Since it burst onto the scene in 2012, genome editing with CRISPR has opened up a world of possibilities in medicine and engineering, from the production of biofuels to the treatment of genetic diseases through personalized gene therapy. In the lab, CRISPR has been used to learn about the biology of many fish, bird, amphibian, and mammalian species. Now, Douglas Menke’s team of scientists at the University of Georgia have used CRISPR to generate the first genome edited reptiles.

With most species, CRISPR components are injected into freshly fertilized embryos, allowing both the paternally and maternally inherited copies of the genome to be edited. However, female reptiles carry sperm in their reproductive system for long periods, making it difficult for scientists to predict the time of egg fertilization.  To circumvent this problem, Menke’s team took advantage of the anatomy of Anolis sagrei lizards, including a transparent membrane over the ovary that allowed them to visualize which eggs were next in line to be fertilized. They then injected CRISPR components targeting the tyrosinase gene—whose deletion in both copies results in albinism—into unfertilized eggs.  To the team’s surprise, they observed that several offspring lizards were albino, suggesting that the CRISPR components stuck around in the eggs long enough to edit the paternally inherited genome after fertilization.

Humans with albinism often struggle with vision problems. Interestingly, humans and lizards have similar visual systems, including the presence of a structure in the eye called the fovea that is necessary for high-acuity vision. Now, the albino lizards generated in this study can be used as a new model system to study the underlying connection between albinism and vision impairment. In addition, Anolis lizards have experienced extensive diversification over time, with hundreds of species now identified. The newfound ability to carefully study them through genome editing paves the way for an unprecedented understanding of reptilian evolution and physiology.    

For more information: To read more about how CRISPR genome editing works, check out this SITN article!

Managing Correspondent: Benjamin Andreone

News Article: These albino lizards are the world’s first gene-edited reptiles. Phys.org

Original Article: CRISPR-Cas9 Gene Editing in Lizards through Microinjection of Unfertilized Oocytes. Cell Reports

Image Credit: Doug Menke/University of Georgia

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