The MIT Technology Review reports that a team of scientists at the Riken Institute in Japan have made history by successfully bio-engineering albino possums, using CRISPR. This seems like a strange accomplishment, but as the magazine explains:
CRISPR has been used to modify the genes of tomatoes, humans, and just about everything in between. Because of their unique reproductive biology and their relative rarity in laboratory settings, though, marsupials had eluded the CRISPR rush—until now.
The difficulties of genetically modifying marsupials had less to do with CRISPR than with the intricacies of marsupial reproductive biology, says Hiroshi Kiyonari(link in Japanese), the lead author of the new study.
While kangaroos and koalas are more well-known, researchers who study marsupials often use opossums in lab experiments, since they're smaller and easier to care for. Gray short-tailed opossums, the species used in the study, are related to the white-faced North American opossums, but they're smaller and don't have a pouch.
Why possums? It's possible the scientists were moved and inspired by songwriting John Darnielle's achingly beautiful marsupial lament, "Possum By Night." Or it could be the fact that possums are often used in laboratories as models for certain human diseases, because they're the only mammals that also get things like melanoma. It also only takes about 14 days to gestate a new possum, so it's pretty short time span for seeing if your animal experimentation worked or not.
The "albino" part is much more practical. It's the same reason scientists have previously CRISPR'd glow-in-the-dark rabbits and puppies: it makes it a lot easier to tell if you got your genomic mapping right and experimentation worked. If the scientists later decide to edit other genes, it'll also make it easier to observe the animal over the long term while comparing it to its other, non-gene-edited kind — just look for the one that looks different, and see how it's doing!
Anyway I'm going to go re-write this Mountain Goats song to be about experiments on lab animals:
An albino opossum proves CRISPR works for marsupials, too [Casey Crownheart / MIT Technology Review]