An endless story: genes that work after death
On the eve of a bright holiday, free from ideology, religion, and the cult of personalities, it is customary to recall miracles and tell incredible stories. Christmas stories - not necessarily about the triumph of justice, not about the battle between good and evil. They are very bright and talk about the miracles that happen in everyday life with the most ordinary creatures. So we have prepared for you a New Year's fairy tale about ... genes. The most common creatures in the laboratory are zebrafish mice and fish. The first one was even given a monument for their honest service to people, and the second, even without a monument, silently donate their large transparent embryos to scientists so that they can explore the general laws of the development of vertebrates. Scientists from Europe and the United States tried to find out what happens to mice and fish after death. Once, the laboratory calibrated a method for measuring gene activity in animal corpses, and this is what came of it.
Suddenness, irrationality, unpredictability, - at all times a halo of mystery soars around death. To find the source of eternal life, the great mystifiers invented the philosopher's stone, tried to get the absolute rings, and even went on trips in search of unicorns and the Undying Lands. The common people saw in death both payment for sins, and a gift or redemption. Speaking objectively, death is the cessation in the body of all biological and physiological processes. Due to the mystical image of death, the establishment of the fact of death for a long time remained a difficult task for humanity (for example, if the patient is unconscious or in a state of alcohol or drug intoxication).
There are two types of death: natural and violent. The “turning off” of the organism in both cases proceeds according to the standard algorithm, but the duration of the stages varies. This also applies to the result: with resuscitation performed on time, a person can stay alive. Before dying, the organism — here you can talk both about a person and about any other warm-blooded vertebrate animal — is in agony. First, pressure is greatly reduced, breathing is disturbed, sensitivity and reaction to what is happening are dulled, and then agony occurs. At this stage, on the contrary, all processes are activated, this is the “last hope” for salvation on our own. The pressure increases, the muscles begin to decline, the metabolism starts. At the same time, consciousness may return for a while, but breathing, ventilation of the lungs, is absent, because the contraction of muscles is not coordinated. As soon as the heart, the respiratory system and the central nervous system fail, they are diagnosed with clinical death.
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Fears that you will be slaughtered alive in a coffin or will begin to cut organs before you emit the last breath, are not very relevant now. There is a general criterion for the diagnosis of death - brain death. The lack of reflexes, motor and respiratory activity is evidence in favor of the final departure from life. With brain death in the organ itself, irreversible changes will soon begin, which lead to degradation. Alas, the world standard for diagnosing brain death does not yet exist, so the fact that the criteria and methods of this procedure differ in different states is certainly alarming.
The logical continuation of the well-known metaphor that represents a living organism in the form of a machine with the most complicated mechanism will be the assumption that after death the work of everything gradually fades away: there is no “fuel” (oxygen and nutrients), the metabolism slows down and gradually all the “engines” stop work However, in biology, it is important not to replace reality with a beautiful metaphor or convenient model. That is why the collaboration of scientists under the guidance of the microbiologist Peter Noble during the working hypothesis: “Probably, the genes stop working after death” decided to set up an experiment to check what actually happens to the genes. Indeed, exploring death, you can learn quite a lot about life!
"Gene works" - the status of the DNA segment from which information is read using various cellular machines. At the same time, molecules are formed, which are called the common word “transcripts”. A transcript is a collection of all transcripts that are present in a sample. Currently, one of the main methods for measuring gene activity is the analysis of transcriptomes of various tissues. Unlike the genome, which is stable and the same in all cells of the body, the transcript can vary considerably depending on the environmental conditions, the state of the cell and its origin.
To study empirically death, you need to kill animals. Such work requires the preliminary passage of many special commissions on bioethics. The experiment of Peter Noble’s team consisted of the following: the animals were killed at a time and then placed in a familiar environment. At the same time, both in the aquarium and in the air, circulation of water or air was maintained. In order to conduct further research on samples, several bodies were taken with a certain frequency and frozen in liquid nitrogen. Such a collection of "samples" was carried out within 48 hours from the moment of death of the mice and 96 hours from the moment of the death of the fish. As a result of the analysis of the so-called thanatatranscriptome (from the Greek “thanatos” - death), 1063 genes were anotable. The activity of most of them after death decreases sharply, but some of the DNA sites do not know anything about death and continue to work. Some of the examined genes remained active for 4 days after the death of the animal.
Researchers emphasize: their data show not “residual activity”, but the independent work of genes after the death of an animal. In confirmation of this, they cite the data of quantitative analysis of transcripts. The change in the volume of molecules in tissues occurs in different ways. As a result of qualitative analysis, functional characteristics of individual groups of genes that work in the cells of a dead body (from the point of view of the processes in which they participate) were obtained: stress response, internal and adaptive immune response, inflammatory process, cell death, transport and regulatory processes, oncogenesis as well as embryonic development.
In both organisms, the peak of the work of these genes fell on the day after death. The researchers explain this as an attempt by the body to restore balance in the absence of resources. We are talking about such genes as the stress response, such as heat shock genes, hypoxia, and other types of reactions, such as oxidative stress.
