A living cell is like a bustling city: cargo moves continuously along its streets, and traffic flows are regulated so that everything needed arrives on time. But while you can watch a city from a helicopter, the cell's interior has long been observable only through a narrow slit — the microscope showed just a flat picture. In the new study, researchers expanded the view to full three-dimensional space.
They developed a method that analyzes a series of volumetric images of a cell taken at short intervals. By comparing how the picture changes from frame to frame, the algorithm calculates where and how fast particles move, how quickly they mix by diffusion, and how densely they are packed at each point. The method was validated on synthetic data, where the motion parameters were known in advance, and on microscopic plastic beads in a gel. The results matched expectations, confirming the approach's reliability.
Next, the method was applied to mitochondria, the cell's powerhouses, inside a growing camellia pollen tube. It turned out that transport is organized as two-way traffic: in the central part of the tube, mitochondria drift in one direction, while near the edges they move in the opposite direction, and the backward flow is faster. Moreover, in the center, particles are denser and move more orderly, whereas at the periphery they scatter and mix more actively. This pattern resembles a fountain: the jet shoots upward, then spreads sideways and falls down along the edges.
The new method can visualize not only mitochondria but also smaller vesicles that carry substances within the cell. There are about ten times more of them than mitochondria, but the flow pattern is similar. This suggests that intracellular transport follows common principles, which can now be studied in detail. Understanding these processes is important for medicine: disruptions in intracellular transport are linked to neurodegenerative diseases, such as Alzheimer's. Perhaps the new tool will help detect such abnormalities earlier.
A camellia pollen tube grows at about 1 centimeter per hour, and thousands of particles move in opposite directions inside it simultaneously.
In the film 'Fantastic Voyage', a crew in a miniaturized submarine travels through the human bloodstream — the new method lets us look inside a cell without shrinking, simply by analyzing light from a microscope.