Text B. Seedy but Speedy: Fungus Spews Spores at 55 Mph

By Susannah F. Locke

In a finding that could help control harmful fungus, researchers have discovered a high-speed mechanism the germs use to project their spores into the air. Scientists from Miami University (M.U.) in Oxford, Ohio, and the College of Mount St. Joseph in Cincinnati report in the journal PLoS ONE that fungi may be one of the fastest land species, clocking speeds of up to 55 miles (88 kilometers) per hour and producing accelerations 180,000 times greater than gravity.

Fungi are the most common crop pathogens in the world. Most are fairly harmless to people, although like other allergens they sometimes exacerbate allergies and asthma. But certain varieties such as Stachybotrys chartarum, commonly referred to as black mold, that thrive in damp places like basements may also infect the lungs of people who have compromised immune systems or chronic bronchitis. Biologists once believed that mild air currents were enough to release fungi's spores, but are increasingly finding that molds employ elaborate methods to spew their seeds away from the nest. Using ultrahigh-speed video, the researchers calculated that some fungi use their own natural water pressure like squirt guns to eject their spores.

Lead study author Nicholas Money, a fungus biologist at M.U., studied fungi that grow on cow patties and other herbivore dung. These species play a critical role in the ecosystem by breaking down waste to recycle its nutrients into the soil. The fungi project their spores away from the resident dung because cows will not eat near feces. By shooting them up to eight feet (2.5 meters) away, a grazing animal will be more inclined to eat them, thereby spreading the fungal spawn via its own manure.

The research video camera shot 250,000 frames per second to capture fungi spurting their spores into the air, trailing glistening liquid behind them. The researchers used the video to clock the spores speeding along at 55 mph. The team also identified how several fungi build up water pressure to power a spore launch. First, the fungi accumulate sugars and other small molecules in their cells, which, in turn, brings in more water. Targeting the first step of this process could be a key to developing new fungicides. "By understanding the basic mechanism," he says, "you might find ways to remediate a mold-damaged home." (From Scientific American Online, September 17, 2008)

Exercise 4. Answer the following questions using the information from the texts:

1. What animal is generally considered the biggest organism on earth?

2. What extraordinary characteristics does the discovered Armillaria ostoyae fungus possess?

3. Why is Armillaria ostoyae characterized as a pathogenic fungus?

4. What conditions allowed the fungus to grow to such enormous size?

5. How can scientists distinguish an individual from a group of closely related siblings?

6. What effect do fungi produce on people and the environment?

7. What mechanisms does Stachybotrys chartarum black mold use to spurt its spores into the air?

8. Why do fungi have to employ such complicated techniques?

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