The food we eat may control our genes
“You are what you eat.” The old adage has for decades weighed on the minds of consumers who fret over responsible food choices. Yet what if it was literally true? What if material from our food actually made its way into the innermost control centers of our cells, taking charge of fundamental gene expression?
That is in fact what happens, according to a recent study of plant-animal microRNA transfer led by Chen-Yu Zhang of Nanjing University in China. MicroRNAs are short sequences of nucleotides—the building blocks of genetic material. Although microRNAs do not code for proteins, they prevent specific genes from giving rise to the proteins they encode. Blood samples from 21 volunteers were tested for the presence of microRNAs from crop plants, such as rice, wheat, potatoes and cabbage.
The results, published in the journal Cell Research, showed that the subjects’ bloodstream contained approximately 30 different microRNAs from commonly eaten plants. It appears that they can also alter cell function: a specific rice microRNA was shown to bind to and inhibit the activity of receptors controlling the removal of LDL—“bad” cholesterol—from the bloodstream. Like vitamins and minerals, microRNA may represent a previously unrecognized type of functional molecule obtained from food.
The revelation that plant microRNAs play a role in controlling human physiology highlights the fact that our bodies are highly integrated ecosystems. Zhang says the findings may also illuminate our understanding of co-evolution, a process in which genetic changes in one species trigger changes in another. For example, our ability to digest the lactose in milk after infancy arose after we domesticated cattle. Could the plants we cultivated have altered us as well? Zhang’s study is another reminder that nothing in nature exists in isolation.
Source of Information : Scientific American Magazine
Showing posts with label PHYSIOLOGY. Show all posts
Showing posts with label PHYSIOLOGY. Show all posts
Friday, May 18, 2012
Friday, March 23, 2012
Olympians of the Sky
Researchers unravel some long-standing mysteries of bar-headed geese, the world’s highest-flying birds
Climbers struggling the last few steps to the peak of Makalu in the Himalayas have long marveled at the sight of bar-headed geese flying high above to their winter refuge in India. The birds cruise at an altitude of 29,500 feet, nearly as high as commercial aircraft.
For years scientists believed that strong tailwinds and updrafts aided the geese on their journey. A team of researchers led by Charles Bishop of Bangor University in North Wales tested this theory by tracking more than a dozen bar-headed geese harnessed with small backpacks containing satellite transmitters that established their location, speed and altitude.
To their surprise, the researchers discovered that instead of flying in the early afternoon, when heat from the earth can create 12-mile-per-hour updrafts, bar-headed geese consistently fly at night or during early-morning hours, when there is actually a slight downdraft. In a paper published recently in the Proceedings of the National Academy of Sciences USA, the team theorizes that because air is cooler and denser at these times, it allows the geese to generate greater lift. Cooler air also helps to regulate body heat and contains more oxygen, enabling geese to fly even as the air thins at higher levels.
Bishop and his colleagues also were amazed to find that the geese cross the Himalayas in a single day, traveling 20,000 feet in seven to eight hours. To fly so far at such a great height, the barheaded geese must sustain a 10- to 20- fold increase in oxygen consumption. By comparison, lower-altitude birds such as the Canada goose cannot sustain resting levels of metabolism at 30,000 feet. Bigger wings, bigger lungs, a dense network of capillaries surrounding the flight muscle, and hemoglobin that more tightly binds oxygen to the lungs work together to sustain oxygen flow throughout the bird’s circulatory system, including its flight muscle. Improving the understanding of why tissues in bar-headed geese are so adept at taking up oxygen might elucidate human respiration as well.
Source of Information : Scientific American Magazine
Climbers struggling the last few steps to the peak of Makalu in the Himalayas have long marveled at the sight of bar-headed geese flying high above to their winter refuge in India. The birds cruise at an altitude of 29,500 feet, nearly as high as commercial aircraft.
For years scientists believed that strong tailwinds and updrafts aided the geese on their journey. A team of researchers led by Charles Bishop of Bangor University in North Wales tested this theory by tracking more than a dozen bar-headed geese harnessed with small backpacks containing satellite transmitters that established their location, speed and altitude.
To their surprise, the researchers discovered that instead of flying in the early afternoon, when heat from the earth can create 12-mile-per-hour updrafts, bar-headed geese consistently fly at night or during early-morning hours, when there is actually a slight downdraft. In a paper published recently in the Proceedings of the National Academy of Sciences USA, the team theorizes that because air is cooler and denser at these times, it allows the geese to generate greater lift. Cooler air also helps to regulate body heat and contains more oxygen, enabling geese to fly even as the air thins at higher levels.
