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The Visible Cell

Posted: 03/15/2010

At first glance, some of the images are delicate and lacy—like ice crystals clinging to a window on a sub-zero day or the trim on an antique wedding gown.

Further examination makes clear that these photos are remarkably detailed and far more delicate than intricately knotted thread. They are some of the first images captured by Skidmore’s new Libra 120 transmission electron microscope (TEM), whose acquisition was supported by a $700,000 grant from the National Science Foundation (NSF).

Purchased last fall and installed over the midyear break, the new TEM is now up and running. Faculty who oversaw its installation include Professor of Biology David Domozych (shown seated at the TEM) and department colleague Marc Toso, associate director of the College’s Microscopy Imaging Center. Fully trained in the new tool’s bells and whistles, Domozych and Toso have enthusiastically settled in to discover for themselves how to enrich their research using the new instrument.

Considered state-of-the-art, the Libra 120 TEM allows for high-resolution imaging—magnification up to 600,000 times, electron tomography and 3D imaging, elemental analyses and digital image capture. Domozych calls it “the best biological electron microscope on the market today.”

Skidmore’s TEM will be used for detailed research involving the cell walls of green algae and higher plants, gregarine protists, bacteria, and fruit flies, and for courses spanning biology, neuroscience, chemistry, geosciences, and physics. In addition, researchers from Albany Medical College (which does not have this instrumentation) will be allowed to use the equipment for their projects, which may open the door for Skidmore students who wish to partner with the bio-medical researchers at Albany Med.

Early images taken by Tosco and Domozych are featured in this portfolio. In their exploration of the green alga Penium, they captured the alga’s Golgi body (G) secreting extracellular polysaccharides; the chloroplasts (Ch) and mitochondria (M) are also visible. The Golgi body is an action-packed cell site: it’s where the polysaccharides and protein are packaged and shipped to the cell surface.

Several images show the finger-like cell membrane folds of a gregarine protist. From this perspective, it seems hard to believe that these primitive organisms are responsible for multiple diseases in humans and animals.

Penium also is shown in cross-section, a circular form in stunning detail, containing star-shaped chloroplast lobes that enclose valleys of cytoplasm and a large pyrenoid in the center of the image. This is the location of carbon fixation during photosynthesis.

In greater detail, another Penium image depicts the peripheral cytoplasm of the alga. This zone is dominated by the large, lobed chloroplast (Ch). In the surrounding lobes of cytoplasm reside distinct vacuoles (v). The cell wall (CW) and extracellular polymeric substance (EPS) are found on the cell surface.

The image of what appears to be a smiley-faced balloon is actually a viral particle.

An additional image shows the extensive polysaccharide sheath of the alga Chlorokybus. This sheath most likely protects the organism from water loss and pathogen attack.

There is also the plasmodesmata (arrow) of the cell wall (CW) of the alga Chara. The plasmodesmata are the channels that connect adjacent plant cells.

Domozych has been studying Penium for a number of years. “It’s on its way to being considered a ‘model’ organism, and provides a great tool for elucidating the basic cell biology, evolution, and molecular biology of green plants,” he explained. He’s about to begin a two-year study in which he hopes to learn more about Penium's value as a unicellular system for genetic transformation. Findings could have application for the food and pharmaceutical industries. Four Skidmore students will assist with the research, which is supported by a separate NSF grant totaling $232,000.