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Tuesday, May 24th, 2016
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| 12:00a |
Maiko Kitaoka finds elegance in unexpected places Whether investigating the early-stage development of Drosophila melanogaster or the mystery of “The Hound of the Baskervilles,” Maiko Kitaoka wants to know: how and why?
A biology major in her senior year at MIT, Kitaoka is fascinated by developmental biology. After doing stem cell research in Australia, she spent the last two years working in the lab of Department of Biology Professor Terry Orr-Weaver.
Kitaoka is also a keen reader — lately, she’s found that her 15-minute walks to the lab are a great time to turn a few pages. She loves classics such as “Pride and Prejudice,” “Jane Eyre,” and the Sherlock Holmes novels: “They tell a story, but they also tell you something about human nature, and how people perceive things, or why things happen,” she says.
Born in Japan, Kitaoka moved to the U.S. when she was four. She grew up in Lawrence, Kansas, where her parents finished their graduate degrees; now, they live in Indiana. (Her family’s globe-hopping makes the question “Where are you from?” unusually complicated, she says.)
When she’s not in class or in the lab, Kitaoka might be meeting with MedLinks, a student health and support group that she leads as president. Or she might be spending time with friends, enjoying the last few weeks of senior year. And every so often, she might get struck with an urge to grab her ballet shoes and head downstairs to the studio in her dorm, McCormick Hall, to dance.
Ballet and biology
Kitaoka was 11 years old when she knew she wanted to be a professional ballerina.
She was playing Clara in her ballet school’s annual performance of “The Nutcracker,” featuring all the students in the school. “It was the time of my life,” she says. “When you’re onstage, you can see where the lights come out; the rest is black. There’s this feeling that you are alone with your fellow dancers. I just loved that feeling.”
Kitaoka threw herself into ballet. She spent her summers dancing and eventually began auditioning for year-round pre-professional programs. The summer before her freshman year of high school, a ballet school in New York City offered her a spot in their program. Kitaoka accepted.
In support of their daughter’s dream, Kitaoka’s parents decided that her mother would move with Kitaoka to the city for her high school years. It was an exciting and intense time. “It was a lot of work — and a lot of pain, every so often — but it was a lot of fun,” Kitaoka says.
During her second year in New York, Kitaoka was practicing at the ballet barre when one of her teachers approached. Kitaoka’s back looked a little uneven, she said. “She asked if I had ever been tested for scoliosis,” Kitaoka remembers. “She said, ‘maybe you should look into it.’”
Scoliosis, a sideways curvature of the spine, is a fairly common medical condition, particularly in children and adolescents. Though many cases are mild and require no treatment, some cases can be painful and debilitating. For a dancer, a diagnosis of scoliosis could be career-ending.
The X-rays of Kitaoka’s spine — endless scans, they seemed to her at the time — came back with bad news: She had scoliosis. Her doctor said the condition was fairly advanced, and recommended surgery.
“I was 15 and freaking out,” Kitaoka says. “It was this very stressful time where I didn’t know what was going on, and I didn’t know what to do.”
Deferring the recommended surgery, Kitaoka began a training regimen of swimming, yoga, and Pilates. The dancing that had been the center of her life for so long was suddenly shrouded in uncertainty and discomfort. But there was one part of her life that Kitaoka felt she had control over: She turned her focus to her academic classes.
“In school, I knew what I was doing. This is my assignment, and I have to get it done,” she says.
Kitaoka had always been a good student, but she had been planning for a career in ballet. Now, she began to consider college. She loved English and history, and liked science as well. Her father, an economics professor, encouraged her to apply to MIT. Kitaoka hesitated; would MIT be interested in a student with her background?
A few months later, she had her answer. “I was blown away when I got in,” Kitaoka says. “That was the first time I cried over an acceptance.”
