While kangaroos and koalas are extra well-known, researchers who research marsupials typically use opossums in lab experiments, since they’re smaller and simpler to look after. Gray short-tailed opossums, the species used within the research, are associated to the white-faced North American opossums, however they’re smaller and don’t have a pouch.
The researchers at Riken used CRISPR to delete, or knock out, a gene that codes for pigment manufacturing. Targeting this gene meant that if the experiments labored, the outcomes can be apparent at a look: the opossums can be albino if each copies of the gene have been knocked out, and mottled, or mosaic, if a single copy was deleted.
The ensuing litter included one albino opossum and one mosaic opossum (pictured above). The researchers additionally bred the 2, which resulted in a litter of absolutely albino opossums, displaying that the coloring was an inherited genetic trait.
The researchers needed to navigate a couple of hurdles to edit the opossum genome. First, they needed to work out the timing of hormone injections to get the animals prepared for being pregnant. The different problem was that marsupial eggs develop a thick layer round them, known as a mucoid shell, quickly after fertilization. This makes it more durable to inject the CRISPR remedy into the cells. In their first makes an attempt, needles both wouldn’t penetrate the cells or would injury them so the embryos couldn’t survive, Kiyonari says.
The researchers realized that it will be rather a lot simpler to do the injection at an earlier stage, earlier than the coating across the egg acquired too robust. By altering when the lights turned off within the labs, researchers acquired the opossums to mate later within the night in order that the eggs can be able to work with within the morning, a couple of day and a half later.
The researchers then used a instrument known as a piezoelectric drill, which makes use of electrical cost to extra simply penetrate the membrane. This helped them inject the cells with out damaging them.
“I think it’s an incredible result,” says Richard Behringer, a geneticist on the University of Texas. “They’ve shown it can be done. Now it’s time to do the biology,” he provides.
Opossums have been used as laboratory animals because the Seventies, and researchers have tried to edit their genes for a minimum of 25 years, says VandeBerg, who began attempting to create the primary laboratory opossum colony in 1978. They have been additionally the primary marsupial to have their genome absolutely sequenced, in 2007.
Comparative biologists hope the power to genetically modify opossums will assist them study extra about a number of the distinctive points of marsupial biology which have but to be decoded. “We find genes and marsupial genomes that we don’t have, so that creates a bit of a mystery as to what they’re doing,” says Rob Miller, an immunologist on the University of New Mexico, who makes use of opossums in his analysis.