Experimental Biology 2011, Washington, D.C., April 9–13
Color preferences of larval pests Insect larvae lack sophisticated eyes but do detect hues — and exhibit distinct color preferences. Vonnie Shields’ team at Towson University in Maryland reported April 12 on experiments putting larval Colorado potato beetles and gypsy moths on a treadmill. After being acclimated to darkness, the grubs or caterpillars were exposed to LED light in one or two colors and then were watched to see whether they stayed put or were attracted to a color. Beetle grubs wriggled to green, orange, yellow and white hues; gypsy moth caterpillars preferred those, except orange, plus red and ultraviolet wavelengths. Shields says such data could be used to design light-based bug traps for pests. —
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An omega-3 fat known as DHA (docosahexaenoic acid) appears to limit age-related mental decline. Karin Yurko-Mauro of DHA manufacturer Martek Biosciences Corp. in Columbia, Md., reported April 9 on a six-month study of 485 healthy adults, average age 70. Those who took 900 milligrams of DHA daily made fewer learning and memory errors than did participants who had gotten a 900-milligram mix of vegetable oils. DHA improved participants’ “cognitive age” from a presupplementation average of 72.6 years to a posttreatment score equivalent to 65.6 years. A second study failed to find similar benefits in Alzheimer’s patients given 2 grams of DHA daily for 18 months. —Janet Raloff
Blueberries take aim at body fat
Heart-healthy antioxidant compounds found in blueberries limit the buildup of fat in mouse cells. Many darkly hued fruits are rich in polyphenols, antioxidant compounds that have been linked to vascular health. Shiwani Moghe of Texas Women’s University in Denton reported April 10 finding that blueberries’ polyphenols not only fight the proliferation of fat-precursor cells but also limit the accumulation of fat droplets once fat cells do develop (by 27 to 73 percent, depending on the dose of polyphenols used). For these preliminary tests, her team incubated mouse cells for eight days with a natural mix of isolated berry polyphenols. Moghe says there’s no telling how much people might have to eat if they hoped to achieve a similar effect. —Janet Raloff
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Cutting canned goods’ salt
Cooks can easily remove a notable share of the salt in canned goods, David Haytowitz of the U.S. Department of Agriculture’s Beltsville Research Center in Maryland reported April 10. His group analyzed two store and two national brands of peas, green beans and sweet corn. Although canned veggies average 240 milligrams of sodium per 100 grams of food, some tins had far less — one just 2 milligrams per 100 grams, even though its label boasted 400 milligrams. Where measured levels were high, draining off the cans’ liquid contents dropped sodium levels 2 to 5 percent; rinsing drained veggies with 3.5 liters of water dropped sodium an additional 7 to 12 percent. —Janet Raloff
Distemper virus evolved from measles
Here’s a man-bites-dog story: Canine distemper may have originated in people. Researchers have long known that measles and distemper are caused by closely related viruses. Now veterinary pathologist Elizabeth Uhl of the University of Georgia and her colleagues say that the canine distemper virus evolved from measles. Distemper was first described in 1730 in Peru. But when Uhl examined skeletons from New World dogs that lived before European contact, she found no evidence of eroded tooth enamel, a hallmark of the disease. Distemper uses a version of the genetic code more similar to the one favored by human cells than to the dog pattern, the researchers reported April 10. That bias suggests that distemper is related to a virus that infects humans. Uhl and her colleagues speculate that distemper might have arisen when the Spaniards fed native people with measles to dogs. —Tina Hesman Saey
Artificial sweeteners fool pancreas
No-calorie sweeteners can fool the pancreas into releasing insulin. Scientists recently discovered that a protein that senses sweet taste on the tongue is also found on insulin-producing beta cells in the pancreas, where it triggers insulin release upon detecting glucose. Aspartame and sucralose both work similarly to glucose to cause insulin release, Ali Al-Saleh of Boston University School of Medicine and his colleagues reported April 10 in Washington, D.C., at the Experimental Biology meeting. On the other hand, big doses of saccharine blocked insulin release. But laboratory-grown cells bathed in low doses of saccharine released abundant insulin when the researchers added a bit of glucose. Artificial sweeteners may put pancreas cells under stress by causing insulin release when it’s not necessary, Al-Saleh says. —Tina Hesman Saey