Those who believe in life after death, realize that the human body from the mortal container for the soul becomes refined purgatory for various living organisms. Bacteria, worms, and then arthropods, perhaps even bigger animals, in general, everyone who does not disdain will become the life that fills the body of a large mammal after death. In this case, the fact that after the death of the genes of the immune response is activated is quite logical. Despite the fact that the empire of the human body is already dead, individual cells continue to exist and launch molecular machines into battle, activating the genes of the immune response and inflammation.
In the cell there is a well-established system of launching your own “death machine”. This is required in cases where it becomes clear that "something went wrong." Starting with the expression (generation of a transcript) of one of the genes, a cascade of proteins starts up, which leads to cell death. The process of programmed cell death is called apoptosis. It was not possible to establish any general patterns of the work of apoptotic genes in both types of organisms, but it was noted that they are actively working in both.
It would seem, why, in the absence of a functioning organism, would it be necessary to transfer ions, proteins or signaling molecules from a cell to a cell? Why "fold" DNA segments? According to the observations, the majority of such genes in the corpses of fish ceased their work 24 hours after death, while the transport genes of the cadavers of mice continued to work for 2 days.
There are genes in the world's genetic databases that are listed as “oncogenes”. They get such a “label” if it has been noticed that malignant neoplasms develop during their work. The composition of these genes and the characteristics of work vary greatly in organisms.
Perhaps the most unexpected finding in this experiment is the work of the genes that are responsible for the early stages of embryonic development. Surprisingly, after death, the genes that worked at the moment when the dead body was a fertilized egg or egg cell and just created the muscles or the nervous system are included. Scientists admit to the article that they are very surprised by the discovery of these genes, and offer two versions of the explanation of what is happening. On the one hand, maintaining the “silence” of these genes can be an active process, which ceases with the death of general regulatory systems. On the other hand, the physiological conditions of a dead organism can remotely resemble those under which embryonic development occurs.
In addition to the games of pundits and plans for immortality in the near future, there are two serious issues that are directly related to such research. First of all, it is organ transplantation from recently deceased donors. It is known that the risk of cancer increases with organ transplantation. The most common example is skin cancer (it is possible that oncogenesis is due precisely to the work of oncogenes in dead tissue). On the other hand, in the subsequent analysis, you can create a method for accurately determining the time of death based on the composition of the tanatotranscriptome.
So, dear friend, it turned out that even in ordinary mice and fish, after death, there are more than a thousand genes. Is this not a miracle? (Is this not motivation?)
Thanks to everyone who read us and was with us this year. And we have prepared a DNA test "under the Christmas tree." Just like in the best times of our life: you tell a short interesting fact about genes or genetics (however, not necessarily in text format), and you get a DNA test as a gift. Detailed rules - by reference .
Punishment or salvation
Suddenness, irrationality, unpredictability, - at all times a halo of mystery soars around death. To find the source of eternal life, the great mystifiers invented the philosopher's stone, tried to get the absolute rings, and even went on trips in search of unicorns and the Undying Lands. The common people saw in death both payment for sins, and a gift or redemption. Speaking objectively, death is the cessation in the body of all biological and physiological processes. Due to the mystical image of death, the establishment of the fact of death for a long time remained a difficult task for humanity (for example, if the patient is unconscious or in a state of alcohol or drug intoxication).
Death by algorithm
There are two types of death: natural and violent. The “turning off” of the organism in both cases proceeds according to the standard algorithm, but the duration of the stages varies. This also applies to the result: with resuscitation performed on time, a person can stay alive. Before dying, the organism — here you can talk both about a person and about any other warm-blooded vertebrate animal — is in agony. First, pressure is greatly reduced, breathing is disturbed, sensitivity and reaction to what is happening are dulled, and then agony occurs. At this stage, on the contrary, all processes are activated, this is the “last hope” for salvation on our own. The pressure increases, the muscles begin to decline, the metabolism starts. At the same time, consciousness may return for a while, but breathing, ventilation of the lungs, is absent, because the contraction of muscles is not coordinated. As soon as the heart, the respiratory system and the central nervous system fail, they are diagnosed with clinical death.
')
Death in your head
Fears that you will be slaughtered alive in a coffin or will begin to cut organs before you emit the last breath, are not very relevant now. There is a general criterion for the diagnosis of death - brain death. The lack of reflexes, motor and respiratory activity is evidence in favor of the final departure from life. With brain death in the organ itself, irreversible changes will soon begin, which lead to degradation. Alas, the world standard for diagnosing brain death does not yet exist, so the fact that the criteria and methods of this procedure differ in different states is certainly alarming.
Do not substitute reality for metaphor
The logical continuation of the well-known metaphor that represents a living organism in the form of a machine with the most complicated mechanism will be the assumption that after death the work of everything gradually fades away: there is no “fuel” (oxygen and nutrients), the metabolism slows down and gradually all the “engines” stop work However, in biology, it is important not to replace reality with a beautiful metaphor or convenient model. That is why the collaboration of scientists under the guidance of the microbiologist Peter Noble during the working hypothesis: “Probably, the genes stop working after death” decided to set up an experiment to check what actually happens to the genes. Indeed, exploring death, you can learn quite a lot about life!