Bishop and his colleagues also were amazed to find that the geese cross the Himalayas in a single day, traveling 20,000 feet in seven to eight hours. To fly so far at such a great height, the barheaded geese must sustain a 10- to 20- fold increase in oxygen consumption. By comparison, lower-altitude birds such as the Canada goose cannot sustain resting levels of metabolism at 30,000 feet. Bigger wings, bigger lungs, a dense network of capillaries surrounding the flight muscle, and hemoglobin that more tightly binds oxygen to the lungs work together to sustain oxygen flow throughout the bird’s circulatory system, including its flight muscle. Improving the understanding of why tissues in bar-headed geese are so adept at taking up oxygen might elucidate human respiration as well.
Source of Information : Scientific American Magazine
Tuesday, December 13, 2011
The Trouble with Armor
The steel plates worn by medieval soldiers may have led to their wearers’ demise
On August 13, 1415, the 27-year-old English king Henry V led his army into France. Within two months dysentery had killed perhaps a quarter of his men, while a French army four times its size blocked escape to Calais and across the English Channel. Winter approached; food grew scarce. Yet in one of the most remarkable upsets in military history, a force of fewer than 7,000 English soldiers— most of them lightly armed archers—repulsed 20,000 to 30,000 heavily armored French men-at-arms near the village of Agincourt, killing thousands. Shakespeare’s play Henry V attributed the victory to the power of Henry’s inspirational rhetoric; the renowned military historian John Keegan has credited the self-defeating crush of the French charge. But a study by exercise physiologists now suggests a new reason for the slaughter: suits of armor might not be all that great for fighting.
Researchers at the University of Leeds in England placed armor-clad volunteers on a treadmill and monitored their oxygen consumption. The armor commonly used in the 15th century weighed anywhere from 30 to 50 kilograms, spread from head to hand to toe. Because of the distributed mass, volunteers had to summon great effort to swing steel-plated legs through each stride. In addition, breastplates forced quick, shallow breaths. The researchers found that the suits of armor doubled volunteers’ metabolic requirements, compared with an increase of only about 70 percent for the same amount of weight carried in a backpack.
Of course, medieval battles did not happen on treadmills. The fields at Agincourt were thick with mud, having recently been plowed for winter wheat and soaked in a heavy October shower. The French charged across 300 yards of this slop, all while suffering fire from the English archers. Combine the effort required to run in armor with that needed to slog through mud, says Graham Askew, one of the study’s leaders, and you’d expect at least a fourfold increase in energy expenditure—enough, it seems, to change history.
Source of Information : Scientific American Magazine
On August 13, 1415, the 27-year-old English king Henry V led his army into France. Within two months dysentery had killed perhaps a quarter of his men, while a French army four times its size blocked escape to Calais and across the English Channel. Winter approached; food grew scarce. Yet in one of the most remarkable upsets in military history, a force of fewer than 7,000 English soldiers— most of them lightly armed archers—repulsed 20,000 to 30,000 heavily armored French men-at-arms near the village of Agincourt, killing thousands. Shakespeare’s play Henry V attributed the victory to the power of Henry’s inspirational rhetoric; the renowned military historian John Keegan has credited the self-defeating crush of the French charge. But a study by exercise physiologists now suggests a new reason for the slaughter: suits of armor might not be all that great for fighting.
Researchers at the University of Leeds in England placed armor-clad volunteers on a treadmill and monitored their oxygen consumption. The armor commonly used in the 15th century weighed anywhere from 30 to 50 kilograms, spread from head to hand to toe. Because of the distributed mass, volunteers had to summon great effort to swing steel-plated legs through each stride. In addition, breastplates forced quick, shallow breaths. The researchers found that the suits of armor doubled volunteers’ metabolic requirements, compared with an increase of only about 70 percent for the same amount of weight carried in a backpack.
Of course, medieval battles did not happen on treadmills. The fields at Agincourt were thick with mud, having recently been plowed for winter wheat and soaked in a heavy October shower. The French charged across 300 yards of this slop, all while suffering fire from the English archers. Combine the effort required to run in armor with that needed to slog through mud, says Graham Askew, one of the study’s leaders, and you’d expect at least a fourfold increase in energy expenditure—enough, it seems, to change history.
Source of Information : Scientific American Magazine
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