Insecticides play a central role in combating the global effects of malaria and other diseases, which are prevalent in mosquitoes, which kill an estimated 750,000 people each year. These insect-specific chemicals, which cost more than $ 100 million to develop and market, are also important in controlling crop damage from insects that pose food security challenges.
However, in recent decades, many insects have been genetically adapted to be less sensitive to the efficacy of pesticides.In Africa, it lasts long InsecticideTreated mosquito nets and indoor sprays were the primary weapons in the fight against malaria, causing many types of mosquitoes throughout the continent. Insecticide resistance It reduces the effectiveness of these important interventions. In certain areas, climate change is expected to exacerbate these problems.
Biologists at the University of California, San Diego have developed a method for reversing pesticide resistance using CRISPR / Cas9 technology.As explained in Nature Communications, Researchers Bhagyashree Kaduskar, Raja Kushwah, and Professor Ethan Bier of the Tata Institute for Genetics and Society (TIGS) and their colleagues used gene editing tools to make fruit fly pesticide resistance genes susceptible to normal pesticides. I replaced it with a form. This can significantly reduce the amount of pesticide used.
Bier, a senior professor of cell developmental biology at the University of California, San Diego, Department of Biological Sciences, said: The author of the paper.
Researchers used a modified gene drive, a technique that uses CRISPR / Cas9 to cleave the genome at a target site and spread a specific gene throughout the population. When one parent transmits the genetic element to the offspring, the Cas9 protein cuts the chromosome from the other parent at the corresponding site and the genetic information is copied to that location so that all offspring inherit the genetic trait. increase. The new gene drive includes an add-on previously designed by Bier and his colleagues, which includes simple genetic mutations (also known as alleles) by cutting out and replacing unwanted genetic mutations (such as pesticide resistance). It is biasing the inheritance of (called). It is a preferred variant (eg, pesticide susceptibility).
In a new study, researchers adopted this “allelic drive” strategy to restore genetic susceptibility to pesticides, similar to wild insects before developing resistance. They focused on an insect protein known as voltage-gated sodium channel (VGSC), which is the target of a widely used class of pesticides. Resistance to these pesticides is often referred to as knockdown resistance, or “kdr,“The result of the mutation vgsc A gene that no longer allows pesticides to bind to its VGSC protein target.The author replaced the resistant one kdr Mutations with normal natural counterparts that are susceptible to pesticides.
Start with a population of 83% kdr (Resistance) Alleles and 17% normal alleles (insecticide susceptibility), allele-driven systems reversed their proportions to 13% resistance and 87% wild type in 10 generations. Bier also states that adaptations that confer pesticide resistance come with evolutionary costs, making those insects less likely to fit into Darwin’s meaning. Therefore, he says, combining gene drives with the selective benefits of more adapted wild-type gene variants results in a highly efficient and collaborative system.
Similar allele-driven systems may be developed in other insects, including mosquitoes. This proof of principle adds a new way to the pest and vector control toolbox as it can be used in combination with pesticide-based or other strategies to improve parasite reduction measures to control the spread of malaria. ..
“Through these allelic replacement strategies, we should be able to achieve the same degree of pest control with much less pesticide application,” Bier said. “It should also be possible to design a self-excluding version of the allele drive programmed to act only temporarily within the population to increase the relative frequency of the allele of interest and then disappear. Such locally acting allelic drives can be reapplied and increased as needed. Abundance of naturally occurring favorable traits. The final endpoint is GMO in the environment. It’s not left. “
“The exciting possibility is to use allelic drives to introduce a new version of VGSC that is more sensitive to pesticides than wild-type VGSC,” said study co-author Craig Montell (UC Santa Barbara). ) Suggested. “This has the potential to introduce lower levels of pesticides into the environment to control pests and disease vectors.”
Bhagyashree Kaduskar et al, Allele-driven reversal of insecticide resistance in Drosophila melanogaster, Nature Communications (2022). DOI: 10.1038 / s41467-021-27654-1
University of California, San Diego
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