Sea Lions Suffer

Since I frequent the same California beaches weekly, I can't help but keep tabs on the big things that wash up. The picture above is of a decaying sea lion. My friend pointed it out about a week before the photo was taken. At that point the animal was alive and exhibiting a behavior she called “the Stevie Wonder”. Swaying his head back and forth, it was clear the animal wasn't well.

These days, this isn't an unusual sight. There are many sick or decaying seals and sea lions on the beach. Many of them sway, wallow and make their way, eventually, back to “health”. The cause: domoic acid, a neurotoxic product of what's called an algal bloom. These harmful blooms are increasing and the marine mammals are suffering.

A report published in the Proceedings of The Royal Society B (February 2008) shows that domoic acid exposed sea lions are developing a chronic condition. Researchers from several agencies including California's Public Health and the National Oceans Services examined hundreds of sea lions suffering from domoic acid poisoning over the last ten years.

What they've noticed is that, aside from initial acute symptoms, the animals may develop a “chronic epileptic syndrome characterized by behavioral changes, seizures and atrophy of the hippocampal formation.” They become lazy, vomit and twitch.

The results section of the paper references specific cases of strange activities. “Abnormal behaviors included standing in atypical locations (sleeping in a public restroom, climbing onto police cars, found up to 100 miles inland in an artichoke field, car dealership or walking down the road).”

On the upside, the authors conclude that these sick animals may provide a good model for human epilepsy and also serve as a tell tale for dangerous seafood.

On the downside, as the algal booms increase, marine mammals are likely to suffer more. And if the upside is knowing when our food is bad, the obvious negative is the potential of domoic acid poisoning for you and me.

Goldstein, T., Mazet, J., Zabka, T., Langlois, G., Colegrove, K., Silver, M., Bargu, S., Van Dolah, F., Leighfield, T., Conrad, P., Barakos, J., Williams, D., Dennison, S., Haulena, M., Gulland, F. (2007). Novel symptomatology and changing epidemiology of domoic acid toxicosis in California sea lions (Zalophus californianus): an increasing risk to marine mammal health. Proceedings of the Royal Society B: Biological Sciences, 275(1632), 267-276. DOI: 10.1098/rspb.2007.1221

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