1 .
Directions: Fill in each blank with a proper word chosen from the box. Each word can be used only once.
Note that there is one word more than you need.
A. chaos B. consume C. plentiful D. discharge E. evolutionarily F. extent
G. freeze H. mechanism I. novel J. subsequently K. unstable |
Science in Images
Oyster mushrooms feature in cuisines around the world, but they should be off the menu for hungry worms -- which these delicious mushrooms will kill and eat. Now researchers finally know how they do it.
A study published in Science Advances details how oyster mushrooms use a particular poisonous substance to freeze and get rid of mushroom-eating roundworms called nematodes (线虫). The mushrooms, which grow on nutrient-poor dead wood, then 1 the worms for nutrition.
“Nematodes happen to be the most 2 animals these mushrooms encounter. So I think, 3 , this cross-kingdom interaction is very interesting,” says study senior author.
The study team of geneticists, biochemists and biologists had previously found that oyster mushrooms release an unidentified poisonous substance that will somehow 4 the worms within minutes and cause a chemical element to flow into their cells, killing them. This 5 differs from those used by other meat-eating mushrooms and could be unique to oyster mushrooms.
For their new work, the researchers grew and analyzed samples of the mushroom’s tissue, finding no noticeable poison even when they broke it up. They reasoned that whatever was killing the worms must be a kind of 6 compound that disappears into air when disturbed. When they damaged the oyster mushroom tissue again and 7 analyzed the nearby air, they finally found a nerve gas that turned out to be contained with tiny, special-shaped structures on the mushroom surface. When nematodes touch the mushrooms, these structures 8 their gas, disturbing the worms’ cell walls to cause immobility and death. The worm is then digested by the mushrooms.
Before this study, “we underestimated the 9 to which wild mushrooms defend against or consume nematodes,” notes Nick Talbot, a geneticist at Sainsbury Laboratory in Norwich, England. The study demonstrates “a very 10 approach,” he adds. “These organisms are really difficult to work on, and Dr. Hsueh is showing that you can do some really amazing work with them.”
