map how the black holeâs energy is reshaping the surrounding gas. The results are reported in a paper published Aug. 6 in Astronomy & Astrophysics.
Ultracold cesium atoms reveal Bethe strings predicted nearly a century ago
In 1931, physicist Hans Bethe predicted that, in certain one-dimensional quantum systems, particles can bind together to form multi-particle states known as Bethe strings. Unlike ordinary molecules, which are held together by chemical bonds, Bethe strings arise purely from interactions between particles and exist only in one dimension. For decades, Bethe strings remained primarily a theoretical concept.
Now, almost a century after Betheâs prediction, researchers from the University of Innsbruck, in collaboration with theory teams from the Department of Experimental Physics at the University of Amsterdam and the Technical University of Munich, have created and observed these multi-particle bound states in an ultracold gas. Their findings are published in Nature Communications.
The experiment begins with a cloud of cesium atoms cooled to temperatures only a few billionths of a degree above absolute zero. The researchers then divide the cloud into several thousand narrow, one-dimensional tubes. Inside these tubes, the atoms can move essentially only along a single direction. The interactions between the atoms can be precisely controlled. By tuning the interactions between the atoms from repulsive to attractive, they can make the atoms bind together. Instead of simply collapsing, the atoms form bound states of different sizes, including larger clusters containing six or more particles.
