A group of researchers led by Dr. Gad Asher from the Weizmann Institute deciphered the secret of the biological clock
For every time and a time for every object under heaven, said King Solomon, the wisest of all men: a time to give birth and a time to die, a time for war and a time for peace. Modern science specifies and says that there is also a time to get up - at six in the morning, when the metabolism starts to work; Time to love - at eight in the morning, when sex hormones are approaching their peak; When to visit the dentist - at two in the afternoon, when the sensitivity to pain decreases; And the time to avoid driving - at two in the morning, when the body is preparing for deep sleep.
This meticulous schedule is determined by internal biological clocks, which operate in a cycle of about 24 hours, and are called "circadian clocks", a term derived from the Latin phrase circa diem, which means "about a day". These watches monitor the daily fluctuations in heart rate, blood pressure, kidney function, body temperature, sleep, sensory sensations and hormone secretions. The main circadian clock found in the brain synchronizes the many clocks scattered in the periphery - not only in every organ of the body, but in every one of its cells. "Our body is actually a huge collection of microscopic clocks, all of which tick in a timed fashion," says Dr. Gad Asher, who recently joined the biological chemistry department of the Weizmann Institute of Science. "Furthermore, the amazing thing is that all these clocks function well - even when the same cells are grown in culture."
Dr. Asher's main goals are to discover why we need circadian clocks, and how they work. Science is not yet able to answer these questions, but it is clear that the clocks are essential. First, studies show that people who work in shifts are at an increased risk of getting cancer, diabetes, and obesity, and suffer from increased aging, probably because their circadian clocks are disrupted by working hours that do not correspond to a normal day and night cycle. Another sign of the importance of clocks: they have been preserved over millions of years of evolution, from plants and bacteria to humans, which usually indicates that nature "considers" the mechanism to be essential. In addition, 15% of all our genes obey the circadian rhythm. "This is a very high number. This means that many processes in our body occur in a completely different way at different times of the day," says Dr. Asher.
A clear example of this type of process was discovered by chance - as often happens in science - in the laboratory of Prof. Oli Shibler at the University of Geneva. Several years before Dr. Asher came to this laboratory to conduct his post-doctoral research, Prof. Shibler's research group discovered that it is possible to produce particularly large amounts of a protein called DBP from liver cells. But, after the scientists had already published the findings in a prestigious scientific journal, a serious thing was discovered: they repeated the same experiments, but failed to produce the protein. The members of the group panicked, but the mystery was quickly solved: it turned out that the original experiments were carried out by a student who used to arrive at the laboratory at six in the morning, because he was used to getting up early at his family's house - a family of Swiss farmers. On the other hand, the second round of experiments was carried out by an American student who used to stay up until the morning hours, sleep during the day, and arrive at the laboratory only at two in the afternoon. The protein in the experiments was among the proteins controlled by the circadian clock: in the morning the cells secreted it in quantities 100 times greater than in the afternoon. The fascinating discovery led to a long series of studies on circadian clocks in Prof. Schibler's laboratory in Geneva. "Geneva is a world center not only when it comes to Swiss watches, but also in the field of circadian clocks," says Dr. Asher.
One of the main questions that Dr. Asher plans to investigate is related to the control of the circadian clocks. It is known that the central clock in the brain adjusts daily through the daily cycle of darkness and light. But in other organs, the clocks are sensitive to the times of eating, so they seem to receive targeted signals according to the metabolic state of the cells. While working in Prof. Shibler's laboratory in Switzerland, Dr. Asher discovered that the protein called SIRT1, which plays a key role in cell metabolism, also controls the activity of the circadian clocks. According to the scientific journal Cell, the discovery indicates that the SIRT1 gene is the "missing link" connecting metabolism and circadian clocks. In his new laboratory at the Weizmann Institute, Dr. Asher plans to expand the research on the interrelationships between metabolic factors and circadian mechanisms.
Dr. Asher's ambition is to find out how the circadian clocks work at the level of cells and molecules, and how the central clock in the brain synchronizes the clocks in the other organs of the body. His research is designed to answer basic questions in biology, which are related to many conditions of the healthy and sick body, starting with jet lag and sleep disorders, and ending with cancer, diabetes, obesity and aging.
Gad Asher was born in Ramat Gan, and began studying mathematics as part of a special program to promote excellence at Tel Aviv University, but later switched to medical studies. He received a medical degree with honors in 1998. Already during his medical studies he was fascinated by biological research, and spent three summers in research training at the Weizmann Institute. During his internship in internal medicine at the Sourasky Medical Center in Tel Aviv, he enrolled in a research PhD in the Department of Molecular Genetics at the Weizmann Institute of Science, which he did under the guidance of Prof. Yosef Shaul. After receiving a doctorate in 2006, he decided to devote all his time to research. He conducted post-doctoral research for four years at the University of Geneva in Switzerland, and in May 2011 joined the Weizmann Institute of Science as a senior researcher. Outside of his pursuit of science, he enjoys playing classical pieces on the piano, participating in bicycle races and mountain climbing.