She attended MIT’s Campus Preview Weekend (CPW) that spring, still unsure of her college decision. Those few days on campus — exploring the school with other prefreshmen, sitting in on lectures, and hopping between student-run events — helped make up her mind. “When I came to CPW, I was just blown away by how everybody was so into whatever they were doing,” Kitaoka says. “I love that atmosphere.”
Kitaoka was struck by an introductory biology course she attended, taught by biology professor Hazel Sive. “She was talking about neurobiology, and I remember sitting there thinking, ‘Wow, this is amazing! Biology is so cool!’”
From a single cell
The next year, Kitaoka took the full course that had made such an impression on her at CPW, 7.013 (Introductory Biology). The class piqued her interest in developmental biology in particular. “You start from something so minimal — one cell — and it has everything in it to make everything else,” she says. “That was the underlying thing I really wanted to study.”
Kitaoka spent the summer after her sophomore year in Australia doing stem cell research, solidifying her interest in developmental biology. When she returned to MIT, she joined Terry Orr-Weaver’s lab. Kitaoka’s work focuses on the role of a particular protein in the development of a fruit fly from an egg cell — an oocyte — to an embryo.
“We’re looking at the changes between the two states, seeing what’s happening in between and how the protein levels are changing,” she says.
Kitaoka studies a protein known as a thioredoxin, which helps to regulate the cell’s redox state, facilitating the transfer of electrons between proteins within the cell.
“The cool thing about this protein is that it’s female-specific, and it’s only expressed in the female ovary,” she says. “So the other side of this is, how is this protein different from the ubiquitous thioredoxin that all the flies have in adulthood?”
Redox regulators can play a critical role in the bodies of flies and humans alike, modulating the levels of reactive oxygen molecules in cells. At the right levels, these molecules are important in normal cell functions; otherwise, they can have damaging effects. Understanding how redox states are regulated in cells is key to understanding how cells can deteriorate over time — including during the aging process.
“Fertility does go down, even in flies, the more the female ages,” Kitaoka explains. “There’s this female-specific redox regulator, so what is it doing throughout that period of time?”
As she nears graduation, Kitaoka looks forward to continuing her study of developmental biology next year, when she is beginning graduate school at the University of California at Berkeley. “I really like the basic science concept: You can see the mutant phenotype, you can see that something is wrong. Now how do you figure out what is going on and why?” Kitaoka says.
It was beauty and elegance that captivated Kitaoka in ballet; now, she seeks to unravel the beauty and elegance of a single cell. Though she is far from where she once envisioned herself, Kitaoka has kept an open mind and is taking one step at a time. “For me, the motivating drive is, I will never get this again,” she says. “Take whatever it is life has thrown at you, and take advantage of whatever opportunities you have.” | | 5:00a |
Light can “heal” defects in some solar cells A family of compounds known as perovskites, which can be made into thin films with many promising electronic and optical properties, has been a hot research topic in recent years. But although these materials could potentially be highly useful in applications such as solar cells, some limitations still hamper their efficiency and consistency.
Now, a team of researchers at MIT and elsewhere say they have made significant inroads toward understanding a process for improving perovskites’ performance, by modifying the material using intense light. The new findings are being reported in the journal Nature Communications, in a paper by Samuel Stranks, a researcher at MIT; Vladimir Bulović, the Fariborz Maseeh (1990) Professor of Emerging Technology and associate dean for innovation; and eight colleagues at other institutions in the U.S. and the U.K. The work is part of a major research effort on perovskite materials being led by Stranks, within MIT’s Organic and Nanostructured Electronics Laboratory.
Tiny defects in perovskite’s crystalline structure can hamper the conversion of light into electricity in a solar cell, but “what we’re finding is that there are some defects that can be healed under light,” says Stranks, who is a Marie Curie Fellow jointly at MIT and Cambridge University in the U.K. The tiny defects, called traps, can cause electrons to recombine with atoms before the electrons can reach a place in the crystal where their motion can be harnessed.
