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A team of biologists, physiologists, and neurologists has discovered an important regulatory DNA molecule that is responsible for the amplitude of circadian rhythms. So far, the study was conducted only on cultured mouse cells, but scientists are confident that a similar gene exists in humans.

Circadian rhythms are 24-hour cycles that run in the background so that a person can perform basic functions. One of the most important and well — known such rhythms is the sleep-wake cycle. The various systems of our body follow circadian rhythms that synchronize with the "master clock" in the brain. They are directly affected by environmental signals, especially light, so the biological clock is tied to the change of day and night.

With proper coordination, the circadian rhythm contributes to a full and restorative sleep, and when it is disturbed, there are serious problems with night rest, including insomnia. In addition, circadian rhythms play an important role in various aspects of physical and mental health. These cyclical fluctuations in the intensity of various biological processes are not only found in humans: almost every living organism — from mammals and plants to some microorganisms and fungi-has an internal clock.

Scientists have long been concerned with the question: but how do circadian rhythms work? And thanks to the research of a team of biologists, physiologists and neurologists from the Virginia Institute of Technology, the University of Texas Southwestern Medical Center (USA) and Kyoto Medical University (Japan), we are one step closer to solving the mystery.

When the Human Genome project was launched in 1990, coordinated by the U.S. Department of Energy and the National Institutes of Health (its goal is to determine the sequences of the three billion base pairs that make up human DNA, and identify approximately 20-25 thousand genes), scientists were sure that most of our genome consists of "traditional" genes. After all, they were thought to be responsible for unique traits, such as eye and hair color, height, weight, and so on. But the experts were wrong.

"It turned out that only two percent of our genome contains" traditional "genes, and the rest, apparently, are "non-traditional". There has been debate about whether these unconventional genes are important: some believe that this is junk DNA, while others say that such genes also have important functions, " said Shihoko Kojima, associate professor of biological sciences at the Virginia Tech College, the lead author of the work. But a growing body of research suggests that non-traditional genes — at least some of them — are important for various biological processes, such as neuronal activity, immune function, cell differentiation, and the development of diseases, including cancer, neurodegeneration, and congenital genetic diseases.

And, as scientists have found out, one such unusual gene can control the circadian rhythms of the body. The research team identified a new Per2AS gene in mouse samples in a Petri dish: it controls the sleep and wake cycle, is responsible for the amplitude of rhythms, but does not encode a sequence of proteins, that is, refers to the so-called junk DNA. "The work lasted nine years. It was difficult to figure out what the purpose of this gene was, since it was non — coding, " Kojima added. "Scientists have accumulated a lot of knowledge and tools to figure out the function of traditional genes. However, these tools are not so easy to apply to non-traditional genes like Per2AS, because most of the tools were created on the basis of unique characteristics that are common to traditional genes."

According to the authors of the study, the same gene is definitely present in humans. But it is not yet clear whether the human version of Per2AS has the same functions as the mouse version. "Most organisms living on Earth have circadian rhythms, as this is an internal synchronization system important for adapting to the daily changes in the environment, it is caused by the rotation of the Earth. The circadian rhythms of humans are not too different from the biological clocks of rodents or insects, " the scientists noted. Now they plan to study Per2AS in a model of living rodents and find out if it is present in the organisms of other creatures.

The article is published in the journal Genes & Development

Image © Stefan Klein
Source: naked-science.ru, sci-dig.ru