New CRISPR method makes gene editing in insects child’s play

Insects have complex anatomical features due to which the process of gene editing in many insect species like cockroaches has always been tricky for scientists. But a study recently published in the journal Cell press reveals a promising solution to this problem.

Conceptual image of CRISPR in cockroaches. Image credits: Shirai et al./Cell Reports Methods

A team of researchers from Kyoto University in Japan has developed a technique called direct-parental CRISPR (DIPA). According to their study, this CRISPR method (the already famous “genetic scissor” can be used for gene editing in more than 90% of insect species. Such a method could help scientists around the world to overcome the various limitations and complications they face every time they try to edit an insect’s genome.

Discussing the research, the study’s lead author and professor of agriculture at Kyoto University, Takaaki Daimon, said:

“In a sense, insect researchers have been freed from the hassle of egg injections. We can now edit insect genomes more freely and at will. In principle, this method should work for more than 90% of insect species.

Why Bother Editing Bugs

A Smithsonian Institution report reveals that there are 900,000 species of insects (some other reports suggest the number could be as high as 1.5 million) and in terms of population they are the largest group on Earth. The total number of insects at any given time is thought to be 10 quintillion (1019). Insects are closely related to agriculture, disease, and various ecosystem services such as decomposition, pollination, and pest control that directly affect humans. Simply put, they shape the nature we see around us.

Moreover, we derive endless commercial benefits from insects in the form of medicines, textiles, edibles, and more. Genome editing practices in insects allow scientists to experiment with their genetic makeup and gain more information about their impact on nature and humanity, but so far it has been a very difficult.

First, current methods of genetic modification are very expensive because they require high-end setup and equipment. Second, they can only be used for a limited number of insect species such as mosquitoes and butterflies, since they require the introduction of mutations in the early embryonic stages. Since many insects (like cockroaches) have complex reproductive systems and hard early embryonic shells, injecting the desired material into their embryonic cells either becomes impossible or requires special tools and skills.

Therefore, different gene editing approaches are often required in the case of different insect species depending on their anatomical and reproductive characteristics.

“These problems with conventional methods have plagued researchers who want to perform genome editing on a wide variety of insect species,” adds Daimon.

The benefits of direct-parental CRISPR in insects

DIPA or direct-parental CRISPR is a method of regularly spaced short palindromic repeats (CRISPR)-Cas9. It is a very efficient and less time-consuming gene-editing technique that involves the use of a piece of guided RNA (gRNA) and the Cas9 enzyme. The gRna detects the part of the DNA genome that scientists want to modify in an organism and the Cas9 enzyme cuts the DNA strands containing the targeted genome.

Image credits: Virvoreanu-Laurentiu/Pixabay

When DNA is damaged, cells in the organism’s body initiate a repair mechanism and ultimately the original strand is replaced with the desired modified DNA. Professor Daimon and colleagues from Kyoto University performed an experiment with adult female cockroaches using the DIPA CRISPR-Ca9 method. Instead of inserting the desired genetic material at the early embryonic stage, they modified the genes of female cockroaches by injecting Cas9 ribonucleoproteins (RNPs) into their body segment containing developing eggs.

After making changes to cockroach genomes, the researchers found that the percentage of successful mutations was around 22%. When they used the same technique on red flour beetles, the effectiveness increased to 50%. Interestingly, cockroaches and red flour beetles are not closely related to each other, suggesting that the successful implementation of DIPA-CRISPR indices could be used for gene editing in different species of insects. ‘insects.

Another advantage of the DIPA CRISPR technique is that it requires no expensive equipment and can be easily performed with a piece of gRNA and the Cas9 enzyme using a basic experimental setup. However, the technique is not yet fully developed and further research is needed before it can be applied for genetic modification in all insect species.

“By improving the DIPA-CRISPR method and making it even more efficient and versatile, we may be able to enable genome editing in nearly all of the more than 1.5 million insect species, opening up a future in which we can fully utilize the incredible biological functions of insects,” Daimon said.

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