Under intense illumination, the researchers found that iodide ions — atoms stripped of an electron so they carry an electric charge — migrated away from the illuminated region, and in the process apparently swept away most of the defects in that region along with them.
“This is the first time this has been shown,” Stranks says, “where just under illumination, where no [electric or magnetic] field has been applied, we see this ion migration that helps to clean the film. It reduces the defect density.” While the effect had been observed before, this work is the first to show that the improvement was caused by the ions moving as a result of the illumination.
This work is focused on particular types of the material, known as organic-inorganic metal halide perovskites, which are considered promising for applications including solar cells, light-emitting diodes (LEDs), lasers, and light detectors. They excel in a property called the photoluminescence quantum efficiency, which is key to maximizing the efficiency of solar cells. But in practice, the performance of different batches of these materials, or even different spots on the same film, has been highly variable and unpredictable. The new work was aimed at figuring out what caused these discrepancies and how to reduce or eliminate them.
Stranks explains that “the ultimate aim is to make defect-free films,” and the resulting improvements in efficiency could also be useful for applications in light emission as well as light capture.
Previous work reducing defects in thin-film perovskite materials has focused on electrical or chemical treatments, but “we find we can do the same with light,” Stranks says. One advantage of that is that the same technique used to improve the material’s properties can at the same time be used as a sensitive probe to observe and better understand the behavior of these promising materials.
Another advantage of this light-based processing is it doesn’t require anything to come in physical contact with the film being treated — for example, there is no need to attach electrical contacts or to bathe the material in a chemical solution. Instead, the treatment can simply be applied by turning on the source of illumination. The process, which they call photo-induced cleaning, could be “a way forward” for the development of useful perovskite-based devices, Stranks says.
The effects of the illumination tend to diminish over time, Stranks says, so “the challenge now is to maintain the effect” long enough to make it practical. Some forms of perovskites are already “looking to be commercialized by next year,” he says, and this research “raises questions that need to be addressed, but it also shows there are ways to address” the phenomena that have been limiting this material’s performance.
“I think the paper provides valuable insight that is likely to help people make more efficient solar cells by figuring out how to reduce the number of iodine vacancies,” says Michael McGehee, a professor of materials science and engineering at Stanford University, who was not involved in this research. “I think it is fascinating that illuminating the perovskites improves their photoluminescence efficiency by enabling iodine to move around and eliminate iodine vacancies. ... This research does not make solar cells better, but it does greatly increase our understanding of how these complex materials function in solar cells.”
In addition to Stranks and Bulović, the team included Anna Osherov of MIT, Dane deQuilettes, Daniel Graham, and David Ginger of the University of Washington, and Wei Zhang, Victor Burlakov, Tomas Leitjens, and Henry Snaith of Oxford University in the U.K. The work was supported by the European Union Seventh Framework Programme, the U.S. National Science Foundation, the Center for Excitonics, an Energy Frontier Research Center at MIT funded by the U.S. Department of Energy, and the National Institutes of Health. | | 3:00p |
Maria Zuber elected as chair of the National Science Board The following is adapted from a National Science Foundation press release.
For the first time in the history of the National Science Foundation (NSF), women now hold three key leadership positions — director of the NSF, and chair and vice-chair of its governing body, the National Science Board (NSB). During its May meeting, the NSB elected Maria Zuber, vice president for research at MIT, as its board chair, and Diane Souvaine, vice provost for research at Tufts University, as its vice chair. Zuber and Souvaine replace Dan Arvizu and Kelvin Droegemeier, who stepped down from the Board after twelve years of service, the last four as chair and vice chair.
