Rotten Eggs

The other day I discovered our chicken's hidden nest with under the oak tree in the front yard. As someone with little chicken experience, I was inclined to immediately toss all twelve of them. The newest addition had to be at least a week old. For reasons I still don't understand, I was a bit squeamish about the whole thing. Determining that the feelings were irrational, I sent my four year old daughter to collect the eggs and called my husband for consult. My optimist husband, practical regarding such matters, gave me a quick biology lesson, “The bad ones will float.”

They float because with time, they dry leaving an air bubble. In our case, two of the eggs sunk down to the bottom of the bowl, eight stood on their end and two bobbed to the top. The optimist assured me that the eight eggs may not be bad, “You have to smell them.”

While I've never smelled an actual rotten egg, I know it's bad. And I wasn't about to risk nausea or illness to test the limits of my sensitive detection system. I'd had enough of the experiment and gave the girl child permission to throw the bowl of ten into the compost pile.

All the while, a mental image of one sulfur and two hydrogen atoms was bobbing around in my head. Hydrogen sulfide is a bacterial byproduct -a gas. I thought about what receptors the small molecule bind to and as always I like to reflect about its affect in the brain.

Too much of the gas is poisonous. It passes through cell membranes and shuts down cellular metabolism -in the lungs and in the brain. The toxicity reported is comparable to cyanide.

But hydrogen sulfide is also produced in our own tissues (independent of bacterial infection) as a part of our normal biology. The gas, termed gasotransmitter, is a neurotransmitter and represents a whole subfield of neuroscience. It is involved in maintaining the tone of blood vessels, the transmission of signals between brain cells and even insulin secretion.

Ironically, the primary characterized target of the gas is the molecule that I wrote my dissertation on, a potassium channel expressed in the brain, heart, and blood vessels.

My daughter hesitates before tossing the eggs “why can't we eat them?” she asks. “Because they might be stinky,” I answer saving the lecture on the potential role that hydrogen sulfide plays on the macromolecules in her brain.

Related reviews:
Leffer et al. 2006
Wang 2002