(ORDO NEWS) — Scientists at the University of California, Santa Cruz have uncovered an ancient genetic mystery about the origin of introns.
Introns are pieces of DNA that do not directly code for proteins. They are not present in mature RNA because they are removed during the primary transcript.
These sites are found in all eukaryotic organisms, which include animals, plants and fungi, but are absent in bacteria. Even in the genome of closely related species, the number of introns can differ significantly.
For a long time, many researchers could not identify the main mechanism for the appearance of introns. To determine it, the authors studied the genomes of 3325 eukaryotic species.
They were interested in how common in introns are introners – mobile genetic elements related to transposons.
(TES) and generating introns. This made it possible to study the frequency and scale of intron increase in all eukaryotic lines.
They found a total of 27,563 introners in the genomes of 175 species, or 5.2 percent of the samples studied. Scientists believe that this is evidence of the involvement of introners in the origin of introns, since the first have been identified in all species from animals to single-celled organisms, whose common ancestor lived more than 1.7 billion years ago.
In addition, the results showed that introners are 6.5 times more common in marine organisms than in terrestrial species.
The researchers believe this is likely due to horizontal gene transfer, in which genes are passed from one species to another, as opposed to vertical transfer, where genes are passed from parent to offspring.
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