SCIENCE LAB SPECIAL : TOXIC BEHAVIOR

 

How a dining delight manages to satisfy its own appetite for flesh.

The oyster mushroom is a mild thing, a creamy-colored whorl of fungus that goes well with thyme sauteed in butter.

But among scientists who study mushrooms, it has earned a reputation for activities more sinister than fine dining. 

The oyster mushroom is a carnivore.

The mushroom's usual diet of damp logs is low in nitrogen. To get that essential element, it feeds on microscopic nematodes, a type of worm.

When a worm makes the mistake of passing over the fungus, the oyster mushroom paralyzes and kills it, using rootlike tendrils called hyphae to devour the animal's nitrogen-rich flesh.

In a paper published in the journal Science Advances, researchers reported that they had identified the toxin it uses to immobilize its prey.

To the scientists' surprise, it is a fairly common module, rather than an exotic, highly evolved substance. But to the hapless worms, it's deadly.

Outside the animal kingdom, Venus flytraps, pitcher plants and others are well known for their macabre meals.

But some fungi, too, have an appetite for flesh. It's not just the oyster mushroom, although that is the only carnivorous fungus you'll generally find in your grocery store.

Some fungi craft sticky nets laced with tempting scents to snare their prey. Some even release tiny sickle-shape spres that, when swallowed by a nematode, wreak havoc from within.

In the case of the oyster mushroom, worms that touch the fungus are paralyzed, and their cells fall apart as they succumb to the hyphae.

[Veronique Greenwood]