- Courtesy of Ashley Rasys
- Scientists have used Crispr technology to genetically edit a reptile for the first time.
- A new study describes how the team tweaked the genes of 146 brown anole lizard embryos.
- The scientists created four albino lizards – each no bigger than a finger when they hatched. The lack of pigmentation was a sign that the gene-editing trial worked.
- Researchers have used Crispr to alter chicken, pig, cow, and fish genes. But this is the first time the technology has been used on reptiles.
- Gene-edited reptiles could be used to help test therapeutic drugs or control invasive species in the Everglades.
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Over the past several years, researchers have successfully modified chicken, pig, cow, mouse, and even fish genes using Crispr technology.
Crispr, which was first patented in 2012, allows scientists to tweak individual genes and change DNA sequences inside cells. The tool can be used to create pest-resistant genetically-modified crops, correct genetic defects like blindness, treat cancer, and breed malaria-free mosquitoes.
But reptiles like snakes, lizards, and crocodiles were considered off the gene-editing table because of the creatures’ unusual reproductive systems.
A group of scientists at the University of Georgia have successfully altered the genes of four brown anole lizards, which were born lacking the typical brown pigment from which the species derives its name.
“The whole field of developmental genetics has left reptiles in the dust,” Douglas Menke, a study co-author and an associate professor of genetics at the University of Georgia, told Science magazine in March.
These genetically modified lizards, however, are changing that.
- Doug Menke
“Needless to say, we were both jazzed about the addition to the lab,” Ashley Rasys, a graduate student in the University of Georgia’s cellular biology department and lead author of the study, told Business Insider.
The lack of pigment showed that the gene-editing worked
Rasys and Menke chose to attempt gene-edits on the brown anole lizard, or Anolis sagrei, because of its small size, long breeding season, and the frequently with which females lay eggs.
The scientists used the Crispr technology to modify the females’ unfertilized eggs while they were still in the ovaries, then the animals mated and bred naturally.
The team targeted a gene responsible for the enzyme tyrosinase, which affects the lizard’s color. If that gene were to be de-activated, the hatchlings should come out without pigment. So an albino lizard was a sure sign that the scientists’ gene-tweak had worked.
The scientists edited genes in 146 eggs from 21 lizards, and waited three months for the lizards to hatch. Four of those eggs yielded albino reptiles.
Unfortunately, Rasys and Menke were in a meeting during the historic hatching.
“Another member of our research group witnessed the hatchling emerge from its egg,” Menke told Business Insider. “I received a text message with a photo of our first albino lizard while I was in a meeting. Needless to say, I excused myself from the meeting as soon as I could.”
Rasys, too, said she witnessed her first glance of the team’s “new arrival” through that same text message.
- Hannah Schriever, courtesy of Ashley Rasys
Menke said the gene-editing produced both male and female lizards, some 2 inches in length (though more than half of that length comes from the creatures’ long, skinny tails).
While the lizards don’t have names, each lizard receives a unique ID to help the scientists track them.
Genetically modified lizards could help test drugs and control invasive reptiles
For Menke and Rasys, this achievement means more than just a bucking of one of Crispr’s longstanding limitations.
“There is a whole universe of unstudied biology in these animals,” Menke said. “Gene editing is the most direct way to explore gene function in these species.”
There are over 10,000 described species of reptiles, and the genome of each contains around 25,000 genes, he added.
Studying reptile genes can improve scientists’ understanding of human biology, too. For example, people who are born without pigment, much like these anole lizards, also tend to have poor eyesight due to defects in their eyes. The major cause of these vision problems is that the fovea (a pit-like depression in the human eye that enables sharp, clear eyesight) is absent or under-developed in albino people, Menke said. But most animals used for genetic studies (like mice) lack a fovea, and therefore can’t be used to study foveal defects.
But the lizards Menke and Rasys’ team are working with have fovea.
“Finally we have an animal that we can use to understand human foveal defects,” Menke said.
The ability to tweak lizard genes could therefore allow scientists to better identify therapeutic targets and test drugs in developing lizards, Rasys said.
- Hannah Schriever, courtesy of Ashley Rasys
Menke added that gene editing could be used in animal conservation efforts, too. Invasive reptiles – particularly those in Florida, like the Burmese pythons in the Everglades – can harm native wildlife.
“There are certain gene editing approaches that might be used to help control some of these invasive species of reptile,” Menke said.