16 November 2017

Semi-finished products for genetic engineering

Scientists have created three-eyed mosquitoes


A group of researchers from the University of California, Riverside has created transgenic Aedes aegypti mosquitoes that are capable of producing the Cas9 protein. This protein is used in the popular CRISPR/Cas9 genome editing system, so scientists were able to purposefully change the DNA of these mosquitoes. To prove the effectiveness of the method, by editing the genes associated with the development of cuticles, eyes and wings, they obtained yellow, three-eyed and wingless mosquitoes.

The yellow-horned mosquito (Aedes aegypti) can carry pathogens not only of yellow fever, mentioned in its name, but also spreads viruses of dengue, chikungunya, Zika fever. As these mosquitoes quickly acquire resistance to chemical insecticides, scientists are trying to find genetic methods to combat them.

Previous attempts to use genome editing for this purpose proved to be insufficiently effective due to poor mosquito survival and poor transmission of modified genes to offspring. Entomologist Omar Akbari and his colleagues have now been able to obtain transgenic mosquitoes that stably express the Cas9 enzyme at the larval stage of development. This protein in bacterial cells is used to destroy foreign DNA, for example, the DNA of a virus that has penetrated a bacterium. An indication of the target of this protein is given by a special control RNA molecule, in which the desired sequence of nucleotides is recorded. If, during the development of a mosquito, the Cas9 protein is constantly produced in its cells, then its genes can be easily affected. In the current study, the authors used this protein to destroy genes that control the development of various organs of the mosquito. As a result, they obtained mosquitoes with a third eye, anomalies in the development of wings, unusual eye color or body coverings.


One example of directed mutations: the destruction of genes associated with cuticle pigmentation led to a change in the color of the trunk from black to yellow, and the destruction of genes associated with eye pigmentation changed their color from black to white – VM.

In the future, the same method can be used to disrupt the ability of mosquitoes to reproduce, which serves as the most reliable way to reduce their numbers.

The results of the study are published in the journal Proceedings of the National Academy of Sciences (Li et al., Germline Cas9 expression yields highly efficient genome engineering in a major worldwide disease vector, Aedes aegypti).

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