Scientists have described how the snake lost limbs in the course of evolution

Ученые рассказали, как змеи потеряли конечности в ходе эволюции

The researchers compared the genome of the snakes with the genes of reptiles, which have legs.

Scientists from the Institute of molecular cell biology and the max Planck Institute analyzed the genome of snakes and other vertebrates, and determined the elements that control the formation of limbs. As reported by the online edition of the Chronicle.info with reference to zn.ua the researchers also analyzed the degradation of the eye in some of the underground animals.

“Our work consisted of studying the genomes of several vertebrate species, including identification of genomic regions that have changed just the snakes or underground mammals, while remaining unchanged in other species that have not lost limbs or have normal eyes”, – says the head of the research group Juliana Gusson rossito.

According to scientists, the mammals with degraded visual system, isolated from the genomes of certain genes, usually those associated with the formation of the lens and photoreceptor cells in the eyes. Most likely, this process was gradual, and, in the end, these genes completely lost the ability to encode proteins. However, snakes have not lost the genes that are associated with the formation of the limbs. Therefore, the researchers suggested that it is not in the genes and elements that control their expression.

Gene expression – whether “active” gene or not depends on regulatory elements that are located outside the gene. They allow or block the information within the gene, which is transcribed into RNA and then transferred to generate the protein. This process is controlled by CIS-regulatory elements (CRE) sequences of nucleotides in DNA located near the genes they regulate. These CRE can significantly change the functionality of the genome with the genes that they block or activate.

In the study, researchers compared the genome of the snakes with the genes of reptiles and vertebrates that have limbs. They also emphasize that “genomic sequence for reptiles with well developed limbs small,” so they alone and for the first time sequenced the genome of the Argentine black and white tag. Then, using this gene as an example, scientists have examined the genomes and of several other types: two snakes (boa and Python), the other three reptiles, three birds, alligator, three turtles, 14 mammals and fishes of order Alcantaras.

As a result, they were able to identify a set of CRE, the mutation of which could lead to the disappearance of the limbs of these reptiles. However, CRE was found is just one of the regulatory elements for one of the several genes that control the formation of limbs. In their work, scientists have greatly expanded this set by showing that some other elements responsible for the regulation of many genes, mutated snakes.

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