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Ashley M. Rasys and Hannah C. Schriever
By Jon Cohen
CRISPR, the powerful genome editor, is not as powerful in lizards and snakes: it has never been used to edit the embryos of these reptiles. Researchers have developed a workaround by modifying immature and unfertilized eggs of brown anus lizards.
Researchers usually alter with CRISPR by injecting it into a unicellular fertilized egg, thus creating a change in the DNA present in all subsequent cells. Female anoles, however, are a particular challenge: they store sperm in their oviducts for long periods of time, making it difficult to plan for the introduction of CRISPR at fertilization. They also form an eggshell during fertilization and it is extremely difficult to insert a needle at this stage without damaging the embryo.
Researchers at the University of Georgia (UGA) in Athens have therefore injected the CRISPR complex into immature eggs still in the ovaries, targeting a gene that produces tyrosinase, an enzyme that affects pigmentation. After modifying 146 immature eggs from 21 lizards, the scientists got their reward: four albino descendants, they reported in a pre-print published this week on bioRxiv. In order for the color change to occur, maternal and paternal genes must have mutated, suggesting to researchers that CRISPR modified the genes of the egg and then remained stuck, paralyzing paternal genes after fertilization.
Tony Gamble, an evolutionary biologist who studies gecko at Marquette University in Milwaukee, Wisconsin, said on Twitter that this new technique, which scientists say, will likely work in many other species. lizards and snakes. Douglas Menke of UGA, the mouse development geneticist who led the experiment, was more specific: "The whole field of developmental genetics has left reptiles in the dust." So far.
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