Curiouser and Curiouser

By Danielle LaVaque-Manty

Though she grew up catching bugs and always knew she wanted to be a biologist, there was a time when Yukiko Yamashita considered leaving science. During her Ph.D training, she found herself unable to enjoy long hours’ work in a tense environment, leaving “little room for curiosity”.

Fortunately, her postdoctoral experience in Margaret Fuller's lab at Stanford was very different. "She let me have time to think." Fuller talked through Yamashita's ideas with her—"sharing the fun"—but allowed her to learn on her own, and soon her motivation and love of science returned.

This is the approach Yamashita plans to take with students in her own lab. "I don't think you can really teach another person science," she says. "But you can provide guidance and help them figure out what it is that they want to do." At the moment, she employs a technician and two undergraduates, and she looks forward to having graduate students and postdocs to discuss questions with as well. "My biggest motivation is to understand how cells control their fates, and to share the experience with others."

In Japan, Yamashita says, there are fewer women scientists than in the U.S.—although their numbers are growing—and it is not unusual for women, even in her generation, to leave their jobs when they get married, or to retain their positions but become less visible over time as they try to accommodate their careers to the demands of their personal lives and household work. Yamashita credits her mother, a pharmacologist, with giving her the idea that women could keep their jobs for life and not become financially dependent on their husbands. She thinks she gets her curiosity about how things work from her father, "an amateur physicist" and admirer of Albert Einstein who worked in Japan's patent office for many years and who has held patents on several inventions of his own, including a capless, retractable highlighting pen.

Trained as a cell biologist, Yamashita has a unique approach to studying stem cells in multi-cellular organisms, observing the behavior of individual cells as they divide rather than studying them en masse. Margaret Fuller had been studying stem cells for years by the time Yamashita arrived at Stanford, but nobody in her lab had used a cell biological approach. "I see stem cells as being cells first, before they are stem cells," Yamashita says, pointing out that they share ninety-nine percent of their characteristics with other cells. She wants to figure out what accounts for the one percent difference.

Using drosophila, in which stem cells are easy to isolate, she discovered that although stem cells have the same components as other cells, they behave differently, dividing asymmetrically to produce differentiated cells. A stem cell can either differentiate—producing a skin cell, for example—or it can self-renew. "It's an either/or choice for each cell."

Producing too many stem cells can lead to tumorigenesis, while producing too few can lead an organism to run out of other necessities, like new skin cells. Yamashita notes that understanding how cellular mechanisms work may eventually aid other researchers in finding ways to intervene in processes that lead to cancer.

Yamashita's husband, Kentaro Nabeshima, is a cell biologist as well. The two had postdocs at Stanford together, though in different labs, and were hired by the University of Michigan at the same time, Nabeshima in the Department of Cell and Developmental Biology (CDB), and Yamashita in both CDB and the Life Sciences Institute and the Center for Stem Cell Biology. They enjoy living in Ann Arbor, which offers a good environment in which to raise their two-and-a-half year-old daughter.

The LSI, Yamashita says, has been incredibly supportive in helping her make the transition from Stanford to Michigan, even helping her hire a technician to set up her lab before she arrived in January, 2007, so she was able to start work on her experiments right away. "I've never heard of anyone anywhere having their lab up and running within two weeks," she says, noting that making a transition from one university to another can often cause months of delay in one's research. "That was amazing."