Amazing new research: We’re more like primrose fish than we once believed

Lungs and organs have traditionally been thought to be the main mechanisms that came with the vertebra movement from water to land. But of course, the genetic basis of air movement and limb movement was already established in the ancestor of our fish 50 million years earlier. This is, according to recent genome mapping of primitive fish conducted by the University of Copenhagen, among others. The new study will change our understanding of a major milestone in our own evolutionary history.

Nothing new about humans and all other backbones has grown from fish. The common understanding was that some fish migrated to land around 370 million years ago as primitive, lizard-like animals called tetrapods. According to this understanding, our fish ancestors descended from water to land by changing their wings to limbs and breathing underwater into the breath of the air.

However, organs and lungs are not the inventions that once emerged as new as they once believed. Our common fish ancestor that lived 50 million years before the tetrapod first landed carried the genetic codes for limb-like shapes and airborne breath needed to land. These genetic codes are still present in humans and a group of primitive fishes.

This was confirmed by a recent genomic study conducted by the University of Copenhagen and their partners. The new research reports that the evolution of these ancestral genetic codes may have contributed to the water-to-land vertebrate movement, altering the traditional view of series and timeline of the evolutionary giant leap. seo. The study was published in the scientific journal Cell.

“The movement of water to land is a major milestone in our history of evolution. The way to understand how this movement happened is to reveal when and how the lungs and organs came into being. We are now able to show that the genetic basis underlying these biologics. The activities took place much earlier before the first animals landed, “said the chief. professor and lead author Guojie Zhang, of the Villum Center for Biodiversity Genomics, at the Department of Biology at the University of Copenhagen.

A group of old living fish may hold the key to explain how the tetrapod may eventually grow and breathe air. The fish group includes the bichir that lives in shallow freshwater habitats in Africa. These fish differ from most other bony fish by carrying traces that our early ancestors may have had 420 million years ago. And the same traits are present as an example of people. Through a genomic sequence the researchers found that the genes required for lung and limb development have already appeared in these primary species.

Using a pectoral fine with locomotor action as a boundary, the bichir can move around land in a manner similar to the tetrapod. Researchers have believed for several years that pectoral fins in bichir represent the feathers of our early fish ancestors.

Mapping of the new genome shows that the joint connecting the metapterygium bone is socalled with the radial bones in the pectoral gland in the bichir homologous to synovial joints in humans – the joints that are ‘connecting the upper bones of the arm and forearm. The DNA sequence that controls the formation of our synovial joints was already present in the common ancestors of bone marrow and is still present in these primary fish and in terrestrial spines. At some point, this DNA sequence and its synovial component were lost in all common bony fish – the socalled teleosts.

“This genetic code and its component allow our bones to move freely, which explains why the bichir can move around land,” says Guojie Zhang.

In addition, the bichir has a pair of lungs and a few other prime fish that are anatomically similar to ours. The new study reveals that the lungs both in bichir and alligator us also function in the same way and express the same set of genes as human lungs.

At the same time, the study shows that the lung and bladder floating tissue of most extinct fish is very similar in gene expression, confirming that they are homologous organs as before. Darwin expects. But while Darwin suggested that swimming salmon would turn into lungs, the study suggests that swimming hollows are more likely to come from the lungs. The research shows that our early ancestors had fish lung primary activity. Through evolution, one branch of a fish retained the functions of the lungs that are better suited to breathing air and eventually the evolution of tetrapods followed. The other branch of fishing changed the structure of the lungs and came up with swimming braces, following the evolution of teleosts. The swimming flags allow these fish to maintain vitality and see weight, and thus better survive underwater.

“The study clarifies where our organs came from and how their functions are coded in the genome. Therefore, some of the lung-related activities did not occur. and the organs are present at the time of the movement of water to land, but are coded by some ancient gene control mechanisms that were already present in our fish ancestors long before they came ashore. it is interesting that these genetic codes are still present in these ‘living fossil’ fish, which allows us to trace the root of these genes, ”concludes Guojie Zhang.

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Fish and primates also share a common and essential function in the cardio-respiratory system: The conus arteriosus, a structure in the right ventricle of our heart that can allow the heart to deliver oxygen properly. effective for the whole body, and which is also found in the bichir. However, most bony fish have lost this structure. The researchers found a genetic element that appears to control the development of the conus arteriosus. Transgenic experiments with mice showed that, when researchers removed this genetic element, the mutated mice died as a result of thinner, smaller right ventricles, leading to congenital heart defects and dangerous heart activity.

• Most of the existing fish species belong to the sting, a subclass of bony fish. These are usually fish with gills, wings and a swimming pulse.
• The terrestrial body of vertebrates is called a tetrapod. The tetrapod encompasses all the vertebrates derived from the first animals that were transformed into life on land by developing four organs and lungs, ie, mammals, birds, reptiles and amphibians .
• The researchers’ theory is that the ability to breathe the air in these primeval fish allowed them to survive a second extinction about 375-360 million years ago. At that time, lack of oxygen in the Earth’s oceans caused most species to be extinct. The lungs allowed some of the fish to survive on land.
• The study was published in the scientific journal Cell. Get to the research article here. The research team also contributed to another paper that described the genome for another primary fish, the lung. The genome is the most coded vertebrate genome to date. This paper was published in Cell At the same time.
• The research is supported by the Villum Foundation, among others.