Guelph lab discovers the recipe for slime hey don’t look like much, resting at the bottom of a water-filled plastic pail like discarded lengths of grey-brown garden hose. But there’s more to those hagfish than that, says U of G biologist Doug Fudge. Provoke those garden hoses and they’ll produce a bucketful of gelatinous goop designed to ward off predators. In his science complex lab, Fudge and his collaborators are studying the mechanical properties of the slime for possible applications in everything from human health to structural mechanics. He cautions that any possible applications are a long way off. But this is where innovation starts, he says — with those unassuming-looking creatures and the scientist’s curiosity. For Fudge, that curiosity was sparked while he was studying biology at Cornell University in the early 1990s. That’s where he became acquainted with hagfish, a cousin of lampreys that oozes copious amounts of slime within seconds. Hagfish secrete the viscous stuff through glands running down both sides of their tubelike bodies. See it happen once and you won’t forget it, he says: “I’ve never seen anyone who’s not impressed.” Slime is believed to gum up predators’ respiratory systems, effectively choking them. In one PhD experiment at the University of British Columbia, Fudge and other researchers used a fish head model to show how water flowing over slimed-up gills slowed to a trickle. Since then, he’s been learning more about how the creatures produce slime and just what the material is made of. Earlier this year, that work was the subject of two papers published by Fudge and his Guelph collaborators in the Journal of Experimental Biology. Mixing and mucous are key. Lab tests at
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Guelph found that slime largely consists of coiled bundles — or skeins — of protein fibres along with vesicles containing mucous. Mixing the vesicles in water makes the mucous strands stretch, in turn causing the skeins to rapidly unravel in what he calls a “magical transition” and trap large volumes of seawater. But you need more than water. In the creatures’ marine home on the Atlantic or Pacific coast, it’s the agitation of the mixing that causes the thread skeins to uncoil and attract the mucous released from ruptured vesicles. In his lab, Fudge and undergrad student Tim Winegard made special glass chambers and used fluorescent dyes to capture the action under the microscope. Fudge believes there may be a way to mimic the process in certain industrial applications involving transmission of hydrodynamic forces on a small scale. In 2005, he and his UBC collaborators were awarded a patent for making silk-like fibres using intermediate filaments like the ones in hagfish slime. Their goal is to produce ultra-light fibres with the strength of steel. Fudge published a second paper this year that describes the contents of the slime, particularly large amounts of methylamines as well as various ions.The researchers had thought that the methylamines helped to stabilize the mucous vesicles inside the slime glands.The same substance helps sharks prevent loss of body fluids to seawater. “We expected to see methylamines were good at preventing vesicle rupture,” says Fudge, who worked with Julia Herr, a 2009 Guelph graduate now working on her master’s degree in his biomaterials lab. But more tests in special chambers found that these organic compounds failed to stop vesicles from bursting. “That was really surprising to us; we still don’t understand it.” He thinks the chemical environment or