Researchers introduce CRISPR to enable gene editing in cockroaches

According to a study released by Cell Press on May 16th, 2022, in the journal Cell Reports Methods, scientists have created a CRISPR-Cas9 technique to facilitate gene editing in cockroaches. The “direct parental” CRISPR (DIPA-CRISPR) approach, which is straightforward and effective, involves injecting materials into female adults where eggs are growing rather than into the embryos directly.

Researchers introduce CRISPR to enable gene editing in cockroaches
Cartoon of CRISPR in cockroaches. Image Credit: Shirai et al. /Cell Reports Methods

In a sense, insect researchers have been freed from the annoyance 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.”

Takaaki Daimon, Study Senior Author, Kyoto University

Insect gene editing now relies on microinjection of materials into early embryos, which limits its application to a small number of species. Cockroaches, for instance, have a distinct reproductive system that has prevented genetic manipulation in the past. Insect gene editing also frequently necessitates costly equipment, a unique experimental setting for each species, and professionally experienced laboratory personnel.

These problems with conventional methods have plagued researchers who wish to perform genome editing on a wide variety of insect species.”

Takaaki Daimon, Study Senior Author, Kyoto University

To get over these constraints, Daimon and his colleagues used Cas9 ribonucleoproteins (RNPs) inserted into the main body cavity of adult female cockroaches to induce heritable mutations in maturing egg cells. The findings showed that gene editing efficiency—the percentage of modified people among the overall population hatched—could be as high as 22%.

DIPA-CRISPR was found to be more than 50% effective in the red flour beetle. Furthermore, the researchers created gene-knocking beetles by inserting single-stranded oligonucleotides and Cas9 RNPs together; however, the effectiveness is low and needs to be increased.

DIPA-effectiveness CRISPRs in two evolutionarily distinct species illustrate their potential for widespread usage. However, the method does not apply to all insect species, especially fruit flies. Furthermore, the trials revealed that the stage of the adult females implanted is the most important factor in success.

As a response, DIPA-CRISPR necessitates a thorough understanding of ovarian development. Given the different life cycles and reproductive techniques of insects, this can be difficult in some species.

Despite these drawbacks, DIPA-CRISPR is widely available, extremely practical, and may easily be implemented in laboratories, allowing gene editing to be applied to a wide range of model and non-model insect species.

For adult injection, the approach requires only two components: Cas9 protein and single-guide RNA, considerably simplifying gene-editing processes. Furthermore, ordinary Cas9, which is commercially accessible, can be used for adult injection, removing the requirement for time-consuming customized protein engineering.

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

Takaaki Daimon, Study Senior Author, Kyoto University

In principle, it may be also possible that other arthropods could be genome-edited using a similar approach. These include agricultural and medical pests such as mites and ticks, and important fishery resources such as shrimp and crabs,” Daimon added.

Source:
Journal reference:

Shirai, Y., et al. (2022) DIPA-CRISPR is a simple and accessible method for insect gene editing. Cell Reports Methods. doi.org/10.1016/j.crmeth.2022.100215.

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