Harvard University - Department of Molecular & Cellular Biology


by Cathryn Delude

May 25th, 2011

In spring 2011, two graduate students in the Molecular and Cellular Biology department received prestigious awards.

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(L-R) Sharad Ramanathan and Hannah Shen

Hannah (Ching-Han) Shen, a second year graduate student in Sharad Ramanathan's lab, received a prestigious NSF Graduate Research Fellowship from the National Science Foundation. She will receive a three-year annual stipend of $30,000 along with a $10,500 cost of education allowance for tuition and fees, opportunities for international research and professional development, and the freedom to conduct her own research at any accredited U.S. institution of graduate education they choose. The NSF Graduate Research Fellowship Program (GRFP) recognizes and supports outstanding graduate students in NSF-supported science, technology, engineering, and mathematics disciplines who are pursuing research-based master's and doctoral degrees at accredited United States institutions. As the oldest graduate fellowship of its kind, the GRFP has a long history of selecting recipients who achieve high levels of success in their future academic and professional careers.

About the Research

Hannah Shen will use her NSF fellowship to answer some of life’s more intriguing questions. Why do we feel happy when eating delicious food? Why do we cry when watching sad movies? Certain brain areas are activated in certain circumstances, but scientists still cannot answer how exactly different brain states lead to distinct behaviors. Shen uses the nematode Caenorhabditis elegans to understand how the dynamics of neuronal activity can control different behaviors by perturbing the activity of specific neurons in a freely moving animal and then observing the behavioral changes after perturbation. She does this by using optogenetics, which involves inserting light-activated ion channels into neurons in the worm, and then exciting or inhibiting those neurons by shining light on them. She wanted to stimulate just a just a specific subset of neurons that she had engineered to express light-activated ion channels. But that was like trying to shoot a cockroach as opposed to an elephant, she says, requiring both super precision and speed. Luckily, Dr. Askin Kocabas, a post-doctoral researcher also in the Ramanathan lab, developed an optical set up that overcame that challenge. By using this method to express these light-activated channels in different sets of neurons, Shen can now study how the information coming from the sensory neurons is transmitted through the neural network. As an example of such study, she will dissect the dynamics of the neural circuit controlling the decision to turn left or right.

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Kevin Esvelt

Kevin Esvelt, an MCB graduate now at the Wyss Institute for Biologically Inspired Engineering at Harvard Medical School, received the 2011 Harold M. Weintraub Graduate Student Award from the Fred Hutchinson Cancer Research Center.  The award, which is presented to up to 12 graduate students a year, recognizes outstanding achievement during graduate studies in the biological sciences on the basis of the quality, originality, and significance of their work, as well as to represent a diverse range of research topics. Esvelt attended the presentation of the awards on May 6, 2011, at the Fred Hutchinson Cancer Center in Seattle, Washington. Awardees also participated in a scientific symposium honoring Hal Weintraub, a member of the Basic Sciences Division of Fred Hutchinson from 1978 until his death from cancer in 1995.

About the Research

Kevin Esvelt conducted the research honored by the Fred Hutchinson Cancer Research Center as a member of David Liu's lab in Chemistry and Chemical Biology, where he worked on directed evolution. Natural evolution is masterful at producing highly active genes, but the process is slow and the resulting proteins are not always as useful as scientists would like. Scientists mimic the evolutionary process in the lab by expressing many mutants of a gene with a low level of the desired activity, selecting those with more desirable properties, extracting the DNA, and repeating the cycle in another "round". However, Esvelt explains, a single round of directed evolution typically requires days or longer with frequent human intervention. Evolutionary success strongly depends on the total number of rounds, so he wanted to develop a means of performing laboratory evolution continuously and rapidly. Esvelt engineered a method, called PACE (phage-assisted continuous evolution), which performs dozens of cycles of evolution in a single day without human intervention. He demonstrated that genes with desired new properties emerged in less than a week of evolution. Esvelt hopes that by greatly accelerating laboratory evolution, the PACE method may provide solutions to otherwise intractable directed evolution problems and address novel questions about molecular evolution. Ars Technica summarized his research here.