A team from the University of Georgia manipulated the genes of Anolis lizards, common in the Caribbean, to obtain albino specimens, according to a study published yesterday by the journal Cell Reports.
The purpose of this genetic engineering exercise, according to Doug Menke, an associate professor at the University of Georgia, is the study of genetic functions themselves and, ultimately, the possible transfer of that “edition” to other animals.
“For a good time we have already tried to modify reptile genomes and manipulate genes in reptiles, but we were stuck as to how the genetic editing is done in larger model systems,” explained the researcher.
“We wanted to explore anole lizards to study the evolution of genetic regulation since these animals have experienced a series of specializations in the Caribbean islands very similar to the adaptations of the finches birds in the Galapagos,” he added.
The researchers used the CRISPR-Cas9 method of genetic editing, by which the genomes of living organisms can be modified and usually consists of injecting reagents into freshly fertilized eggs or unicellular zygote.
This technique cannot be used in reptiles because lizards have internal fertilization and the timing of fertilization cannot be predicted, Menke explained.
Also, a monocellular embryo of a female lizard cannot be easily transferred, which makes manipulation outside the animal almost impossible, he added.
But Menke and his collaborators noted that the transparent membrane around the ovary allowed them to see the whole process of egg development, including which of them were ready to be ovulated and fertilized.
Therefore, they decided to inject CRISPR reagents into the unfertilized eggs that were inside the ovaries to see if they had any effect.
“Since we injected the unfertilized eggs, we thought we could carry out gene editing only in the inherited alleles of the mother. There is no deoxyribonucleic acid (DNA) from the father in those unfertilized eggs, ”explained the researcher.
An allele is each of the expressions that can have the same gene differentiated in its sequence and that can lead to specific changes in the function of that gene, for example, variations in hair color or blood group.
The scientists had to wait three months for the lizard pups to hatch and then found that almost half of the mutant lizards had genetic changes in both maternal and paternal alleles.