Genetically Engineered Mouse is Not Scared of Cats 286
Gary writes "A team from the University of Tokyo has genetically engineered a mouse that does not fear cats. By tweaking genes to disable certain functions of the olfactory bulb (the area of the brain that receives information about smells directly from olfactory receptors in the nose) the researchers were able to create a 'fearless' mouse that does not try to flee when it smells cats, foxes and other predators. 'The research suggests that the mechanism by which mammals determine whether or not to fear another animal they smell -- and whether or not to flee -- is not a higher-order cerebral function. Instead, that decision is made based on a lower-order function that is hardwired into the neural circuitry of the olfactory bulb.'"
An example for non-hunters who may not know (Score:5, Informative)
The sense of smell is a big deal in the way predator and prey interact. For example, without a doubt the best way to get rid of the squirrels in your attic is to squirt just a small amount of fox urine fox urine [cabelas.com] up there. Just a few drops around your attic ladder opening will have those little farts on the run and gone within a day. Then plug up whatever holes originally allowed them to get up there and the problem is solved.
One caution: I've found that it only works once. If you don't seal up those holes, the squirrels come back and the second application doesn't work. Maybe you just need fresh urine. But no matter the reason, don't put off the soffet repairs (or whatever work you need to do) after scaring them away.
Re:Rodent diseases? (Score:1, Informative)
Toxoplasmosis [cdc.gov]
Re:An example for non-hunters who may not know (Score:3, Informative)
That being said, here's another caution. Don't open the bottle and stick it under your nose to see what it smells like. Curiosity in unavoidable, but hold the thing away from you and fan the fumes toward you to satisfy that curiosity. A full-blast snort of this stuff will make you retch.
Re:Rodent diseases? (Score:5, Informative)
"It has been found that the parasite has the ability to change the behavior of its host: infected rats and mice are less fearful of cats"
Re:Smell only? (Score:5, Informative)
If it does run, however, you can make a high percentage guess that it thinks that's its best defense in the situation, so you're pretty safe in chasing it...It's not going to fail at running, then turn around and bite your head off.
Wrong assumptions (Score:3, Informative)
1. First of all, you seem to assume that the gene that recognizes "cat smell" just appeared out of nowhere. That's not the case. Even one cell organism have various degrees of analyzing the chemistry around them, because that's such a damn useful signal. Primitive sea organisms had some kind of sense of smell long before they even evolved eyes. Move out of the water and even primitive insects have a lot of smell sensors on their antennae.
So by the time they evolved to a mouse, it _already_ had a very sophisticated sense of smell, and the brain power to process, analyze, categorize and react to smells.
2. Even being sensitive to a very specific cat protein, if they have such cells, is easily explainable by mutation. Binding to some other mollecule is what proteins _do_. There are thousands of enzymes in your body that, basically, interact with just a single chemical, repeatedly. That's how you can process fructose (corn syrup) into glucose: an enzyme just breaks one molecule after another.
Heck, you even have cells in your immune system which _deliberately_ mutate until they make a protein that can match another protein. There's an enzyme whose sole role is to junk a random codon (think: byte) of DNA, so the DNA repair mechanisms would kick in, and occasionally get it wrong. And given enough time eventually you end up with a gene, by sheer random chance, that exactly matches the capsid of a new virus or some membrane proteins of a new bacteria. Amazing (and amazingly inefficient, if some God designed it), but there you go: making a protein that matches another protein is nothing new.
So given billions of billions of individuals, over millions of years, it wouldn't be surprising at all if some mice accidentally evolved noses perfectly attuned to cats. It could even start with a mouse with allergy to, say, FEL-D1 (a protein all felines have, and which is triggers cat allergies in some people), and it ended up giving his kids an advantage. From there it could evolve from mere allergy to panic attack, because the more scared you are of a cat, the more survival chances you have.
3. It's all chemistry, and there aren't that many mediators that regulate the moods. Triggering, for example, a panic just involves giving the right chemical signal.
And in the case of mice and rats, it's just that. There is no higher logic circuit in deciding to run from a cat. The smell just literally gives them a severe, illogical panic attack. When they test anxiety medication on rats, it's quite common to use cat urine to give them a reflex panic attack, then see if your drug calms them down. The running away is just the result of that panic, nothing more.
So don't think there's some complex coding involved. Even a simple enzyme could do just that: process the protein or chemical specific to cats, into the chemical that puts the brain into panic mode.
Plus, the way proteins work is rarely orthogonal coded. A small change here, produces an unrelated effect there. Some circuit in the brain could have simply been accidentally mis-wired to relay the signal along the wrong path, or release the wrong mediator.
At any rate, so a proto-mouse got a severe panic attack at the smell of a proto-feline, just because of a mutation, and it ended up saving his/her life. Then the kids inherit it and are the ones who have less of a chance of getting eaten.
4. Precisely the fact that it _doesn't_ react to other predators, should probably tell you that there is no higher intelligence or design at work.
The mice simply evolved to deal with the _existing_ threats, not to be the thing that can universally deal with any imaginable carnivore. Threats that actually existed and killed some of the mice, were evolutionary pressures. The mice which could deal with them, were more likely to survive, so those genes got passed on. The threats that they didn't have to deal with, _weren't_ evolutionary pressures and made no difference. So if a mouse-e
Re:Several false assumptions, there. (Score:2, Informative)
so the first versions would maybe give the carrier a small edge, but over time said edge would become more and more weighted compared to others.
as for odors being similar, i would guess that say foxes and wolfs have a similar baseline smell, but with variations. same with cats, lions and pumas. it could be that the same genes that control how a animal looks, control its odor.
another question is, does gene sorting stop when a animal is born? or is there a continual sorting as the animal ages? as in, genes, who's cells gets used more, gets priority in the next generation?
Re:Smell only? (Score:3, Informative)
I usually think of it as a sort of "hunting practice"...My most domestic cats are usually pretty lax...They'll even let things get away, once they're bored...But that initial bit of, "Ha! Gotcha! Ooooh, you wanna get away, well okay... Ha! Gotcha!" is all about "I could kill you if I wanted to...Damn I'm good."
My best hunting cat...I never saw him play with anything. It was dead, or it was beneath his notice. He was kind of a "big game" cat though; rabbits, groundhogs, crows...If he ever killed mice, he didn't bother leaving a "trophy" as it were.
Re:Smell only? (Score:4, Informative)
And, that's why in survival training the tell you not to run from a bear. If the bear sees you run you trigger the predator response. So instead you talk to the bear and back away the way you came. Bears don't normally eat things that talk and move backwards so you probably won't get mistaken for food. The result is a bear that is some what confused as to how it should react... so you just might get away.
So I wonder if our brave mousy friends get treated with equal confusion by cats.