14 תגובות
Can you please order an orderly division according to the time of day, which hormone is active?
The Chinese Taoists discovered the daily and annual cycle of physical and mental activity, many years ago [3000].
serious
The question of the relationship between life and time is a question that has been studied a lot. In order to answer whether the clock is "internal" they put animals (including those that live underground such as rats), bacteria, plants, etc. into a fixed lighting regime for extended periods of time, and saw that they continued to show 24 hour cycles in their behavior.
As for neutrinos - listen, in order to discover this particle the physicists had to use devices the size of a mountain because these particles do not react with almost anything, so it is not so likely that bacteria pick them up and react to them.
I believe that in the future they will find a very close connection between the rhythm set by the sun and the whiteness of everything here
From the cell atom... perhaps it is through particles such as neutrinos. It makes sense that there are other bodies or energies
/Powers that also influence.
It seems a little wrong to me to say that the biological clock in the living plant was "internal".
to Ernest
If you put a bird in total darkness for a long period of time you will see that its activity goes up and down in cycles of just under 24 hours. Also, you will see changes throughout the year. In an experiment done with songbirds it was shown that they become active at night twice a year, and they indeed migrate at night, twice a year.
And in addition, of course there is an adjustment of the clock using light, as I mentioned above.
From Chalk
The bird as an example does not wake up or fall asleep according to an internal clock or another clock but according to the state of the sun
which changes from day to day. It seems that every morning some kind of adjustment or adjustment is made in the internal clock
to the sundial in everything related to day-to-day activities.
Whereas seasonal systems such as reproduction have a clock in it that is adjusted according to the rhythm or state of the seasons and/or climate.
It is very good not to blindly copy what the Weizmann Institute publishes!
The title is just a bad joke. The "secret" of the molecular clock was deciphered about 2 decades ago 🙂 You missed the mark a bit, dear researcher 🙂
What the same researcher claims to have discovered is a gene (one!! to say that it is the missing link is again an exaggeration, but not as terrible as the previous ones :)) through which metabolic processes control the activity of the circadian clock.
Yoel and Ernst,
The clock works through 2 genes whose products silence each other's expression, so their level fluctuates in a cycle of a little less than 24 hours. In addition, the effect of various factors on their level can act to readjust the clock. In flies, for example, one of these proteins is sensitive to light, so lighting at changing hours will cause its breakdown and change the cycle.
point,
The assumption that a trait you see is evolutionarily optimal is a very popular but misleading claim. Evolution works within the existing constraints, so a trait can be the result of different constraints and not of natural selection in its favor. As Yigal pointed out: the clock may not be enough to develop because other things need to be developed first, or the baby simply gets hungry or stomach pains can cause awakenings despite the clock. In short - do not assume that each feature is the fruit of independent evolution.
I did not find any direction in the review either to the question of the essence of the mechanism, what determines its internal rhythm [in my watch it is the quartz] nor to the synchronization mechanism between the external phenomena [light and darkness] which themselves also change according to the seasons and geography and not between the elements.
Let's hope they find it. By the way, I heard about a pharmaceutical project/experiment in which they adjusted the taking of the drugs to the state of the biological clock and the maximum absorption capacity, and thus managed to lower the dose in tens and in certain drugs by hundreds of percent. It seems elementary compared to a figure of 100 times the activity of the liver. It is clear that a drug that is neutralized by it can overcome the resistance more easily when it is 'sleeping' and vice versa a drug that spurs it on when it is active.
health and happiness
From an evolutionary point of view, there is a clear advantage to waking up at night... Why is it unacceptable that this should be explained?
If we take a bird as an example, then throughout its life, it works in coordination with "clocks" outside its body, such as the sun, moon, weather, and the seasons. This means that its body operates according to an irregular, unstable schedule that never repeats itself. This affects Each of the processes mentioned in the article hunger, hormones, sleep and more.
The biological clock may be ticking at a constant rate, but unlike our clocks, it chimes to illuminate the old
according to the state of the sun which changes from day to day. and calls the body to start producing hormones at a certain point in time
related to the seasons that change every year and in their length, beginning and end..
'Parts of the brain' of course
point,
In the article it was stated that the circadian clock in the brain synchronizes the other clocks in the body. There are parts of the brain whose development matures at a relatively late age (one of the differences between humans and other animals) and it is possible that the part responsible for the circadian clock in the brain is one of them.
Sounds fascinating!
Why don't babies have a 24-hour cycle (that's what I heard)?
It seems that in the past there was an evolutionary advantage to an irregular cycle (waking the parents randomly and driving away predators?)