An albino opossum proves that CRISPR also works for marsupials

Although kangaroos and koalas are more popular, researchers studying marsupials often use opossums in laboratory experiments because they are smaller and easier to care for. The gray short-tailed opossums used in the study are associated with white-faced North American opossums, but are smaller and lack a wallet.

Researchers at Riken used CRISPR to eliminate or exclude a gene that encodes pigment production. If the targeting of this gene were to work on experiments, the results would be obvious at a glance: opposites would be albino if two copies of the gene were expelled, and painted or mosaic if only one copy were deleted.

The rubbish obtained included an albino opossum and a mosaic opossum (pictured above). The researchers also grew both, and as a result, created a whole host of albino opossums, showing that coloration was an inherited genetic trait.

The researchers had to navigate some obstacles to edit the opossum genome. First, they had to determine the timing of hormone injections to get the animals ready for pregnancy. Another challenge was that the marsupial eggs soon fertilize and develop a thick layer around them, called the mucoid shell. This makes it difficult to inject CRISPR treatment into cells. In the first attempts, the needles would not enter the cells or cause damage, so the embryos could not survive, Kiyonari says.

The researchers realized that it would be much easier to do the injection earlier, before there was a very hard coating around the egg. When the lights in the labs were turned off, the researchers were able to combine the opossums in the evening so that the eggs would be ready to work in the morning, about a day and a half later.

The researchers then used a tool called a piezoelectric drill, which uses an electric charge to make it easier to insert into the membrane. This helped them inject the cells without harming them.

“I think the result is tremendous,” he says Richard Behringer, Geneticist at the University of Texas. “They have shown that it can be done. Now is the time to do biology,” he added.

Opossums have been used as laboratory animals since the 1970s, and researchers have been trying to edit their genes for 25 years, says VandeBerg, who in 1978 began trying to create the first opossum colony in the laboratory. They were also their first marsupials. fully sequenced genome, 2007an.

Comparative biologists hope that the ability to genetically alter opposites will help them learn more about certain specific aspects of as yet undecoded marsupial biology. “We find genes and marsupial genes that we don’t have, so a little bit of mystery arises about what they’re doing,” he says. Rob Miller, An immunologist at the University of New Mexico, who uses opossums in his research.