Cell-Size Control and Its Evolution at the Single-Cell Level

Virtually all organisms in nature show a relatively narrow range of size distribution. This is a strong indication that life has evolved to regulate cell division, so that cells maintain size homeostasis under all growth conditions. The proposed research will develop and bring together tools and ways of thinking from multiple disciplines to build a quantitative framework for cell size control and homeostasis in the context of cellular decision making.

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Affiliated Investigators

Suckjoon Jun, Ph.D.

University of California, San Diego

Dr. Suckjoon Jun is a theoretical physicist by training, leading an experimental quantitative biology laboratory since 2007. The first phase of his lab was at Harvard University, where he was a Bauer Fellow from 2007 to 2012 under the leadership of Andrew Murray and Erin O’Shea. He moved his lab to UCSD in 2012 to join the campus-wide initiative in quantitative biology, whose vision he shared. While Dr. Jun’s career path from theoretical physics to experimental biology may seem unusual, running through every choice he has made thus far is his desire to understand how one cell becomes two cells.

In research, Dr. Jun aims at principles of basic cellular reproduction, as did the pioneers in the first golden era of microbial physiology from the 1940s to 1960s. He uses mainly a model organism Escherichia coli to answer fundamental, often long-standing biological questions. His earlier work includes biophysical principles of chromosome organization and segregation in bacteria, and his papers are among the most cited in bacterial chromosome cell biology. His team also developed the widely adopted microfluidic “mother machine” during his crossover from chromosome cell biology to growth physiology. Most recently, he reported the adder principle of cell size homeostasis in bacteria, which overturns the 50-year old sizer and timer paradigms.

Dr. Jun’s current research efforts are geared towards building quantitative, overarching principles of how syntheses of the “trinity” that constitute a bacterial cell — the proteins, the chromosome, and the cell walls — are coordinated, and what happens when they ultimately break.