A newly discovered huge virus makes the origins of life even more annoying

For decades, viruses were defined as being located between living things and non-living things. The characteristics of viruses are "small in size" "small in genome" "have a high dependence on parasitizing cells to duplicate themselves" "Although it is active, it is clearly different from other organisms It is distinguished from different things ". However, in 2003 the researchers discovered huge viruses that could be mistaken for bacteria, so the characteristics of the virus, so to speak, "virus definitions" are about to collapse.

New Giant Viruses Further Blur the Definition of Life | Quanta Magazine
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There are several kinds of huge things among viruses. In addition, some of the huge viruses have more than 1000 genes, some of which have more than 2500 genes. In addition, ordinary viruses have far fewer genes than large viruses, some of which have only four genes. Among the genes of viruses,mRNAReaction for synthesizing proteins based on information of "translationThere are also ones related to FranceAix-Marseilles UniversityChantal Abergel, an evolutionary biologist, says "A huge virus is as complex as an organism."

In a study on a giant virus just published on Nature Communications, "Two new huge amoeba infectious viruses"Has been discovered and is named" Tupanviruses "(Tsuban virus). Tsunanovirus is a strange-shaped virus with a long tail and has a set of the most complete translation-related genes including 20 enzymes that determine the specificity of the genetic code . There is also a thing lacking in this Tun virus, it seems to be a ribosomal gene.

The virus that carries translation - related genes is not only Tsukuba virus. For example, in 2017, researchers added "like Tsuban virus to a wide range of translation-related genes"KlausovirusWe publish the analysis results on a giant virus called "virus". "Virus seems to be extensively mixed in the translation domain and it is worth noting" Although not directly related to either study, it is famous as a virologist at the Max-Planck Institute Mr. Matthews Fischer.


The latest research results on these large viruses tell us about when and how the virus evolved,It is causing controversy among researchers. Although the process of the evolution of all viruses is not known in detail, "Tsuban virus" and "Kuruso new virus" are different virus groups but have translation-related genes, so that their origins are extremely There is a close possibility. However, "Since the virus knows that the gene has been recombined and exchanging genes many times during the course of evolution, it is difficult to specify precisely where it originated from," said Fisher .

A huge virus is useful not only as an example of diversity but also to further explain how the virus works and evolving. Both large viruses such as Tsunamura virus and Kuriso New virus are obscure origins and evolutionary pathways at the time of article creation,Horizontal propagation of genesYaGene duplicationIt is thought that it has gotten huge from a small virus over a period of over two billion years, while adding genes via a process such as. Also, Mr. Fischer insists that "even before losing unnecessary genes, it may have been an autonomous organism."

Some of the genes of a huge virus are related to those found in cellular organisms such as bacteria, fungi and eukaryotes. In addition, 30% of the genome of Tsunovirus is the same as that of cellular organisms, and in the case of other viruses it has less genomes than cellular organisms in a smaller proportion.

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Mr. Abergel said, "I think that the virus already has a large-scale and complex system," and that the origin of life originated from the evolution of the original cells using different survival strategies It is. It became an ancestor of these huge viruses because the ancestor of the cell having the complete translation function became an organism and the original cell which was defeated by this evolutionary flow became "to be parasitized on the cell". Then I guess. Therefore, Abergel wrote that Tsunanovirus and other large viruses have a lot of translation-related genes.

So far, Tsunanova plays a role like a piece of a puzzle to clarify the formation of a huge virus. Researchers analyze translation-related genes in order to understand the evolution of translation ability more deeply, "Which gene is active?" "What role does the role play?" " Is it indispensable to do? "And so on. Christophe Deg, a graduate student at the University of British Columbia, said that the gap between cellular organisms and viruses is filling up, and new research findings on Tupan virus, Closo new virus, etc. are great for biology It is supposed to be knowledge.