Marianne Bronner Receives 2013 Conklin Medal

By Marsha E. Lucas

Marianne Bronner was awarded the 2013 Edwin G. Conklin Medal for her distinguished and sustained research in developmental biology and mentoring of the next generation of scientists. Bronner has contributed tremendously to our understanding of the biology of the neural crest, from the timing of its induction at the neural plate border, to the signals that guide its migration pathways. She pioneered the use of single cell injection to track the fates of individual neural crest cells, establishing the multipotency of individual crest cells. Her research expanded into lamprey and amphioxus to uncover the evolutionary origins of both the neural crest and ectodermal placodes. Bronner's group has also been integral in defining the gene regulatory network that underlies neural crest development.

In a recent interview, she expressed how “thrilled” she was to receive the Conklin Medal. “It means a lot to me that it largely came from people who trained with me as well as my colleagues. ... I'm very honored by it—and a bit humbled by it as well.”

Bronner earned her doctorate in biophysics from Johns Hopkins University in 1979. The following year she started her first lab at the University of California, Irvine. She spent 16 years there, rising to become Associate Director of the Developmental Biology Center before moving her lab to the California Institute of Technology in 1996. She is currently the Albert Billings Ruddock Chair of Biology at Caltech.

Bronner has authored over 280 publications and received numerous awards for her research, teaching, and mentoring. In 2009 she was elected to the American Academy of Arts and Sciences and in 2012 The American Society for Cell Biology awarded her the Women in Cell Biology Senior Award for her outstanding scientific achievements and mentoring. She has served the developmental biology community as co-director of the Embryology Course at the Marine Biological Laboratory (1997-2001), SDB President (2009), and is the current president of the International Society for Differentiation.

Beyond the science, Bronner is well-respected for her mentoring of students and postdocs. In their nomination letters, Bronner's former trainees repeatedly describe her as enthusiastic and supportive.

She explained, “I try to get the best I can from everybody by positive reinforcement.” She believes people learn best “by being given a good positive example and constructive criticism.”

“I take the greatest pleasure out of seeing the people who study with me go on and do well,” she said. “It is the most fun thing about this job.”

Remarkably, Bronner lacked good mentorship early on in her career, as her graduate advisor left science for a career in medicine. “There was nobody there particularly taking good care of me, but there was also nobody keeping me down,” she said. “So I guess it forced me early on to be very independent and I think that helped me to develop my own way of doing things.”

Bronner found her role models elsewhere. “There were not very many women, even in developmental biology, at the time when I was a graduate student, and I remember being incredibly struck by the work of Nicole Le Douarin.”

Le Douarin, well-known for her work on the neural crest, pioneered the quail-chick chimera system to study cell fates in the developing embryo. Bronner first met Le Douarin (the 2005 Conklin Medal recipient) when she gave a seminar at Johns Hopkins. “I actually ended up emulating her and working on the same topic and I think as a very strong woman in science, she has continued throughout my career to be somebody I've always looked up to. And so she's probably the person who most shaped my career.”

Bronner was also supported by the late Malcolm Steinberg, a molecular biologist at Princeton University where her parents worked. “I would visit him when I was in graduate school and he sort of took me under his wing, even though I wasn't his student.” Steinberg provided guidance and encouragement “out of the goodness of his heart,” she said. “He had a major role in helping shape me and I really appreciate that.”

In her 30-year career, Bronner has put her stamp on neural crest development research. It is difficult for her to pinpoint which discovery is most significant. “I always think the thing I'm working on right now is the most interesting and significant,” she said. That research happens to be defining the regulatory interactions that generate a neural crest cell.

“We have the tools to take a systems level approach to studying the same questions we've been looking at for decades now. And we know at a molecular level what's going on in a specific cell type to make it differentiate into one type of derivative versus another at a level that we just didn't know before. And that's really exciting. ...But, if you look back at what's most cited, it's probably something I published in the 1980s [laughter].”

Bronner is considered a model for work-life balance by many of her trainees. She credits much of her management skills to being a mother. “I learned how to use small bits of time very efficiently and I think that's served me really well,” she said.

In fact, she encourages this on-the-job training. “I've convinced more than one postdoc that they should have a baby."

Bronner reflected on how meaningful receiving the Conklin Medal was for her, particularly from the developmental biology community. “I've been a member of the Society for Developmental Biology for almost my entire career. I was honored to be elected president in 2009 and I've worked so closely with so many people in this field and I guess I feel like I have reached the height of my career ... that I've finally made it.”