An international team of scientists from Argentina, the United States, and the United Kingdom has made a surprising discovery by observing the changes that occur inside neurons that regulate the biological clock. Published in the journal Current Biology, the research was conducted on Drosophila melanogaster, a key model organism that shares biological mechanisms with humans. Using volumetric electron microscopy, a technology not available in Argentina, the researchers were able to see for the first time how the shape, number, and volume of mitochondria change throughout the day. It turns out that in the morning, the mitochondria in the 'clock' neurons are small, round, and vigorous, but by night they become elongated and fuse. 'This speaks to how the physiological state of the cells changes, and this is something no one had seen before,' explained the study's leader, Fernanda Ceriani. The researchers also found that the number of synapses (connections between neurons) and the probability of neurotransmitter vesicles fusing with the membrane to be released change over the course of a day. This discovery opens a new line of research and helps to understand the importance of respecting sleep-wake cycles. A malfunction in this entire system can lead to weakened immunity, insomnia, depression, diabetes, and reduced cognitive performance. 'When you understand that this process is happening, you can somehow comprehend why it's so important to respect sleep and wakefulness cycles,' Ceriani concluded.
