U of M Research Leads to Detailed Images of Cell Structure

Images may help scientists understand mutations that lead to disease

MINNEAPOLIS / ST. PAUL (Aug. 21, 2006)--Researchers at the University of Minnesota in collaboration with researchers in Boulder, Colo., have used specialized technology to get a detailed look at the structure of the flagellum, a tiny cellular machine that helps the cell move.

A better understanding of this structure will help scientists study mutations in flagellum that can lead toward infertility and other diseases.

The researchers used a high-resolution electron microscope to look at flagella from a species of algae that was embedded in ice. The cryotechnology allowed the scientists to view the samples as they would look in a functioning cell, with no staining or manipulation, at a very high resolution.  The samples were also tilted in the microscope so that the researchers could look at it from many angles and then reconstruct the structure in three dimensions.

“Visualizing how the different parts of the flagellum fit together will help us understand the structural basis for mutations that lead to infertility and other diseases,” said Mary Porter, professor of genetics, cell biology and development at the University of Minnesota Medical School.

Porter collaborated with researchers at the Boulder Laboratory for Three-Dimensional Microscopy, one of the few facilities in the country that has the technology to use cryo-electron microscopy to look at cell structure. Porter prepared the samples of both normal and mutant flagella, and the Boulder colleagues froze and preserved the structures for imaging in the cryo-electron microscope.

The flagella from single-celled algae serve as a good model for understanding how cilia and flagella in humans operate. “By understanding how the proteins that form the flagella work in these organisms, we can make inferences to how they work in humans,” Porter said.

The research is published in the Aug. 18, 2006 issue of Science.

Flagella are tiny tubular structures attached to the outer surface of the cells that have a whip-like movement, which allows the cells to move through fluid environments. The sperm tail is a common example of a flagellum. Closely related structures called cilia are also found on the surface on many tissues in the body.

Cilia and flagella are composed of more than 300 proteins that are meticulously arranged in a very ordered structure to help in cell signaling and motility, Porter said. Defects that affect motility can lead to infertility, chronic respiratory disease, and defects in embryonic development, while defects in the cell signaling can lead to problems such polycystic kidney disease, obesity disorders, and defects in limb development.

With the sophisticated images that the Boulder researchers captured, researchers will now be able to study the connections between the proteins that make up flagella and learn how they work together.

In the future, Porter said scientists may be able to use the same techniques to examine cilia and flagella from humans.

The Academic Health Center is home to the University of Minnesota’s six health professional schools and colleges as well as several health-related centers and institutes. Founded in 1851, the University is one of the oldest and largest land grant institutions in the country. The AHC prepares the new health professionals who improve the health of communities, discover and deliver new treatments and cures, and strengthen the health economy.

Contact: Sara E. Buss, Academic  Health Center, 612-624-2449
Liz Bryan, Academic Health Center, 612-624-5680