Genes on galleys
"Gene works" - the status of the DNA segment from which information is read using various cellular machines. At the same time, molecules are formed, which are called the common word “transcripts”. A transcript is a collection of all transcripts that are present in a sample. Currently, one of the main methods for measuring gene activity is the analysis of transcriptomes of various tissues. Unlike the genome, which is stable and the same in all cells of the body, the transcript can vary considerably depending on the environmental conditions, the state of the cell and its origin.
Life after death in the lab
To study empirically death, you need to kill animals. Such work requires the preliminary passage of many special commissions on bioethics. The experiment of Peter Noble’s team consisted of the following: the animals were killed at a time and then placed in a familiar environment. At the same time, both in the aquarium and in the air, circulation of water or air was maintained. In order to conduct further research on samples, several bodies were taken with a certain frequency and frozen in liquid nitrogen. Such a collection of "samples" was carried out within 48 hours from the moment of death of the mice and 96 hours from the moment of the death of the fish. As a result of the analysis of the so-called thanatatranscriptome (from the Greek “thanatos” - death), 1063 genes were anotable. The activity of most of them after death decreases sharply, but some of the DNA sites do not know anything about death and continue to work. Some of the examined genes remained active for 4 days after the death of the animal.
Postmortem results
Researchers emphasize: their data show not “residual activity”, but the independent work of genes after the death of an animal. In confirmation of this, they cite the data of quantitative analysis of transcripts. The change in the volume of molecules in tissues occurs in different ways. As a result of qualitative analysis, functional characteristics of individual groups of genes that work in the cells of a dead body (from the point of view of the processes in which they participate) were obtained: stress response, internal and adaptive immune response, inflammatory process, cell death, transport and regulatory processes, oncogenesis as well as embryonic development.
Death is stress
In both organisms, the peak of the work of these genes fell on the day after death. The researchers explain this as an attempt by the body to restore balance in the absence of resources. We are talking about such genes as the stress response, such as heat shock genes, hypoxia, and other types of reactions, such as oxidative stress.
Death is a struggle
Those who believe in life after death, realize that the human body from the mortal container for the soul becomes refined purgatory for various living organisms. Bacteria, worms, and then arthropods, perhaps even bigger animals, in general, everyone who does not disdain will become the life that fills the body of a large mammal after death. In this case, the fact that after the death of the genes of the immune response is activated is quite logical. Despite the fact that the empire of the human body is already dead, individual cells continue to exist and launch molecular machines into battle, activating the genes of the immune response and inflammation.
Death is when cells die
In the cell there is a well-established system of launching your own “death machine”. This is required in cases where it becomes clear that "something went wrong." Starting with the expression (generation of a transcript) of one of the genes, a cascade of proteins starts up, which leads to cell death. The process of programmed cell death is called apoptosis. It was not possible to establish any general patterns of the work of apoptotic genes in both types of organisms, but it was noted that they are actively working in both.
Death is vanity
It would seem, why, in the absence of a functioning organism, would it be necessary to transfer ions, proteins or signaling molecules from a cell to a cell? Why "fold" DNA segments? According to the observations, the majority of such genes in the corpses of fish ceased their work 24 hours after death, while the transport genes of the cadavers of mice continued to work for 2 days.
Death is oncogenesis
There are genes in the world's genetic databases that are listed as “oncogenes”. They get such a “label” if it has been noticed that malignant neoplasms develop during their work. The composition of these genes and the characteristics of work vary greatly in organisms.
Death is just the beginning
Perhaps the most unexpected finding in this experiment is the work of the genes that are responsible for the early stages of embryonic development. Surprisingly, after death, the genes that worked at the moment when the dead body was a fertilized egg or egg cell and just created the muscles or the nervous system are included. Scientists admit to the article that they are very surprised by the discovery of these genes, and offer two versions of the explanation of what is happening. On the one hand, maintaining the “silence” of these genes can be an active process, which ceases with the death of general regulatory systems. On the other hand, the physiological conditions of a dead organism can remotely resemble those under which embryonic development occurs.
In addition to the games of pundits and plans for immortality in the near future, there are two serious issues that are directly related to such research. First of all, it is organ transplantation from recently deceased donors. It is known that the risk of cancer increases with organ transplantation. The most common example is skin cancer (it is possible that oncogenesis is due precisely to the work of oncogenes in dead tissue). On the other hand, in the subsequent analysis, you can create a method for accurately determining the time of death based on the composition of the tanatotranscriptome.
So, dear friend, it turned out that even in ordinary mice and fish, after death, there are more than a thousand genes. Is this not a miracle? (Is this not motivation?)
Thanks to everyone who read us and was with us this year. And we have prepared a DNA test "under the Christmas tree." Just like in the best times of our life: you tell a short interesting fact about genes or genetics (however, not necessarily in text format), and you get a DNA test as a gift. Detailed rules - by reference .
Source: https://habr.com/ru/post/400413/
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