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The lost "junk" DNA is in the human genome. Genes only occupy 2% of the sequence, and the rest is made up of genetic material called non-coding DNA. Scientists have tried to solve this mystery for many years: Why is there such a large amount of this genetic material in the genome? Now, a new study has brought unexpected new findings: the vast majority of non-coding DNA may indeed not be needed for complex life. The research was published in the journal Nature on May 12. The clue is in the genome of the carnivorous algae plant-Utricularia gibba. The Genus Cypripedium is the smallest genome to date, a complex, multicellular plant genome that has been sequenced. Sequencing staff said that 97% of the genome of the bladderwort was found to be composed of genes, and some small DNA fragments control these genes. Scientists say that it seems that this plant has been busy removing non-coding "junk" DNA from genetic material for generations. This may be used to explain junk DNA-rich species such as bladderworts, corn and tobacco, as well as the differences between humans. Victor Albert, one of the leaders of the study and a professor of biological sciences at the State University of New York at Buffalo, said: "An important part of the story is that only 3% of the genetic material of the bladderwort plant is so-called 'junk' DNA. Somehow, This plant removes most of the DNA that makes up the genome of the plant. In other words, you can get an excellent multicellular plant with a large number of different cells, organs, tissue types, and flowers, and it can be free of junk DNA. This garbage is not needed. "Non-coding DNA is DNA that does not encode any protein. It includes moving elements called jumping genes that have the ability to copy (or cut) and paste themselves into new locations in the genome. Scientists have devoted countless hours to answer the doubts that such a large amount of non-coding DNA exists. A series of recent papers from the international research project ENCODE began to provide us with an explanation: the vast majority (about 80%) of non-coding DNA seems to play an important role in many biochemical functions, such as regulating and promoting DNA transcription into RNA. However, Albert, Luis Herrera-Estrella and colleagues believe that it is impossible for organisms to accumulate only large amounts of genetic waste for profit. On the contrary, they believe that some species may have an internal mechanism that prefers to delete large amounts of non-coding DNA; while other species have an internal mechanism that favors inserting and replicating DNA. These biases are not due to one behavior being more beneficial than the other, but both inherent ways work, and all living things just use them to varying degrees. The position of the organism on this floating slide rule depends in part on the degree to which Darwin's natural selection pressure can counter or increase these inherent biases. The new Cypripedium genome shows that having a bunch of non-coding DNA is not critical for complex life. Utricularia is an abnormally complex plant. It lives in aquatic environments such as freshwater wetlands, forming corresponding highly specialized hunting methods. In order to prey on prey, the plant has to evacuate the water in the bladder, making it a vacuum, so that it can inhale and capture living things. The researchers said that the Cypripedium blazeiflora genome has about 80 million DNA base pairs, which is obvious compared to the 490 million and 780 million base pairs of large genomes of the phylum Helicopsis inbreds and tomatoes, respectively. It is much smaller, and the deletion of non-coding DNA seems to cause most of these size deviations. However, Cypripedium has 28,500 genes, the number of which is comparable to grapes and tomatoes. Even more surprising is that the genome of Utricularia is small, but since its evolutionary lineage was separated from tomatoes, three rounds of whole-genome duplications (WGDs) have occurred. This indicates that in three different periods of evolution, the genome of the bladderwort plant has doubled, and the progeny obtained two complete copies of the entire genome of the species. "This amazingly rich history of replication, combined with the fact that the current genome of the bladderwort plant is small, further shows that the plant has been deleting a lot of unnecessary DNA, while retaining a set of functional genes similar to other plant species, "Herrera-Estrella said.
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