Electric eel reveals the secrets of evolution!

On the bottom of the Amazon River, a wiry fish called an electric eel lurks in the dark to eat unwary frogs or other small prey for lunch. When the prey approaches and swims alongside the eel, the strange creature releases two 600-volt electrical pulses, killing the unlucky creature. It's true that this high voltage hunting tactic is aesthetically amazing and special, but only a handful of fish species use electricity to hunt! It is interesting to know that even Charles Darwin thought about the electrical abilities, biological classification and geographical location of this creature in the book Theory of Evolution (Origin of Species) and acknowledged that the idea of the existence of this extraordinary organ and its repetition in the process of evolution It is truly amazing.

BingMag.com Electric eel reveals the secrets of evolution!

On the bottom of the Amazon River, a wiry fish called an electric eel lurks in the dark to eat unwary frogs or other small prey for lunch. When the prey approaches and swims alongside the eel, the strange creature releases two 600-volt electrical pulses, killing the unlucky creature. It's true that this high voltage hunting tactic is aesthetically amazing and special, but only a handful of fish species use electricity to hunt! It is interesting to know that even Charles Darwin thought about the electrical abilities, biological classification and geographical location of this creature in the book Theory of Evolution (Origin of Species) and acknowledged that the idea of the existence of this extraordinary organ and its repetition in the process of evolution It is truly amazing.

Meanwhile, some species are able to move in muddy waters and slowly, and when the prey is close to them, they release soft shocks with a weaker voltage and make the prey unconscious. Typically, when several species share unusual abilities, such as generating electricity, they are likely to be closely related. But the electric fish of the rivers of South America and Africa include six separate classes, and there are also three species of other marine and electric creatures. Therefore, understanding the process of evolution and mutation of these creatures has led scientists to further research on this creature!

How does the electric eel generate electricity?

Researchers have recently published an article in the journal "Science Advances" to help discover one of the most important evolutionary secrets in electric eels. Harold Zakon, a biologist at the University of Texas at Austin and one of the study's senior authors, admits that they were only following Darwin's procedure, as most biologists do. By collecting and piecing together genomic clues, this biologist and his colleagues show the presence of similar electrical organs in the ancestors of electric fish that were separated by approximately 120 million years of evolution and 1,600 miles of ocean. So it seems that there is more than one way to evolve an electric organ!

South American and African fishes use special electric organs that extend further along their bodies. In the body of these organisms, there are modified muscle cells called electrocytes, which are responsible for the distribution of sodium ions. When protein channels of sodium ions in the membrane of electrocytes open, a sudden flow of electrical signals is produced.

Electrocytes can be thought of as electrical organs of modified muscle or, in some cases, nerve tissue that conduct electrical discharges in order to Defense or mating helps in electric fish and eels!

In general, in other organisms that do not have electric organs, this current of signals flows through their muscles and flows within and between cells to cause muscle contraction. help in movements; But the presence of electrical organs in these fish helps to direct the flow of electrical signals to the outside of the body. In this regard, the strength of each electric shock depends on the number of active electrocytes at a moment. Most electric fish are only capable of firing a few currents at a time, but because the electric eel is equipped with an unusual number of electrical cells, it can release voltages powerful enough to kill small prey.

The presence of a large number of electric cells in the body of the electric eel allows this predator to kill the prey by releasing only one or two electric currents!

Evolution and defense system of the electric eel

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BingMag.com Electric eel reveals the secrets of evolution!

It was about 320 to 400 million years ago that the ancestors of all fish classified as bony fish died from an accident. Rare genetics survived and reproduced their entire genomes. Entire genome duplication is often fatal for vertebrates, but since these organisms have duplicated extra copies of everything in their genomes, this (whole genome duplication) has opened up previously unrealized genetic possibilities!

Genome duplication is the process by which additional copies of the entire genome are produced due to non-disjunction during meiotic division.

So for the more recent ancestors of the freshwater electric fish, which are also classified as bony fishes The genome duplication meant that they would have an extra copy of the gene that diffuses sodium ions. In fact, one copy of this gene takes over the same normal process in muscle cells (similar to humans and other organisms) and the second acquired mutation confers distinct electrical properties to electrocytes.

At the same time, one of What is very important in this matter is that initially, the second version of the gene (acquired mutation) had to be deactivated in the muscle cells. Because this issue is important because emerging electrocytic capabilities can interfere with animal movement! So when Zaccone and his colleagues looked at how the electric fish turned off the gene, they were surprised to find that different species of fish did it in different ways. African, the gene for diffusion of sodium ions was operational but, like a lock without a key, could not be activated without helper molecules (not made by muscle tissue!). On the other hand, in most of the South American fishes, the part that diffuses sodium ions was not present in the muscles, and the sodium diffusion gene was largely inactive. This is because an essential control element that specifically enhances the expression of the sodium diffusion gene in muscle was missing.

In some exotic South American fish species, this gene is still operational in muscle and Young fish has been temporarily disabled. But when a different set of genes take over control of the sodium channels in the electrical organ of the adult fish, the gene is reactivated. Therefore, according to the "convergent evolution" discussion, different species of fishes have independently moved towards the strategy of modifying their muscle tissue to create electrical organs, and they have even done this by making sodium diffusers selectively in different tissues. But there have been differences in how these players are regulated and activated.

Evolution or convergent evolution is a process by which living organisms that are not closely related to each other independently acquire similar traits! In other words, when the same evolutionary pressures are applied to two different biological species, the same characteristics will arise to respond to these pressures.

Johann Eberhart, a molecular biologist at the University of Texas and one of the people present in this new study, explains that in most cases when scientists talk about convergent evolution, they are basically referring to similar and independent traits in organisms that are not closely related. But this study took a completely different approach, and I think the results are surprising.

While other bony fish have lost a copy of a specific gene for sending signals between nerves and muscles, some species Electric fish saved them. Therefore, with these key genes that put the electric organs under voluntary and direct control of the animal, the electric eel can develop its own strong signals. It is responsible for generating high-voltage signals in the electric eel!

Also during this study, Zaccone and his colleagues were surprised by the potential importance of the control region they found in sodium ion diffusion genes! Because this section seems to specify exactly which tissues express the protein. It is interesting to know that the same control area exists in the distribution of sodium ions in humans and other vertebrates. It is therefore possible that mutations affect the sodium diffusion activity in our cells and cause various problems such as myotonic dystrophy (muscle dysfunction) or contribute to the exacerbation of such diseases! It should be noted that the new research presents and examines only a few examples of convergent and divergent evolution in electric fish!

In the end, we must emphasize that for Zakun and his colleagues, these convergent solutions are intended to address It is very useful for a fundamental puzzle in biology, which is if we could turn back the course of evolution, would everything work the same way?

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