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BIOLOGY

Key Components of Insect Flight

Rensselaer researchers have discovered a key molecular mechanism that allows tiny flies to whirl their wings at a rate of up to 1,000 times per second. Reported in the Proceedings of the National Academy of Sciences (PNAS), the findings will help scientists gain a better understanding of how chemical energy is converted into muscle movements, such as the human heart muscle pumping blood. The research could lead to novel insights into heart disease, and might ultimately serve in the development of gene therapies targeted toward correcting mutations in proteins that detrimentally alter the speed at which heart muscle fibers contract.

The research is focused on a key component of muscle called myosin, the protein that powers muscle cell contraction. The Rensselaer team focused its efforts on the fruit fly and asked a basic question: Why are fast muscles fast and slow ones slow? They discovered that the reaction mechanism in insect flight muscle on the molecular level is different from how slower muscle types work.

“Most research has focused on slower muscle fibers in larger animals,” says Douglas Swank, assistant professor of biology and lead author of the paper. “By investigating the fastest known muscle type, the mechanisms that differentiate fast and slow muscle fiber types are more readily apparent.”

In general, myosin breaks down adenosine triphosphate (ATP), the chemical fuel consumed by muscles, and converts it into force and motion. To do this, myosin splits ATP into two compounds, adenine diphosphate (ADP) and phosphate. Each compound is released from myosin at different rates.

In slow-muscle contraction, ADP release is the slowest step of the reaction, but in the fastest muscle fibers, Swank’s team has discovered that phosphate release is the slowest step of the reaction.

The project is supported by a three-year $240,000 grant from the National Institutes of Health and a four-year $260,000 grant from the American Heart Association. The Rensselaer team is conducting this research in conjunction with scientists from the University of Vermont.

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