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A grain of wild wheat comes fully equipped for its own propagation into planthood, including tools for drilling into the soil. It uses its two bristles, called awns, for this: In the dry daytime air, these bristles bend outwards. At night, dampened by the dew, they straighten. Over several days, this movement, similar to the swimming strokes of a frog, pushes the grain into the soil.
This discovery was made by scientists from the Max Planck Institute of Science in Germany. Weizmann Institute graduate Dr. Rivka Elbaum took part.
According to the researchers, a similar mechanism could use fluctuating humidity levels to drive micromachines.
Elbaum, currently a Humboldt fellow at Max Planck's Institute of Colloids and Interfaces explains: "The mechanism is similar to that with which pine cones open. The central area of the ridge functions like a muscle, bending and straightening the awns."
However, on its own, the muscle is not sufficient to make grains burrow into soil; that only happens with the help of the fine silica hairs on their outer side. The hairs act as barbs which we can also feel. If you run your finger along the awn away from the grain, the awn feels smooth; toward the grain, the barbs offer tangible resistance.
These tiny silica hairs prevent the awns from pushing themselves out of the soil when the bristles straighten during the night. They can only move into the earth, and thus push the grain a little deeper every night. The scientists discovered this by wrapping a grain of wheat and the lower section of its awns in a cloth. The silica hairs caught on the cloth. When the researchers alternately raised and lowered the humidity, the grain moved a little deeper into the cloth with every cycle. Domesticated wheat has lost the ability to perform this "trick."
"Wild wheat uses this mechanism to disperse itself," says Prof. Peter Fratzl, who headed the Max Planck research group. The seed uses its swimming movements to propel itself across the ground, as well as into the soil.
"We have already built simple machines and muscles modelled on the awn mechanism to convert variations in humidity to movement." After all, it is the heat of the sun that dries the air which the dew dampens during the night. Fratzl sees this as a potential contribution to renewable energy. "I'm fascinated by the possibility of converting solar energy to movement in this way."
RED PLUM TO COUNTERACT RED MEAT
The red-fleshed plum contains the highest levels of antioxidants among the fresh fruits sold in Israel, according to new research at the Volcani Institute at Beit Dagan. The research found that the levels of antioxidants in fresh red-flesh plums are three times as high as those in pomegranates, and five times higher than in red wine, apples or bananas. Eating one plum counters the oxidizing agents in a portion of red meat
Processing and cooking meat starts various oxidizing processes, which continue in the stomach as we digest our food. These processes produce highly active oxidizing agents and produce many cytotoxic compounds, some of which are absorbed into the blood and can damage the cardiovascular system.
In the research, conducted by Prof. Joseph Kanner from Volcani's department of food science, levels of oxidation caused by the digestion of red turkey meat in an artificial stomach medium were measured. Extracts from different fresh fruits were added to the simulated digestion and the effect on oxidation and antioxidant levels was measured for three hours.
The research revealed that red-flesh plums of the Red Heart family (cultivated and grown by Ben-Dor Fruits & Nurseries) top the charts with their exceptionally high levels of antioxidants. To maximize efficiency of the beneficial antioxidants, one should eat the fruit with the meal. In fact, eating one such plum during a meal counters the oxidizing effect of 200 grams of red meat.
Kanner has conducted several researches on Mediterranean diet and food oxidation in the human digestive system. In the early 90s, he attracted much interest when his research explained the "French paradox" - how it is that the rate of heart attacks in France is low despite a diet which includes high levels of animal fat. Kanner suggested that one possibility is the French custom of consuming red wine during meals.
BYE BYE, BEES
Honeybee colonies are being decimated across the US - a potential disaster for agriculture, since bees pollinate crops worth $14 billion each year. The precise cause remains elusive, but researchers are investigating all culprits from pathogens and pesticides to the nature of beekeeping. Bustling colonies each containing tens of thousands of bees in 22 states have emptied out in a matter of days.
"Imagine waking one morning to find 80% of the people in your community gone," says May Berenbaum of the University of Illinois.
There is no shortage of potential culprits; European honeybees make up the vast majority of commercial stocks in the US, and they are susceptible to myriad viral and fungal blights and two forms of parasitic mites, one of which wiped out about half of the American honeybee population in the 1980s.
But in this instance, the precise cause of the sudden decline, dubbed "colony collapse disorder" or CCD, remains elusive. The pattern of disappearance offers few clues, since CCD appears to be widespread and plagues non-migrating colonies as well as those that are moved from place to place to pollinate crops.
Despite the sketchy details, lawmakers have begun taking note of the industry's plight. The US Department of Agriculture is being asked to double its funding for the nation's four bee research labs.