Zuber’s research bridges planetary geophysics and the technology of space-based laser and radio systems, and she has published over 200 papers. She has held leadership roles associated with scientific experiments or instrumentation on nine NASA missions and remains involved with six of these missions. The E.A. Griswold Professor of Geophysics at MIT, Zuber is a member of the National Academy of Sciences and the American Philosophical Society, and is a fellow of the American Academy of Arts and Sciences, the American Association for the Advancement of Science, the Geological Society of America, and the American Geophysical Union. In 2002, Discover magazine named her one of the 50 most important women in science. Zuber served on the Presidential Commission on the Implementation of United States Space Exploration Policy in 2004.
Jointly, the 24-member NSB and the NSF director pursue the goals and function of the Foundation. The NSB establishes the policies of NSF within the framework of applicable national policies set forth by the president and Congress. The board also identifies issues that are critical to NSF's future, approves the agency’s strategic budget directions and the annual budget submission to the Office of Management and Budget, and new major programs and awards. The NSB serves as an independent body of advisors to both the president and Congress on policy matters related to science and engineering and education in science and engineering. In addition to publishing major reports, the NSB publishes policy papers and statements on issues of importance to U.S. science and engineering.
NSF director and NSB member ex officio France Córdova said, “I am delighted to say, on behalf of NSF, that we are thrilled with Dr. Zuber's election as chair of the National Science Board. As a superb scientist and recognized university leader, she has the skills needed to help guide the agency's policies and programs. I look forward to working with her as NSF launches new big ideas in science and engineering.”
Zuber is in her fourth year on the NSB and has served on its Committee on Strategy and Budget.
“It is a privilege to lead the National Science Board and to promote NSF’s bold vision for research and education in science and engineering,” said Zuber. “The outcomes of discovery science inspire the next generation and yield the knowledge that drives innovation and national competitiveness, and contribute to our quality of life. NSB is committed to working with Director Córdova and her talented staff to assure that the very best ideas based on merit review are supported and that exciting, emerging opportunities — many at the intersection of disciplines — are pursued.”
Souvaine is in her second term on the NSB and has served as chair of its Committee on Strategy and Budget, chair of its Committee on Programs and Plans, and a member of its Committee on Audit and Oversight. In addition, she co-chaired the NSB’s Task Force on Mid-Scale Research and served three years on the Executive Committee.
A theoretical computer scientist, Souvaine’s research in computational geometry has commercial applications in materials engineering, microchip design, robotics, and computer graphics. She was elected a fellow of the Association for Computing Machinery for her research and for her service on behalf of the computing community. A founding member, Souvaine served for over two years with the NSF Science and Technology Center on Discrete Mathematics and Theoretical Computer Science, that originally spanned Princeton University, Rutgers University, Bell Labs, and Bell Communications Research. She also works to enhance precollege mathematics and foundations of computing education and to advance opportunities for women and minorities in mathematics, science, and engineering.
“I am truly honored and humbled by this vote of confidence from such esteemed colleagues. I do not take this responsibility lightly,” said Souvaine. “The board is proud of NSF’s accomplishments over its 66 years, from the discovery of gravitational waves at LIGO to our biennial Science and Engineering Indicators report on the state of our nation’s science and engineering enterprise. I look forward to working with Congress, the administration, the science and education communities, and NSF staff to continue the agency’s legacy in advancing the progress of science.”
The president appoints NSB members, selected for their eminence in research, education, or public service and records of distinguished service, and who represent a variety of science and engineering disciplines and geographic areas. Board members serve six-year terms, and the president may reappoint members for a second term. NSF's director is an ex officio 25th member of the board. | | 5:00p |
Neuroscientists illuminate role of autism-linked gene A new study from MIT neuroscientists reveals that a gene mutation associated with autism plays a critical role in the formation and maturation of synapses — the connections that allow neurons to communicate with each other.
Many genetic variants have been linked to autism, but only a handful are potent enough to induce the disorder on their own. Among these variants, mutations in a gene called Shank3 are among the most common, occurring in about 0.5 percent of people with autism.
Scientists know that Shank3 helps cells respond to input from other neurons, but because there are two other Shank proteins, and all three can fill in for each other in certain ways, it has been difficult to determine exactly what the Shank proteins are doing.
