A better understanding of gliding motility in parasitic species could lead to medicines that prevent disease. In diatoms, Matthew Heintzelman is driven by scientific curiosity.

Just as some animals hop while others run, fly or swim, individual cells have different ways of getting around. Sperm cells swim by waving a hair-like flagellum, while amoebas and white blood cells crawl along with a shape-shifting motion. Since the 1700s, people have also observed cells gliding through their environment with no obvious means of propulsion. With the help of modern molecular tools, Associate Professor of Biology Matthew Heintzelman is teasing apart the secret.

The single-celled parasites that cause malaria and toxoplasmosis glide; so do some diatoms, the algae famous for building ornate, microscopic glass shells. Thanks to work by Heintzelman and others, we now know that both groups use actin and myosin, the same types of proteins responsible for muscle contraction, to glide. Dozens of myosins exist in different cell types, and Heintzelman is figuring out which ones are responsible for diatom locomotion.

Using genetic manipulation, Heintzelman can alter the myosins in a diatom. Introducing defective parts of the protein or eliminating it altogether allows him to assess the effect on locomotion; attaching a green fluorescent protein to myosins allows him to see where in the cell they show up. Myosins involved in movement are found near the raphe, a thin slit through the glass shell that provides the diatom's only exposure to the outside world.

A better understanding of gliding motility in parasitic species could lead to medicines to prevent disease. In diatoms, Heintzelman is driven by scientific curiosity. "For me, it's really just unraveling the mystery of it," he says. "Yes, there are probably practical applications down the road, but my interest is trying to understand something that people have been observing for 300 years."

The biology department's new confocal microscope, purchased in 2009 with a National Science Foundation Major Research Instrumentation grant, will help Heintzelman's research by allowing him to pinpoint the locations of different myosins within diatom cells.

"That's the great thing about science," Heintzelman says. "I feel like a 12-year-old kid who has been given permission to touch everything and just explore."

Posted Sept. 20, 2010