Notícia (Índia)

Completed first sequencing of Brazilian pit viper – revealing the origin of its toxic toxin

Publicado em 16 agosto 2021

In the article published in PNAS Researchers at the Butantan Institute describe the genome of Bothrops jararaca and suggest the origin of the genes responsible for toxins in venoms.

A group led by researchers at the Butantan Institute and funded by the São Paulo Research Foundation — FAPESP has completed the first sequence of the Brazilian snake genome.This study is reported in an article published in the journal PNAS..Nine genes encoding toxins produced by the beetle Bothrops jarara Probably derived from genes that had different functions in ancestral species.

“In sequencing the snake genome, we identified 12 toxins in Hararaka that allow the toxin gene to be compared to genes at the same location in the genome of other animals, such as non-toxic snakes, lizards, and amphibians. Nine of the genes were found to be very similar to those occupying the same position in Haralaka. DNA Of these other species. Inacio Junqueira de Azevedo, a researcher at the Butantan Institute and the last author of the article, said:

Azevedo is a Principal Investigator at the Toxin, Immune Response and Cell Signaling Research Center (CeTICS), one of the FAPESP-funded Research, Innovation and Dissemination Centers (RIDCs).

“These genes had physiological functions in the common ancestor of all these species. At some point, they probably began to play a role similar to the toxin gene, or were chosen for this pathway and were originally Lost function. Our research finds elements that help scientists understand the mechanisms that led to the evolution of toxins and the mobilization of specific genes to perform this new function in toxin production. “It was,” said Diego Dantas Almeida, the first author of the article. This study was conducted during a PhD study supported by FAPESP.

Sequencing also showed that the two genes encoding important toxins probably came from duplication. In any organism, genes usually evolve more freely, and when a copy performs its original function, it performs a variety of functions.

In Bothrops jarara, the copy must have undergone selective pressure to produce two families of toxins, the snake venom metalloproteinase (SVMP) and the phospholipase A2 (PLA2), which make up the majority of the action of the venom. Most of the genes encoding this snake toxin were already thought to have originated this way. It was not possible to determine the origin of only one of the 12 gene families encoding the toxin.

“We were able to show that these two families have non-toxic” ancestral “genes. They are still present in DNA, alongside toxin genes. The ancestral genes have completely disappeared from other families. They are probably converted to toxin genes, “said Vincent Louis Viala, co-author of the article and a former recipient of postdoctoral fellows from FAPESP.

Research effort

The Butantan Institute group began sequencing the snake’s genome in 2013. B.jararaca is the cause of most snakebite accidents in Brazil and is one of the most studied snakes for this reason. Sequencing provided basic information about the origin of the previously missing poison.

In addition to increasing knowledge of the genes of an organism, sequencing its genome assembles them in the correct order. This is one of the most complex parts of the task, as sequence processing produces large amounts of data and must be processed using computational tools.

In recent years, after combining several methods, with the help of researchers at The Ohio State University in the United States, the group has succeeded in fully assembling the genome.The complete genome sequence Available Anyone who wants to study it online.

The project has produced answers to some other important questions. Analysis of specific toxin genes by Japanese researchers in 2009 Protobothrops flavoviridisBelonging to the same family as Bothrops jarara (Viperidae), suggested that the gene encoding the toxin VEGF-F, which is also present in Brazilian snakes, is probably due to duplication of the gene VEGF-A. The Brazilian group has shown that it is likely to come from another gene family known as “PGF-like” in the scientific literature.

This group also provides more evidence that the bradykinin-enhancing peptide (BPP), which is the basis of the antihypertensive drug captopril, is derived from the gene CNP, which probably encodes the type C natriuretic peptide present in other vertebrates, including humans. I collected it.

“This study shows that in order to get a good understanding of the origin and evolution of a gene, we need to identify where the gene is inserted,” Azevedo said.

Researchers are currently working on more sophisticated versions of the Bothrops jarara genome and other venomous snake genomes, hoping to find new toxins and link them to proteins related to the physiology of other organisms. is.

See also: Tracking snake toxin mobilization and evolution using the evolutionary context provided by Bothrops jarara Diego Dantas Almeida, Vincent Luis Biara, Pedro Gabriel Nachtigal, Michael Blow, H. Lyle Gibbs, Solange Maria de Toledo Serrano, Ana Maria Moura da Silva, Paul Lee Ho, Milton Yutaka Nishiyama Jr., Inacio LM Junkeira-de-Azevedo, May 18, 2021 Minutes of the National Academy of Sciences..
DOI: 10.1073 / pnas.2015159118

The study also includes a thematic project under the auspices of the FAPESP Research Program on Biodiversity characterization, Conservation, Restoration and Sustainable Use (BIOTA-FAPESP), and a regular research grant awarded to Azebed. Funded through money. Completed first sequencing of Brazilian pit viper – revealing the origin of its toxic toxin