Tiny Albino Lizards Are the First Gene-edited, Mutant Reptiles

Scientists have genetically modified reptiles for the first time, to create tiny mutant albino lizards.

The team used the CRISPR-Cas-9 technique to edit the DNA of the Anolis sagrei, or brown anole lizard, which is around the size of an index finger. Of the eggs used in the study, between 6 to 9 percent of themj were born with the gene-edited traits.

These animals also passed on their edited genes to their children, the study published in the journal Cell Reports shows.

Co-author Doug Menke, associate professor in the department of Genetics at the University of Georgia, explained in a statement relative to other animals where editing can be up to 80 percent effective, 6 percent "seems low, but no one has been able to do these sorts of manipulations in any reptile before."

CRISPR-Cas-9, also known as CRISPR, is used to change the DNA of an organism by adding, cutting away or changing parts of its genome. Scientists hope the groundbreaking approach could be used to create treatments for a range of conditions, but the use of gene editing on humans is highly controversial and illegal in many countries.

Menke explained in a statement that in most animals the CRISPR mixture is injected into newly fertilized eggs or zygotes made up of one cell. But due to the way reptiles reproduce, experts can't predict when this will happen. What's more, it's hard to safely extract an embryo containing a single cell from a female lizard.

To get around this problem, the researchers took advantage of the transparent membrane covering the lizard's ovary. This enabled them to predict which eggs were next in line to be fertilized, and use CRISPR on unfertilized eggs.

As the team were injecting unfertilized eggs, they expected to only be able to edit the gene variants inherited from the mother.

"We had to wait three months for the lizards to hatch, so it's a bit like slow-motion gene editing," Menke said. Using the term allele, a variant form of a gene, he explained: "But it turns out that when we did this procedure, about half of the mutant lizards that we generated had gene-editing events on the maternal allele and the paternal allele."

The researchers believe this shows the CRISPR worked for days or weeks in the eggs.

In humans, albinism can cause eye problems. So the scientists hope the lizards could be used to study how the retina develops in this condition, and develop treatments.

Menke told Newsweek that humans with albinism often have a missing or under-developed fovea, a pit-like depression in the organ important for high acuity vision. While mice, commonly use for genetic studies, don't have a fovea, the anole lizard does. They use it to hunt insects.

"Although gene-editing has been performed in many animals, there are no reports of anyone performing gene-editing in reptiles," Menke told Newsweek. "Yet there are over 10,000 described species of reptile, and the genome of each species contains around 25,000 protein coding genes. There is a whole universe of unstudied biology in these animals."