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12 December 2013 1:00 pm ,
Vol. 342 ,
Stefan Behnisch has won awards for designing science labs and other buildings that are smart, sustainable, and...
The iconic 125-year-old Lick Observatory on Mount Hamilton near San Jose, California, is facing the threat of closure...
Recent results from the Curiosity Mars rover have helped scientists formulate a plan for the next phase of its mission...
A new, remarkably powerful drug that cripples the hepatitis C virus (HCV) came to market last week, but it sells for $...
In pretoothbrush populations, gumlines would often be marred by a thick, visible crust of calcium phosphate, food...
Evolutionary biologists have long studied how the Mexican tetra, a drab fish that lives in rivers and creeks but has...
Victorian astronomers spent countless hours laboriously charting the positions of stars in the sky. Such sky mapping,...
In an ambitious project to study 1000 years of sickness and health, researchers are excavating the graveyard of the now...
- 12 December 2013 1:00 pm , Vol. 342 , #6164
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Video: How Cucumber Tendrils Curl
30 August 2012 2:00 pm
In 1865, Charles Darwin noted that the spiraling tendrils of the cucumber plant allow it to act in un-plantlike ways. By reaching for and grasping a support, then hoisting it toward the sun, tendrils allow the plant to move. Once tethered, the tendrils coil into a helix, shown in this video. Darwin theorized that the spiral acts like a spring, but noticed that unlike a classic spring, which curls in one direction only, cucumber tendrils wind in opposite directions from the tethered ends, forming a kink in the middle. Now, a team of scientists has figured out just how, and why, the cucumber tendril coils in this fashion. By observing the tendrils' formation and mimicking their structure with mechanical and mathematical models, the researchers found that after the tendril grasps its support, a thin, two-layer ribbon of gelatinous cells shrink on one side as they lose moisture, but not on the other. This asymmetric contraction causes the fiber to wind in opposite directions, creating a spring that may stabilize the plant against large disturbances while permitting it to gently move with small forces, like a gentle breeze. When pulled from either side, the fiber does not unwind like a normal spring, but actually winds tighter. Young, moist tendrils do not tend to overwind, the researchers report online today in Science, but mature, dry tendrils do—helping to explain how delicate tendrils gradually stiffen to support a vine laden with cucumbers.
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