”Prior to the invention of the microscope 400 years ago,there was no way to confirm the theory that illness is caused by viruses, bacteria, and other foreign invaders rather than by evil spirits. Today a simple optical microscope, not too different from the earliest prototype, sheds light on the microbes that make people sick and helps doctors prescribe appropriate treatments. Beyond bacteria, there are wonderful details of life millions of times smaller than the naked eye can see—tiny fibers attached to the lens of a human eye, the innards of an infinitesimal sea creature, the subtle ways in which a ball of cells morphs into a baby chick. These are all details that help scientists throughout the University of Miami unearth new knowledge—details of a magnificent universe that would be invisible without modern microscopy.

Horn of Plenty

When you move your leg, motor neurons in the ventral horn of the spinal cord receive the signal from your brain and prompt your leg muscles to contract. Using confocal microscopy, senior research associate George Lotocki, Ph.D. ’03, and postdoc Juan Pablo de Rivero Vaccari, Ph.D. ’06, at The Miami Project To Cure Paralysis in the Miller School ofMedicine captured this elaborate picture of trauma in the ventral horn of a rat’s spinal cord. The orange area is the epicenter of the trauma, which is most likely where bleeding caused immediate cell death. “If cells areirreversibly injured by mechanical traumaand die, there’s nothing we can do,” Lotocki explains. “But if some cells have a delayed death, we might be able to find ways of preserving them.” The green streaks represent activity of astrocytes, or cells that surround neurons and help regulate the chemical environment. The blue dots are cell nuclei, and the red dots are proteins that may play a role in cell death. This study is among a large body of work on spinal cord injury conducted in the labs of W. Dalton Dietrich, scientific director of The Miami Project, and Robert Keane, associate professor of physiologyand biophysics.

The World in a Grain of Sand

“To see the world in a grain of sand” is more than a line penned by poet William Blake; it’s modus operandi for Pamela Reid, Ph.D. ’85. Assistant professor of marine geology and geophysics at the Rosenstiel School of Marine and Atmospheric Science, Reid is leading an international team of investigators who study reefs formed by microorganisms instead of coral. These microorganisms bind sand grains together and induce precipitation of calcium carbonate to form mounds of limestone. Called either stromatolites or thrombolites depending upon their structure, they are living examples of Earth’s earliest reefs and reveal important information about the development of our planet. This confocal photomicrograph shows a vertical section through the top of a thrombolite from Highborne Cay, The Bahamas. The large green oval is a sand grain infested with coccoid cyano-bacteria (yellow dots); the red spaghetti-like strands are filamentous cyanobacteria.

Out on a Limb

What looks like a spacecraft covered in bubble wrap is actually the limb of a chick embryo in its earliest stages of development. According to Kathryn Tosney, chair of the Department of Biology in the College of Arts and Sciences, “The embryonic limb of vertebrates emerges as a tiny bud and is sculpted into its final form through interactions among cells.” Tosney took this picture to study what happens during this process, paying close attention to the “apical ectodermal ridge,” which is the thick ridge running from left to right in this scanning electron micrograph. Scientists have identified molecules in the ridge that guide limb development by signaling interactions among nearby cells. “When these interactions go awry in humans, babies are born with deformities such as truncated limbs or extra digits,” she explains. This is what happens in polydactyl cats. “These cats have more than five toes; they are quite good mousers!”

The Anemone Within

It’s hard to believe this simple larva will blossom into a sea anemone, the colorful creature whose lush tentacles sway in the underwater current like petals in a breeze. Using laser scanning confocal microscopy, associate professor of biology AthulaWikramanayake studies how primary germ (tissue) layers develop in animal embryos. The sea anemone has two germ layers instead of three, as in humans and other more complex animals. This makes the anemone an ideal evolutionary model. The red speckles in this image are the nuclei of cells that have differentiated to form the gut (endoderm) on the inside and the skin (ectoderm) on the outside. “These animals were among the first to have a gut,” Wikramanayake says. “We want to know how it made the first decision to form a gut.” To find the answer, his team manipulates various genes in the embryo, then studies what happens.

That Look in Your Eyes

Even if you’ve had 20/20 vision your entire life, you’ll most likely need reading glasses once you reach middle age thanks to presbyopia, the age-related loss of the eye’s ability to focus on near objects. “Understanding the mechanisms of presbyopia is listed as one of the priorities of the NIH’s National Eye Institute,” says Fabrice Manns, Ph.D. ’96, associate professor of biomedical engineering in the College of Engineering and codirector with Jean-Marie Parel of the Ophthalmic Biophysics Center at the Bascom Palmer Eye Institute. Manns, Parel, and colleagues were the first to use an environmental scanning electron microscope to show how tiny fibers called zonules attach to the lens of the eye. Zonules play a pivotal role in the eye’s ability to change focus and could be a factor in presbyopia. This image—which shows the stringy zonules between the lens and ciliary muscle—was part of a study funded by the NIH and the Vision Cooperative Research Centre in Australia.

Finding a Looking Glass

With a price tag starting at about $100,000, electron microscopes are far from ubiquitous. Students and faculty on the Coral Gables campus have access toatransmission electron microscope (used for sectional images) and a scanning electron microscope (used for 3-D images) in the Dauer Electron Microscopy Laboratory, located in the basement of the Cox Science Building. The lab also hosts classes for aspiring scientists on the art of electron microscopy. Another resource on the Coral Gables campus is the Center for Advanced Microscopy, housed in the Department of Chemistry. Among its equipment is an environmental scanning electron microscope, which, unlike conventional electron microscopes, can image wet specimens. Under the direction of Patricia Blackwelder since 1985, thecenter serves graduate students and faculty, as well as researchers outside of the University.Many research labs at the Miller School of Medicine have their own state-of-the-art machinery, including electron microscopes and confocal microscopes.

The Electron Age

Microscopes have come a long way since the late 1500s, when Dutch lens grinders Hans and Zacharias Janssen first put two lenses together in a tube. This was the precursor to today’s optical microscopes, which use diffracted light to produce an image. But most optical microscopes cannot furnish quality magnifications greater than 2,000 times because of the size of light-particle wavelengths. The wavelengths electrons produce are much smaller. Electron microscopes, which use a beam of electrons instead of light tocapture and stamp images onto the field, can obtain magnifications in the millions and produce sharp three-dimensional images. Many researchers also use confocal microscopes, which use light but are better than conventional optical microscopes for thick specimens. They use spatial filtering to eliminate flare and can collect serial optical sections to produce high-quality three-dimensional images.