gatechgirl

Well, the clues we really have about their behavior can probably mostly be gathered from their fossil remains, specifically skeletal fossils. Short arms, (relatively) large "hands" with three long claws, a funky second digit on their "feet", longish tail (relative to its body)... seemed about 30ish lbs..... Arboreal locomotion in extant animals is adapted to in a bunch of different ways. Suction or some other form of adhesion (like in frogs or something)... long arms (think monkeys)... small size (chipmunks, birds, snakes.. don't wanna break the branches I assume)... being able to grip or grasp with a hand (monkeys) or claw thing (like birds gripping a branch) or maybe a prehensile tail... maybe there's other examples of adaptions for arboreal locomotion that I can't think of right now. I feel like their funky claws and short arms were probably more for slashing at things, hunting, killing, all that stuff like maybe how Jurassic Park depicts it. But just because a feature doesn't seem specifically adapted to a certain function doesn't necessarily mean the animal is (well, was) completely incapable of said function, so perhaps it could still climb. After all, humans don't seem particularly well adapted for getting around in the water, but that doesn't stop Michael Phelps (now I'm imagining velociraptors competing in fanciful Olympic events like tree climbing... ) Maybe it had the bird-gripping-a-branch thing going for it, the whole modern bird thing you pointed out could mildly support that hypothesis. Perhaps its tail was flexible, prehensile-like (yet kinda doubtful). I just finished a really interesting terrestrial vertebrate class where we talked about things like this. Adaptions conferring to functions, being able to tell something about an animal based on what it looks well adapted for. Pretty interesting. But honestly, I'm just a lowly undergrad. These are simply my musings, definitely not fact.

I get that... but how does the body discriminate between disease-causing matter you put in your mouth (like typhoid antigen) versus something like food? Why don't antigenically intact macromolecules from food cause an immune reaction (well, they typically don't... food allergy I guess is the short-coming of this), and instead elicits an oral tolerance response, while the body knows for sure that other orally ingested antigens from things that are actually pathogenic and causes an immune response? How does it know the difference, whether to invoke oral tolerance or an immune response against whatever it is presented with?

I just finished the 4000 level immunology course at my university. I initially had no particular interest in immunology, but now I can't stop thinking about it! I have recently received several vaccinations in preparation for an upcoming trip to western Africa (I'll actually be working in an AIDS clinic, yet my question today doesn't have to do with how fascinating AIDS is with respect to immunology). Today, I started my oral typhoid vaccine, US Brand name Vivotif. I began wondering why this immunization was an oral immunization, while most are injections given in the arm. And then I remembered reading and listening to a lecture about mucosal immunity and oral tolerance... I can't help but think that oral vaccinations would elicit the wrong immune response. Wouldn't an antigen (I assume Vivotef is a non-virulent or inactive antigen) delivered orally elicit a weakened immune response upon re-exposure, rather than a heightened one as is being observed in the case of the oral typhoid vaccination? Could someone explain what is happening (or not happening) with oral vaccinations (especially with respect to oral tolerance)???