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    Home > Biochemistry News > Biotechnology News > Uk Oxitec's plan to develop the genetically modified Aedes aegypti mosquito OX513A, "mosquito-control" has sparked controversy.

    Uk Oxitec's plan to develop the genetically modified Aedes aegypti mosquito OX513A, "mosquito-control" has sparked controversy.

    • Last Update: 2020-08-05
    • Source: Internet
    • Author: User
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    Since 2013, tens of millions of genetically modified mosquitoes have been sent to the Brazilian city of Jacobina, where they interbreed with wild mosquitoes and become infertile, significantly reducing the number of wild Aedes aegypti mosquitoes.
    However, a recent study published in Scientific Reports suggests that genes derived from genetically modified mosquitoes have been detected in local mosquito populations, suggesting that they and offspring of wild mosquitoes can also transmit genes.
    study speculates that the new "hybrid" mosquito may be more viable and could accelerate the spread of the virus in disguise.
    this view has also been questioned and opposed by bio-companies and some experts.
    Aedes aegypti is the largest mosquito species in the mosquito family, with nearly 1,000 different mosquito species, known as the "Flower Mosquito" (The Aedes aegypti mosquito), and the Aedes aegypti mosquito, which poses the greatest threat to humans.
    Aedes aegypti mosquitoes are the main vectors for a variety of deadly infectious diseases, carrying viruses that can cause yellow fever, dengue fever, Zika and other diseases.
    Aedes aegypti mosquito not only endangers human health, but also causes huge economic losses to the world.
    , Brazil and other countries are suffering.
    Because there are so few effective vaccines and drugs for mosquito-borne infectious diseases, scientists are inclined to cut off the spread of these infectious diseases by finding ways to control or eliminate mosquitoes that carry the virus.
    traditional methods are mainly to use insecticides to kill mosquitoes, but given its vulnerability to mosquito resistance, but also to the ecological environment is more destructive.
    now, scientists are actively seeking more effective solutions, and genetic modification is one of the most attractive new methods.
    more than a decade, Oxitec, a British biotech company, has been testing genetically modified mosquitoes.
    their strategy is to implant a lethal gene in the non-bite male Aedes aegypti mosquito, which, when the wild female mosquito mates, is passed on to the next generation, resulting in poor survival and "infertility" and significantly reducing the mosquito population.
    Oxitec has successfully developed the ideal genetically modified Aedes aegypti mosquito, codenamed OX513A.
    they first interbred the Aedes aegypti mosquitoes, which are of Cuban and Mexican descent, and then implanted two genes into the hybrids -- one that kills offspring and the other that produces fluorescent proteins for easy tracking.
    in laboratory conditions, only about 3 percent of offspring survive to adulthood after OX513A mating with wild type, and Oxitec believes that the few remaining survivors are not fertile.
    prospects seem bright.
    , the Brazilian government paid for OX513A to control the local mosquito and dengue fever.
    since 2013, Oxitec has been delivering about 450,000 OX513A male mosquitoes a week to the city of Yakobina, in the eastern Brazilian state of Bahea, for 27 months.
    The total number of wild mosquitoes in the area has fallen by 90 percent, according to Oxitec.
    unexpected gene transfer, according to Oxitec's perfect assumption, ox513A and local wild female mosquitoes mate with very low survival rates and are unable to have fertility.
    , however, is that really the case? Jeffrey Powell, an evolutionary biologist at Yale University, led his team in an independent investigation.
    in the 6th, 12th and 27th months after the start of the project, they took three samples and genotyped Aedes aegypti larvae at various locations in Jacobina, the last of which was a continuous sample for three months.
    analysis is a far cry from oxitec's report, in which the team found that the genomes of local mosquitoes changed significantly from the original, with about 10 to 60 percent of the individuals in the sample having genes from OX513A.
    this means that ox513A and the offspring of wild female mosquitoes are not only fertile, but also produce a number of "three-nation hybrids" in Brazil, Cuba and Mexico.
    and according to Oxitec's original description, hybrid offspring should be infertile and die quickly, so the ox513A gene should not be passed on.
    that is, this should not have happened.
    Powell is concerned about the phenomenon, speculating that the new mosquitoes may be more powerful than their parents.
    team tested the spread rate of the new variant strain of dengue and Zika virus, but found no significant difference.
    However, the researchers believe that these new variants may have different ability to transmit other viruses in the wild, or that gene infiltration of OX513A may increase resistance to insecticides in new variants.
    Powell stressed: "While the new variants do not present any known health risks, the unknown results are the most worrying."
    ", "It is important to note that, late in the project, the genetic penetration of OX513A was significantly reduced in samples collected by the Aedes aegypti mosquito collected by the research team."
    other studies have shown that the male mosquito in the early stages of the local Aedes aegypti mosquito played a huge inhibitory effect, but somehow, 18 months later, the inhibition effect greatly weakened, the number of Aedes aegypti mosquito gradually returned to the original level.
    Powell et al. speculate that the female mosquito of Yakobina may have developed a "mating bias", in which females are reluctant to mate with males with weak reproductive capacity, and that these genetically modified mosquitoes may be among them.
    rebutts and questions Powell et al.'s paper was strongly rebutted by Oxitec after it was published on September 10th in Scientific Reports. A spokesman for
    said Powell's team's research contained "a number of false, speculative and unsubstantiated claims." in a three-page paper
    , Oxitec accused the paper of not finding "any material negative impact on the local population or environment" and of misleading speculation.
    long before the actual release in the wild, in-house tests showed that the "lethal gene" inserted into OX513A did not kill 100 percent of the mosquito offspring, and that there was still a small chance that the offspring would survive. A spokesman for
    said the company was "very aware of this."
    also refutes the reference in the paper to "mating bias": about 1 billion genetically modified male mosquitoes have been placed worldwide, and no one has ever observed "mating bias."
    controversy continues, and some scientists who have no interest in Oxitic have come forward to question the paper.
    Jason Rasgon, an entomologist at Pennsylvania State University, acknowledges the importance of the genetic findings in the paper, but says some of the speculations are exaggerated and irresponsible.
    Rasgon, the authors should stress in their paper that no lethal and fluorescent protein genes found in genetically modified mosquito DNA have been found in newly born mosquitoes.
    the new genes now found in the Jacobina mosquito population are nothing more than the "genetic background" of the OX513A male mosquito, the OX513A gene that already has some from the Cuban and Mexican populations.
    Powell's team speculated that new mosquitoes with three-country ancestry "may" be more difficult to deal with than existing species, but Rasgon points out that such guesses lack data.
    Rasgon is concerned that the paper may inspire scepticism about GMOs, and wants clarification.
    In view of the criticism and questioning of the paper's conclusions, the editor of the Scientific Report added a statement to its website on 17 September that it would respond to these questions in the near future.
    the ongoing experiments, Oxitec hasn't stopped doing research.
    they have made a series of improvements to enable second-generation genetically modified mosquitoes to spread the deadly gene more effectively.
    unlike in the past, a new generation of lethal genes kills only blood-sucking female offspring, while male offspring survive so that they can continue to pass on the lethal genes.
    in June, Oxitec announced that their field trials in Brazil had been a huge success, with mosquito populations down 96 percent.
    Texas and Florida are also considering using Oxitec's genetically modified mosquitoes to control local mosquito populations.
    recently, Oxitec recently provided authorities in the United States with their new genetically modified mosquitoes for review. On September 11,
    , the U.S. Environmental Protection Agency made its application public for comment.
    once approved, the new mosquitoes will soon be released for the first time in the Florida Keys.
    Source: Global Science.
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