Group Looks at Genetics to Categorize Nematodes

Shahin Islam '12, Suman Sarker '11 and Barsha Baral '13.
Shahin Islam '12, Suman Sarker '11 and Barsha Baral '13.
Fever, coughing, vomiting, diarrhea: all of these are symptoms of parasite infestation. Nematodes are one of the most common types of human, animal and plant parasites. Not all nematodes are parasitic and not all parasites are nematodes, but these microscopic creatures are part of one of the most diverse phyla on the planet. Nematodes are not only diverse (over 28,000 species have been identified, 16,000 of which are parasitic), but are notoriously difficult to distinguish between species. Scientists have spent a lot of time attempting to place nematodes in their phylogenetic tree, but most of this categorization is based on morphological data, not genetics. Suman Sarker ’11, Barsha Baral ’13 and Shahin Islam ’12 working under Assistant Professor of Biology Wei-Jen Chang and Visiting Assistant Professor of Biology Ashleigh Smythe, are looking at genetics to more thoroughly categorize nematodes.

Although there are thousands of species of nematodes, only 14 species have been fully sequenced. When looking at the nematode genetics, the team is in search of their genetic Holy Grail: a universal marker—a common genetic pattern that runs through all fourteen species. Universal markers have been found in many other species—including humans—but nematodes have been neglected because they are so incredibly diverse. Although the difference between two worms may not seem like much to the average person, the difference is as great as that between a lion and tiger to a nematologist, Sarker, the team’s leader, said. The team is looking at ribosomal proteins for their genetic source, as ribosomal proteins are often well conserved. After poring over thousands of base pairs in search of a pattern, the team will choose a promising pattern to amplify using a PCR (polymerase chain reaction).

But the likelihood of finding a definite pattern on such a small scale is almost impossible to tell. “The likelihood could be probable to none,” Sarker said. “If we pick a sequence that’s well-conserved, the likelihood is good. But little differences [between the species’ genes] will speak volumes about their mutations and genetic history. This is very promising research, and if we do find something it will mean a lot to the world of nematology.”

Although only a rising sophomore, Baral knew long ago that she was interested in genetics. As a child in her native Nepal, Baral remembers seeing a girl who was completely covered in hair, a characteristic that most people thought of as a curse. “I saw these fascinating mutations that weren’t considered [scientific] because we didn’t have the technology,” Baral said. Intrigued by the relationship between science and superstition, Baral plans to immerse herself more deeply in the study of genetics in the future.

Sarker became involved in this project with Professor Chang three years ago. One day, Chang was lecturing on eukaryogenesis, or the beginning of eukaryotic cells. Sarker was frustrated because of the lack of a definite answer, and didn’t agree with the current leading theory. “I was kind of naïve in wanting to [do research and] solve it, but Chang thought it was funny and let me,” Sarker said. Although he has yet to solve this central mystery, Sarker has become increasingly well versed in bioinformatics and computer-based analyses. But the experience taught him a valuable lesson: “With regard to the material in textbooks, there’s a reason everything is cited. Research opens you up to challenge it; you’re supposed to know, understand and challenge the information presented,” he said.

Baral graduated from Grover Cleveland High School in Ridgewood, NY, Sarker from Manhattan Center for Science and Mathematics in New York City, and Islam from New Explorations into Science Technology and Math, also in New York City.
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