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Replace Mouse/Rat Scientific Model Animal

They've done their stint, time to sub in something much more convenient
  (+6, -1)
(+6, -1)
  [vote for,

Science has a number of model organisms. The perennial classics are:

Escherichia coli, a prokaryotic bacteria we found in our own guts,

Saccharomyces cerevisiae, a single celled eukaryote we found in the nearest bakery,

Caenorhabditis elegans, a small nemotode worm found in the nearest soil sample

Drosophila melanogaster, a small fly we found buzzing around the nearest fruit bowl

Danio rerio, a small omnivourous fish native to northern India, but probably used because it was a common aquarium fish.

The mouse: Mus musculus, likely found running around in Robert Hooke's kitchen

The Rat: Rattus norvegicus, found all over europe as a pest.

The point I'm making, is that these organisms were not rationally selected, they were chosen for convenience. They're easy & cheap to grow/breed, their life cycles are usefully short. Pigs would be a much more apporopriate model for human metabolism, anatomy, immunology and much more, but they're huge, long-lived, they eat a lot and can be dangerous. You can get so much more work done in mice*. That we have acquired an enormous amount of information on them is just a consequence of their extensive use.

During the early days of genome research (~15-30 years ago), sequencing the vast amount of DNA in human cells was extremely laborious and expensive, it took a decade or so to get 3% of one. As the human genome sequence was assembled, lots of work went into parallel sequencing efforts in mice and rats. This allowed comparison and ultimately the creation of mouse models of human genetic diseases. For this reason: the hard-won genetic data on human, mouse & rat genomes, switching away from mouse/rat models 20 years ago would have been a staggeringly stupid idea.

Nowadays, the cost to sequence a whole genome is about $5k. That's a huge shift, a decade, billions of $ to a one-week mail-in service for $5k. Trivial in the grand scheme of things, and as such almost everything of interest has been sequenced.

Now, the problem. Laboratory mouse and rat models are expensive. Animal facilities just EAT budget. At a minimum, a mouse is about $1/day, a rat about $4. Now, if you have a genetic knock out model, you need breeding colonies of both the model, and the appropriate genetic control. You might have 5 related genetic models, meaning 6 colonies. If you're using animals for tissue isolation, you have to get ahead and make sure you have a large enough breeding colony ahead of time. This gets tricky, mice age fast, you don't want to use old animals that give strange results, or have your colony get so old as to be infertile. You have to manage this incredibly carefully, walking the line between not having enough animals, having them age-out, and potentially losing your expensively-created genetic model and wasting $50k/year on excess animals. It can and does break labs financially.

So, the solution. We switch to the 13-lined ground squirrel. This is a rodent native to central N. America. Usefully, it's genome is sequenced, however most the remarkable thing is that it hibernates. When hibernation (torpor) is induced, it's body temperature falls to 2-8C and it's heart rate down to 2-5bpm. IT can stay like this for weeks. Occasionally they need a brief 12-24hr periods where they warm up before starting another torpor cycle up to (& possibly more than) 6 months. This would be an incredibly useful feature for a research model rodent. You could pause/activate some/all of your colony at will. Instead of a group of cages serviced daily, we could have a something like a ventilated refrigerator. Instead of paying $900 to ship one mouse to another lab (because we have to guarantee speed, ventilation, food, water, temp. etc) we could pay $20 and ship them in a polystyrene box with an ice pack.

Brief calculations with the records of a collaborator's carefully managed colony suggest that half the animals could have been used (~$18k) and ~$10k saved in specialist shipping costs. Multiplied up to all of biomedical animal research, ethically, and financially switching to ground squirrels is a no-brainer.

Making a standard mouse that can hibernate would be even better, but that's not possible right now, although a huge expansion of ground squirrel research would probably crack that in short order.

*The fact that mice develop obesity & diabetes-like pathology just from increasing the fat proportion (not amount, they're usually allowed to eat as much as they want) of their food has been a hugely wasteful red-herring in regards to its relevance to human diet/pathology. If you switch just the proportions in human (or pig) diet, it doesn't replicate. Mice are metabolically very different to humans, a day without food is a huge stress. They eat a TON more than us proportionally to keep warm.

bs0u0155, Apr 09 2024

13 lined ground squirrel https://en.wikipedi...ned_ground_squirrel
[bs0u0155, Apr 09 2024]

Already in use as an experimental model https://www.ncbi.nl...rticles/PMC3362150/
[bs0u0155, Apr 09 2024]


       [+] I like it, though I wonder if being able to hibernate means they're too different from other rodents to make good models?   

       But if that's not a problem, also consider the meadow jumping mouse. Smaller than squirrels and may need smaller habitats, less food. And lots of fun and exercise you can have chasing any that get loose - they can jump 12 feet.
a1, Apr 09 2024

       Sounds like you know your subject and you've put some thought into it so I'll defer to you and guess it's a good idea. [+]   

       Assuming this isn't a prank and there's no such thing as a 13 lined ground squirrel, in which case I'd leave the bun anyway, got me. Good one.
doctorremulac3, Apr 09 2024

       //Assuming this isn't a prank and there's no such thing as a 13 lined ground squirrel,//   

       It does exist <link> and is for many reasons a more convenient model than the Grizzly Bear.
bs0u0155, Apr 09 2024

       I've just read that when kept hibernating in the lab, the 4 Celsius habitat is call a "Hibernaculum" which is the best word I've learnt in months.
bs0u0155, Apr 09 2024

       I get it, based on "hibernate".   

       I'd replace it with "hibernateuclitorium", because if you read it carefully, I stuck a naughty word in there to be funny.*   

       *(I'm an idiot)
doctorremulac3, Apr 09 2024

       //ethically, and financially switching to ground squirrels is a no-brainer.//   

       Somewhere far away, the operator of a meat grinder looks up with furrowed brow.
pertinax, Apr 09 2024


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