For the first time in human history, a team of researchers from the University of Georgia has genetically modified reptiles using the CRISPR Cas-9 gene-editing tool - specifically to create four albino lizards.
Why choose reptiles for this study?
"Reptiles are very understudied in terms of their reproductive biology and embryonic development," said Douglas Menke, associate professor in the department of genetics at the University of Georgia.
"There are no good methods to manipulate embryos like we can easily do with mammals, fish or amphibians. To our knowledge, no other lab in the world has produced a genetically altered reptile," continued Menke.
Furthermore, by conducting the study on lizards, and specifically in this instance, Anolis sagrei, or brown anoles, could lead to implications for human genetics.
Eye development, in particular, would benefit from this research, as the tyrosinase gene, the one edited in this study is also the one that gives us pigmentation in our skin. The enzyme is needed to control melanin and is required for eye development in both humans and anoles. However, it is "absent in the eyes of mice and other organisms commonly used for biomedical research," notes the University of Georgia press release.
Now, researchers interested in finding ways to manipulate this gene have a suitable animal model - something that was impossible until now.
What did CRISPR do to the lizards?
CRISPR is a gene-editing tool, and in this instance, it was injected into the lizards' fertilized eggs. This, in turn, caused a mutation in the DNA of all subsequent cells.
Menke's team microinjected CRISPR proteins into a number of immature eggs, or oocytes, still located in the lizards' ovaries. In doing so, the team injected 146 oocytes from 21 lizards and waited for the eggs to fertilize naturally.
In just a few weeks the team discovered they had been successful. Four offspring displayed albinism traits, which is what happens when tyrosinase is inactivated.
"When I saw our first albino hatchling, it was truly awe inspiring," said student Ashley Rasys, who was the first author on the study.
"I’m most excited about the possibility of expanding this approach into many other reptilian model systems, effectively opening the doorway for future functional studies."
The team's results have been published in Cell Reports on Tuesday.