From Tiny to Spectacular
To the naked eye, a speck is just a speck. But when viewed through the College’s scanning electron microscope (SEM), a speck can become intricate and beautiful, resembling a star, a flower, a creature from a child’s book of fantasies.
More significantly for scientists, images produced by the SEM are extreme magnifications of some of earth’s smallest objects, and they help shed light on the foundations of life itself.
According to Biology Professor Peter Bradley, Ph.D., the SEM has unique capabilities for imaging biological systems. It can magnify objects up to 20,000 times, in contrast to the maximum resolution of 1,000 diameters provided by light microscopes. Additionally, the SEM produces clear images that are easy to print, making it an ideal tool for research and instruction.
“Most microscopes use light, and magnifications are achieved with lenses that magnify an image,” Bradley explains. “But electron microscopes use a stream of electrons [subatomic particles with a negative charge] focused electronically. The specimen is coated with gold, and the electrons bounce off the specimen and are collected to generate the image electronically.”
Students in Bradley’s Tissue Culture, Soil Biology, and Plant Sciences classes observe the results of this complex process firsthand, while some undergraduate students have used the instrument in independent study situations and graduate students have used it for research.
Eva Ikonomu ’07 and her sister Katerina Ikonomu ’07 - who both majored in biology and minored in chemistry - received training in using the SEM during an independent study project Bradley supervised. They were preparing for internships at the University of Massachusetts – both under the supervision of Assistant Professor of Biology Guillermo Paz-y-Mino C., Ph.D. - and were required to be familiar with the SEM.
Eva, who plans to go to dental school, says, “During my internship at UMass, I worked on a molecular biology project with Ph.D. and post-doctoral students in the Biochemistry and Pharmacology Department for six months.”
She was involved in an ongoing investigation into the relationship between nucleostemin and p53, two proteins that control cell growth. Results of the study could lead to new treatments for cancer.
Katerina, who plans to earn a Ph.D. in neuroscience, was an intern in the UMass Psychiatry Department. Her 12-month commitment involved working with graduate students and employees on an analysis of the interaction of BDNF - a neuro-growth factor - and micro RNA in normal and schizophrenic brains. “Micro RNA naturally decreases in normal teenagers and increases in schizophrenics,” she explains, “while BDNF increases in normal teenagers and decreases in schizophrenics.”
The research may ultimately lead to better treatments for and prevention of schizophrenia.
Although the SEM is widely used in medical research, it has numerous other applications. Adrienne Smyth M.S. ’06, an adjunct faculty member who worked as a molecular biologist for many years, relied on the SEM for her master’s thesis research at Poutwater Pond in Holden, Mass. The site, a National Natural Landmark and Massachusetts’ first Nature Preserve, is a sphagnum peat bog and pond where plant material has accumulated under acid conditions since the last retreat of the last Ice Age.
“The acidic environment acts as a preservative,” explains Smyth, who earned an M.S. in biotechnology. “Because of this, peat lands have attracted a lot of interest as a tool for understanding the impact of climate change. Dr. Bradley and I worked together for a year to create a high resolution visual documentation of the presence or absence of pollen, algae, and other life forms in the bog.”
Smyth and Bradley borrowed a Russian core borer from Harvard Forest and collected peat samples from the surface down to the underlying mineral material, a depth of more than 15 feet. A Faculty Mini-Grant paid for radiocarbon dates, which showed the bog to be about 8,500 years old.
Taking samples from various depths, Smyth separated pollen, algae and some animal microfossils from the organic material and examined them on the SEM. She identified many of the specimens and prepared a catalog of pollen and algae. She and Bradley also collected present-day pollen for use in the study.
Their findings show that the bog was a deep open water environment 8,500 years ago and that peat layers accumulated over subsequent wet and dry periods. Pollen grains from the 1600s suggest the presence of human activity in the area. “It is likely that Native Americans and colonists were aware of this site, and exploited its vegetation and surroundings,” Smyth observes.
“The SEM is ideal for species identification because it shows such detailed structure and fine sculpturing,” she continues. “The fine resolution enables you to see, for example, if what you’re looking at has 10 pores or 50 pores, which tells you if it’s one species or another.”
This is important, she explains, because “Abundance profiles of diatom [algae] communities permit interpretations of the past environmental history of the site, but most are not performed at a resolution to investigate diatom species differences. Diatom abundance data combined with high resolution species information may further contribute to our knowledge of past environmental history and aid our understanding of future challenges ahead.”
Study of Poutwater Bog and Pond is ongoing, Bradley points out, and involves a number of faculty members and students from WSC Biology and Chemistry Departments. For example, Biology Professor Ellen Fynan, Ph.D., and her students intend to continue to isolate and identify bacteria from the peat core. In addition, the antibiotic resistance of these organisms will be compared to that of organisms from other sources within the bog.
“We pride ourselves on having excellent labs with all of the courses for biology and biotechnology majors,” he says. “The SEM is one extra technique that enables students to explore life and all its manifestations on another level.”
Worcester Statement, fall 2007