“It’s clearly regulating something in the neuron that’s receiving a synaptic signal, but some people find one role and some people find another,” says Troy Littleton, a professor in the departments of Biology and of Brain and Cognitive Sciences at MIT, a member of MIT’s Picower Institute for Learning and Memory, and the senior author of the study. “There’s a lot of debate over what it really does at synapses.”
Key to the study is that fruit flies, which Littleton’s lab uses to study synapses, have only one version of the Shank gene. By knocking out that gene, the researchers eliminated all Shank protein from the flies.
“This is the first animal where we have completely removed all Shank family proteins,” says Kathryn Harris, a Picower Institute research scientist and lead author of the paper, which appears in the May 25 issue of the Journal of Neuroscience.
Synaptic organization
Scientists already knew that the Shank proteins are scaffold proteins, meaning that they help to organize the hundreds of other proteins found in the synapse of a postsynaptic cell — a cell that receives signals from a presynaptic cell. These proteins help to coordinate the cell’s response to the incoming signal.
“Shank is essentially a hub for signaling,” Harris says. “It brings in a lot of other partners and plays an organizational role at the postsynaptic membrane.”
In fruit flies lacking the Shank protein, the researchers found two dramatic effects. First, the postsynaptic cells had many fewer boutons, which are the sites where neurotransmitter release occurs. Second, many of the boutons that did form were not properly developed; that is, they were not surrounded by all of the postsynaptic proteins normally found there, which are required to respond to synaptic signals.
The researchers are now studying how this reduction in functional synapses affects the brain. Littleton suspects that the development of neural circuits could be impaired, which, if the same holds true in humans, may help explain some of the symptoms seen in autistic people.
“During critical windows of social and language learning, we reshape our connections to drive connectivity patterns that respond to rewards and language and social interactions,” he says. “If Shank is doing similar things in the mammalian brain, one could imagine potentially having those circuits form relatively normally early on, but if they fail to properly mature and form the proper number of connections, that could lead to a variety of behavioral defects.”
Pinpointing an exact link to autism symptoms would be difficult to do in fruit fly studies, however.
“Although the core molecular machines that allow neurons to communicate are highly conserved between fruit flies and humans, the anatomy of the various circuits that are formed during evolution are quite different,” Littleton says. “It’s hard to jump from a synaptic defect in the fly to an autism-like phenotype because the circuits are so different.”
An unexpected link
The researchers also showed, for the first time, that loss of Shank affects a well-known set of proteins that comprise the Wnt (also known as Wingless) signaling pathway. When a Wnt protein binds to a receptor on the cell, it initiates a series of interactions that influence which genes are turned on. This, in turn, contributes to many cell processes including embryonic development, tissue regeneration, and tumor formation.
When Shank is missing from fruit flies, Wnt signaling is disrupted because the receptor that normally binds to Wnt fails to be internalized by the cell. Normally, a small segment of the activated receptor moves to the cell nucleus and influences the transcription of genes that promote maturation of synapses. Without Shank, Wnt signaling is impaired and the synapses do not fully mature.
“The Shank protein and the Wnt protein family are thought to be involved in autism independently, but the fact that this study discovered that Wnt and Shank are interacting brings the story into better focus,” says Bryan Stewart, a professor of cell and systems biology at the University of Toronto, who was not involved in the research. “Now we can look and see if those interactions between Wnt and Shank are potentially responsible for their role in autism.”
The finding raises the possibility of treating autism with drugs that promote Wnt signaling, if the same connection is found in humans.
“Because the link to Wnt signaling is new and hasn’t been picked up in mammalian studies, we really hope that that can inspire people to look for a connection to Wnt signaling in mammalian models, and maybe that can offer another avenue for how loss of Shank could be counteracted,” Harris says.
The research was funded by the National Institutes of Health and the Simons Center for the Social Brain at MIT. |
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