There are some natural phenomena that we see daily and take for granted. So, the sun sends us its heat and light, and there’s nothing faster than it, and water and oxygen are considered essential requirements of multicellular organisms. Today, however, some of these postulates, it seems necessary to reconsider, for example, in the relationship between oxygen and survival of organisms.
Why are we talking about this? Just because this year scientists have discovered that the gelatinous parasite does not have mitochondrial DNA. This is the first multi-celled organism that lacks a genome of mitochondria. This means that the parasite is not breathing. In fact, this body is living a completely oxygen-free life.
This discovery not only changes our understanding of life on planet Earth, but also can have important implications for searches for extraterrestrial life. Now, scientists do not need to confirm the availability of oxygen on the planet, so we believe in the possibility of life on it, and thus her quest will change drastically.
The history of mitochondria. The breathing of living organisms
We need to go back to what we studied in high school. When we talk about this phenomenon as breathing, we remember the process of inhaling oxygen and release carbon dioxide through the lungs. In fact, all different. In biology this process is called gas exchange, that is exchange of gases between the organism and the external environment. The process of breathing has an entirely different meaning. Gas exchange is a physical process and respiration — chemical.
Respiration or cellular respiration is the set of reactions and processes that occur in cells of living organisms to produce energy by converting nutrients into oxygen molecules. In other words, respiration is the process of oxidation of the compounds, which we eat to get the energy needed for formation of body cells.
Living organisms have developed the ability to absorb oxygen, i.e. breathing, is approximately 1.45 billion years ago. At that time, the microorganism, similar to bacteria, but larger, called area, swallowed a handful of smaller bacteria. Somehow the new process was beneficial to both parties, and they stayed together, representing absolute harmony.
This symbiotic relationship has led to co-evolution of two organisms, and eventually the bacteria became organelles called mitochondria. This is the most popular among scientists hypothesis proposes that mitochondria were originally prokaryotic cells, capable of the oxidative mechanisms that were not possible during the eukaryotic cell. This theory is supported by the fact that mitochondria possess many of the properties of bacteria.
Every cell in the human body, except red blood cells, contains a large number of mitochondria that are necessary for the respiration process.
How the process of respiration?
Breathing occurs by converting chemical energy in molecules of oxygen and nutrients in the so-called adenosine triphosphate (ATP). This substance is a compound, which can be compared with the “energy currency”. In other words, these compounds are the source of energy that is consumed in various energy consuming processes.
The process of energy production takes place in the form of a chain of biochemical reactions in which large molecules are splitting into smaller ones and energy is released that is. Most of these reactions are the processes of oxidation and reduction.
Although cellular respiration technically resembles a combustion reaction is found in nature, this is clearly not the same. The breathing process — the interaction within the cells, taking place by the slow, controlled release of energy, and this energy is not released directly, but are stored in the energy currency of cells (ATP). Because cellular respiration takes place with the obligatory participation of oxygen, scientists call it aerobic respiration or aerobic metabolism.
First multi-cellular organism that does not need oxygen to survive!
We also know that there are mods that allow some organisms normally exist in low oxygen or hypoxia. Some single-celled organisms developed mitochondrial organelles for anaerobic metabolism (i.e. without participation of oxygen). However, the ability of multicellular organisms to breathe exclusively anaerobic way has been a subject of controversy in scientific circles.
The debate about the existence of such organisms continued up until a group of researchers from tel Aviv University decided to study one of the most common parasites present in salmon, called Henneguya salminicola.
This organism belongs to the group of cnidarians, or flowing down. To it among other things includes corals, jellyfish and anemones. These parasites are in the fish unsightly cysts, but they are not harmful. They exist in the salmon during its lifecycle without any problems.
In the body of his master, this tiny parasite can survive in such a hypoxic environment. However, it is difficult to know exactly how it happens, not having studied the DNA of an organism, and engaged Israeli researchers. They used deep sequencing methods and fluorescent microscopy for a more thorough study of this parasite and found that he had lost the mitochondrial genome. In other words, his DNA is devoid of the gene that is responsible for the synthesis of mitochondria. In addition, the researchers found that he also lost the ability to breathe air and almost all of the genes required to participate in the processes of transcription and replication of mitochondria.
As unicellular organisms, this parasite has evolved mitochondrial organelles, but they are also unusual in their inner membrane has folds that are not normally visible. Thus, as evidenced by the results of the study finally found a multicellular organism that needs no oxygen to survive.
Why can’t he breathe?
How does this body exist? The answer to this question is shrouded in mystery. Perhaps the parasite is able to extract ATP from their infected host, but it is still not completely defined. Nevertheless, the loss of the parasite mitochondrion is fully consistent with the General tendency of these organisms to genetic simplification. Over the years, they are in fact evolved from their predecessors in a much more simple parasites that we can see today.
Henneguya salminicola has lost much of the original genome, his cousin Medusa, but in a strange way kept a complex structure similar to the structure of the cells of jellyfish. This discovery could help fisheries to adapt their strategies to combat the parasite. Although it is harmless to people, hardly anyone wants to buy salmon, which is infested with weird little gelatinous organisms.
To understand life and to find living organisms in space
Perhaps the real significance of this discovery is to help us understand how life works. This discovery confirms that adaptation to an anaerobic environment is not a unique ability of unicellular organisms, but is also among multicellular parasites. Thus, a unique parasite Henneguya salminicola gives you the opportunity to study the evolutionary transition from aerobic respiration to anaerobic metabolism exclusively.
Thus, scientists can change their ideas about the forms of life that they are looking for outside of our planet. Now no need to look for oxygen on the surface of a particular planet, to predict the presence of life on or under the ground. Perhaps there are complex life forms that do not rely on oxygen for energy.