Primitive survivor of the seas surrenders slimy secrets.
The thin, eel-like creature known as a hagfish undoubtedly looks like an easy meal to a passing shark, but as soon as the larger animal's jaws clamp down, its mouth is suddenly filled with a tough, bulky slime that clogs its throat and gills. The hagfish, a primitive ancestor of modern fish, has been repelling predators of all sizes with this defence mechanism for hundreds of millions of years. Today, scientists are closing in on the biochemical mechanism that produces these slimy filaments, which we might be able to employ for our own purposes.
Douglas Fudge, who heads up the Comparative Biomaterials Lab at the University of Guelph, has long been fascinated by how quickly these animals can produce large amounts of this material. "Originally we were just looking at the biomechanics of the process," Fudge says. "When we realized how good the properties of the fibres were, it turned into a biomimetics project."
Each one of those fibres is the result of a cell rupturing and releasing a coiled-up thread, which emerges from its microscopic package to become a visible strand a micron in diameter and some 15 centimetres long. The hagfish can emit some 25,000 of these strands at once in rapid succession from different parts of its body. Fudge compares the structure of the fibres to spider silk, which contains layers of crystalline planes called beta sheets separated by soft rubbery bits. "We think that's really the key to the high strength," he says, referring to the weak hydrogen bonds between those planes that allow them to stretch without breaking, yielding tensile properties that put our best metal alloys to shame.
The key to synthesizing such materials may have come with fresh insights into how its raw materials take on a coherent form within the specialized cells of the hagfish's slime glands. Using a focused ion beam scanning electron microscope, Fudge and collaborators at University of California Los Angeles and University of Southern California were able to break down the dynamics of these cells as they mature. They developed a 3D model that captures the changes in size and position of the cell's interior components, which effectively outlines the steps in the assembly and organization of the thread that becomes a slime fibre. "I really feel like in the next few years we'll be able to take this process in vitro," says Fudge.
Caption: (L to R) University of Guelph researchers Atsuko Negishi, Tim Winegard and Douglas Fudge find hagfish biomimetics studies a slimy business.
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|Title Annotation:||MATERIALS SCIENCE|
|Publication:||Canadian Chemical News|
|Article Type:||Conference news|
|Date:||Sep 1, 2014|
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