Science at the speed of water
Researchers have revealed for the first time how fast water molecules must interact with proteins that make up living organisms in order to support life. For decades, the time scale on which the water-protein interaction works has been debated, with guesses ranging from a nanosecond to a picosecond. Using ultra-fast laser pulses to take snapshots of water molecules moving around a common bacterial protein, researchers inserted a molecule of tryptophan into the protein as an optical probe, and then measured how water moved around it. The laser studies of the protein while it was immersed in water revealed that when far from the protein, water molecules moved around each other at typically fast speeds, each movement requiring only a single picosecond. Water near the protein, however, formed several layers that flowed at slower speeds. In the innermost layer, each interaction of a water molecule with the protein required at least 100 picoseconds to complete. Researchers concluded that water, when supporting life on a molecular level, must move a hundred times slower than when alone. They propose that the necessary slowing down of water is nature’s way of ensuring every water-protein interaction is right. If water had to speed up in order to interact with proteins, a bottleneck would appear in everyday biological processes that organisms cannot afford.
Source: PNAS
-Abigail Slinger
Slow it down, baby
By measuring electrical activity in the brains of pre-surgical epilepsy patients, researchers have found the first evidence that slow brain oscillations, or theta waves, “tune in” to the fast brain oscillations, called high-gamma waves. Fast oscillations signal the transmission of information between areas of the brain and its pairing with slow oscillations allow widely separated regions of the brain to coordinate a single complex activity. When doing simple tasks, like listening to a list of words, researchers found that the slow, theta oscillations in the hearing area of the brain became coupled with the fast, high-gamma oscillations in the same area. During complex actions, different brain regions “tune in” to the high-gamma oscillations. They transfer information between regions more easily when different areas oscillate together at the same theta frequency. Researchers propose that high-gamma waves regulate information input and output from a small region of neurons while theta waves coordinate different regions of the brain. This could be a way for the brain to connect low-level actions to high-level goals.
Source: UC Berkeley news service
-A.S.
