ASU Research E-Magazine: Confocal Microscopy

Lasers have long been on the cutting edge of technology in music, communications, and medical science. Now, they are making important contributions for researchers who study microscopic worlds.

Richard Satterlie knows the usefulness of laser technology. Lasers helped him find a new cell in an organism he has been studying for more than a decade. The organism, known as Clione limacina, is an inch-long, almost transparent bag of seawater with devil’s horns and angel’s wings that beat continuously. A nasty little carnivore, Clione is a shell-less mollusc that lives at depths of up to 100 meters in cold northern waters of the Pacific Ocean.

Satterlie discovered a cell—actually a pair of cells—that expresses the chemical serotonin, a neurohormone that acts on muscles and nerves. In the past, Satterlie had shown that such cells generate a beating of Clione’s wings and help it “fly” about in its aqueous environment.

Normally, Satterlie locates the nerve cells by tagging them with antibodies that are linked to fluorophores, compounds which fluoresce when illuminated with a certain wavelength of light.

“We’ve done this immunohistochemistry many times before using a standard fluorescent microscope,” Satterlie says. “We thought we had mapped out all of the cells that react to serotonin.”

But this time, Satterlie viewed Clione under the discriminating eye of ASU’s new laser confocal microscope, housed in the Goldwater Technology Center. The instrument sports fluorescent capabilities like that of a conventional microscope, which illuminates a fluorescently-labeled specimen and detects the fluorescent light it emits.

Most microscopes collect light from the whole sample, although only one part of the specimen is usually in focus at a time. Light arising from other planes of the sample usually impinge upon the focal point and somewhat distort the resulting image.

The confocal microscope, however, blocks out all light except that coming from the plane of focus. The researcher can then focus up and down within the sample, store virtually perfect images in the connected computer, and reassemble them into a three-dimensional reconstruction of a cell.

“We’re optically sectioning the specimen, not physically sectioning it,” explains Charles Kazilek, associate research professional in the department of zoology. Kazilek manages ASU’s Life Sciences Visualization Group, which oversees the confocal microscope along with other imaging instruments housed in the Goldwater Technology Center.

The result is a clearer, purer image comprised of anywhere from one to several hundred optical “slices” of a specimen. In Satterlie’s case, using the new technology meant finding a cell that was probably obscured by light from the cells in front of and behind it.

“We’re not sure exactly how the cell fits in with the other cells that influence acceleration in Clione,” Satterlie explains. With the help of the confocal microscope, he plans to find out.—Alana Mikkelsen