The Do-Nothing Killer

(originally posted September 20, 2011)

The Nature Geek has a guest blogger today, which is me, Mr. Nature Geek. I know some of my antics (mishaps even?) have appeared in this blog before so I figured I should finally tell a story of my own. It’s about a lowly plant:

Imagine you’re doing what you do every day, maybe chatting with a co-worker at work. And then all of a sudden…a tiny bit of dust falls from the ceiling lands on your shoulder. Just dust. No problem! Except for the fact that the coworker you were just talking to pointed at you, went bug-eyed and tore off down the hall screaming something about a hideous monster that was going to eat everybody alive. A quick check in the bathroom mirror reveals nothing amiss, though exiting reveals that the office is deserted. As you head outside armed men flood the street and rush towards you, brandishing clubs, torches, and pitchforks, screaming “KILL IT!”

Now, before things get messy and not-G rated, we’ll end that story just by saying it ends not so well. But what kind of story is that? It didn’t have much plant life, but it is the story of what makes poison ivy “poison”. So what is really happening? Bear with me as I geek out.

This story starts with my “favorite” plant, poison ivy. Damaging a leaf releases sap full of a type of molecule called urushiol. These little monsters are oil-like, and so can easily penetrate your skin, walking right through the castle’s walls. One finds a random protein molecule on a cell (that cell is you, by the way) and bonds tightly to it. And then, (dramatic pause), it just sits there and does nothing. The cell keeps living happily. No explosion. No jolt of lightning. Just a little dust particle sitting on the shoulder of some cell and doing nothing.

Now what? That urushiol molecule keeps doing nothing. But other cells, part of your immune system, detect that do-nothing molecule on you and pretty much go bug-eyed and run screaming, just like that co-worker. That tiny little urushiol molecule makes them think you might be a brain-eating zombie, or worse, a virus infected cell. Other well-armed members of the immune system respond to that call (cue angry townsfolk) and flatten the place with you, a poor innocent cell, included.

As a real person however, you see the destruction in the form of blisters, redness, swelling, and itching. So the next time you wonder if that patch of green you just walked through was poison ivy, think of that story of an innocent cell and the "killer" molecule that does nothing. Just as every plant and animal has its own story, the molecules they use each have their own.