Sleep increases chromosomal movement and enables effective DNA repair in nerve cells

Sleep increases chromosomal movement and enables effective DNA repair in nerve cells

Why do people spend a third of their lives sleeping? During evolution, sleep remains a universal and vital process for all organisms with a nervous system, including invertebrates such as flies, worms, and even jellyfish. 

In a new study published in the journal Nature Communications, researchers revealed a new and unexpected role in sleep that they think can explain how sleep and sleep disorders affect brain function, aging, diseases and brain disorders.

Using three-dimensional imaging techniques and continuous real-time imaging of zebrafish, the researchers managed to define sleep at the resolution of a single chromosome and show, for the first time, that individual neurons need sleep to perform cell maintenance.

DNA damage can be caused by many processes, including radiation, oxidative stress, and even electrical activity of the neurons. The current work shows that during observations, when the movement of the chromosome is low, damage to DNA accumulates consistently and can also pose a health risk.

According to the researchers, one of the functions of sleep is to increase the movement of chromosomes and restore the levels of DNA damage to normal levels in each neuron. Apparently, the process of DNA maintenance in nerve cells is not efficient enough during the wake period and therefore requires a sleep period to function properly. "It's like potholes and holes in the road," says the senior author. "Roads are gaining wear and tear, especially during rush hour hours, so it's most convenient and efficient to fix them at night when there is little traffic."

The senior author describes the accumulation of damage to DNA in nerve cells in the brain as "the price of wakefulness." The authors have suggested that sleep unites and synchronizes the maintenance of DNA in individual nerve cells.

Their discovery was achieved thanks to the unique characteristics of zebrafish. Since the fish are transparent and the structure and function of the brain is similar to humans, zebrafish is a perfect organism in which the research team can study the activity of a single cell in a living body under physiological conditions. Using a high-resolution microscope, the movement of DNA and nuclear proteins inside the cell can be observed while the fish are awake and asleep, and the researchers were particularly surprised to find that chromosomes move more at night when the body sleeps.

The results showed that the chromosomal movement is a possible sign of the definition of sleep in a single cell, suggesting that the rehabilitation and maintenance of the cell nucleus are done during sleep. "We found a causal relationship between sleep, chromosome dynamics, neural activity, damage and repair of DNA with physiological relevance to the entire organism," said the senior author. "Sleep provides the opportunity to reduce the damage accumulated in the brain during waking hours."

"Despite the risk of lack of alertness to the environment during sleep, including threats from predators, animals ranging from jellyfish to zebrafish and humans need to sleep to allow their neurons to efficiently maintain DNA, which may be the reason why sleep has evolved so well in the kingdom "Says the senior author