For the first time, scientists have edited the genes of cockroaches to create ‘knockout cockroaches’.
Researchers have successfully used CRISPR, a gene editing technology, on cockroaches in a first that opens the door to future gene-editing research on insects.
CRISPR allows scientists to target a specific bit of DNA inside a cell and then alter it. This technology was a breakthrough for research into evolutionary biology and disease treatments, earning it the 2020 Nobel Prize in Chemistry.
The ‘knockout cockroaches’ essentially have artificially inactivated genes, opening up applications for the technology to be used on other insects for pest control and evolutionary biology.
They are labelled ‘knockout’ because part of their DNA has been ‘knocked out’.
While scientists have previously used CRISPR on other species, it was impossible until now to apply it to insects like cockroaches that have inaccessible embryos.
Cockroaches shield their fertilised eggs in hard cases for days or weeks until the offspring hatch. Due to this ‘unique reproduction system, it is impracticable to inject materials into very early embryos’ for gene editing.
Scientists at Kyoto University, have instead managed to inject genetic materials into adult female cockroaches to produce mutant offspring, according to a study published this week in Cell Reports Methods.
Using an approach called ‘direct parental’’ CRISPR (DIPA-CRISPR), researchers successfully demonstrated that both cockroach and beetle offspring contained artificially edited genes when their mothers were subjected to the injections.
The ‘mutant’ cockroach offspring created using this method also passed the artificial mutations onto the next generation on mating.
‘Current approaches for insect gene editing require microinjection of materials into early embryos, which is highly challenging in most species. In this work, we established and optimized a simple and efficient method for insect gene editing by adult injection, which can be readily implemented in any laboratory and directly applied to a great diversity of non-model insect species,’ wrote Yu Shirai, the lead scientist on the study.
The study was inspired by similar ones that achieved this technique in mosquitoes and wasps.
After running several experiments that introduced genes for eye color into the cockroach species Blattella germanica, the team found that up to 21.8% of offspring inherited the artificial mutations, ‘which easily enabled the first establishment of knockout cockroach lines’ reports the study.
The researchers also discovered that when the DIPA-CRISPR was applied to the red flour beetle Tribolium castaneum, as much as 50% of the offspring inherited the mutant genes.
The team also produced ‘knockin’ beetles — carrying genes that were artificially inserted into their DNA — in contrast to knockout organisms that carry artificially inactivated genes.
The results could provide a valuable foundation for pest management using gene editing.
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