For the first time, CRISPR-Cas9 has been used to create mutant reptiles, researchers reported August 27 in Cell Reports. Typically, scientists inject CRISPR-Cas9 gene-editing reagents into zygotes or fertilized eggs, but because lizards fertilize their eggs internally and at unpredictable times, these methods cannot be applied. Instead, this team injected the reagents into unfertilized eggs held in anole lizards’ ovaries to knock out the gene for the enzyme tyrosinase, thus rendering their offspring albino.
“Because we are injecting unfertilized eggs, we thought that we would only be able to perform gene editing on the alleles inherited from the mother,” says Doug Menke, a geneticist at the University of Georgia, in an announcement. But when the mutant lizards hatched three months later, about half showed signs of gene editing events on both the maternal and paternal alleles, suggesting that the reagents remain active for days or weeks after injection. About six to nine percent of the modified oocytes produced offspring with recoded genes—a level of efficiency that seems low compared to model organisms but sets a new record in reptiles.
A.M. Rasys et al., “CRISPR-Cas9 gene editing in lizards through microinjection of unfertilized oocytes,” doi:10.1016/j.celrep.2019.07.089, Cell Rep, 2019.
Nicoletta Lanese is an intern at The Scientist. Email her at email@example.com.