Author: Tina Hesman Saey / Source: Science News
Scientists are getting closer to creating a genetic pest-control measure against rodents.
Female mice engineered to carry a genetic cut-and-paste machine called a gene drive may be able to pass a particular version of one gene on to more than 80 percent of their offspring, researchers report January 23 in Nature. That rate would beat the usual 50 percent chance of handing down a gene variant, first reported in 1865 by Gregor Mendel from his studies of peas.
“What we’ve done is engineered a gene that can be inherited more frequently than it would be by normal Mendelian inheritance,” says Kimberly Cooper, a developmental geneticist at the University of California, San Diego. “My graduate student likes to call it ‘cheating Mendel.’”
Such engineered genetic cheats have been proposed to wipe out disease-carrying mosquitoes and invasive species by targeting genes involved in reproduction (SN: 12/12/15, p. 16). Gene drives might also be used to prevent pests from carrying diseases, such as malaria (SN: 12/26/15, p. 6). Researchers have made successful gene drives in laboratory experiments in mosquitoes, fruit flies and yeast.
But no one has yet built one that works in a mammal. And Cooper isn’t claiming to have done so either. By definition, a gene drive must cheat Mendelian inheritance rules over multiple generations, spreading itself to an entire population. Cooper’s group has produced one generation of genetic cheater mice, but hasn’t yet tracked the gene drive’s spread through multiple generations.
“It’s the prototype experiment you need for a drive in rodents,” says Thomas Prowse, a population ecologist at the University of Adelaide in Australia who was not involved in the study.
Gene drives use a molecular scissors known as CRISPR/Cas9 to insert themselves into a particular site in an organism’s DNA. A gene drive usually contains instructions for making the Cas9 enzyme, which cuts DNA, and a guide RNA that shepherds the enzyme to a particular gene. When Cas9 slices the DNA, cells can repair the break by copying the version of the gene containing the gene drive from its sister chromosome. That copying ensures that all offspring will inherit the gene drive.
Cooper and colleagues built half of a gene drive: They inserted instructions for making a…
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