Periodic production of green fluorescent-fusion division proteins.
Size convergence by the Adder principle.
Fluorescent E. coli growing in the mother machine. Wang et al, Current Biology, 2010.
JT Sauls talks about what he does for qBio and the Jun Lab. See more at the qBio homepage.
James Pelletier is a Hertz Fellow :)
Lysis of exponential phase E. coli cells.
Chromosome compression in the micropiston.
How to make the mother machine.
How to make an oxygen plasma cleaner under $500 (we paid about $10K).
How to duplicate the mother machine using epoxy.

Jun Lab - Quantitative And Physical Approach to Biology

Physics and Molecular Biology - Urey Hall 6249-6253, UCSD

The driving force of our lab is the curiosity and desire to understand how and why the biological systems are the way they are. We are often attracted to long-standing questions in biology, for which quantitative, inter- and multi-disciplinary approaches are essential. We value both logic and intuition, but more of "night science" than "day science."

Just Published and Upcoming

"Comment on ‘Initiation of chromosome replication controls both division and replication cycles in E. coli through a double-adder mechanism’" Fangwei Si, Guillaume Le Treut, Dongyang Li and Suckjoon Jun (in preparation, 2020)
"Mother machine image analysis with MM3" John T. Sauls, Jeremy W. Schroeder, Steven D. Brown, Guillaume Le Treut, Fangwei Si, Dongyang Li, Jue D. Wang and Suckjoon Jun, bioRxiv, (2019) [online]
"Control of Bacillus subtilis Replication Initiation during Physiological Transitions and Perturbations" John T. Sauls, Sarah E. Cox, Quynh Do, Victoria Castillo, Zulfar Ghulam-Jelani and Suckjoon Jun, mBio, 10, e02205-19 (2019) [online][PDF]
"Mechanistic origin of cell-size control and homeostasis in bacteria" Fangwei Si, Guillaume Le Treut, John T Sauls, Stephen Vadia, Petra Anne Levin and Suckjoon Jun, Current Biology, 29, 1-11 (2019) [online][PDF][UCSD news]
"Cell boundary confinement sets the size and position of the E. coli chromosome" Fabai Wu, Pinaki Swain, Louis Kuijpers, Xuan Zheng, Kevin Felter, Margot Guurink, Jacopo Solari, Suckjoon Jun, Thomas S. Shimizu, Debasish Chaudhuri, Bela Mulder* and Cees Dekker*, Current Biology, 29, 2131-2144.e4, (2019)
"Synthesis and degradation of FtsZ quantitatively predicts the first cell division in starved bacteria" K. Sekar, R. Ruscon, JT Sauls, T. Fuhrer, E. Noor, J. Nguyen, VI Fernandez, MF Buffing, M. Berney, S. Jun, R. Stocker and U. Sauer, Mol. Sys. Biol., (2018) 14, e8623 [online][PDF][ETHZ news]
"Promoting an "Auteur Theory" for Young Scientists: Preserving Excitement and Creativity" Arshad Desai and Suckjoon Jun, BioEssays, 1800147, (2018) [PDF]
"Fundamental Principles in Bacterial Physiology - History, Recent progress, and the Future with Focus on Cell Size Control: A Review," Suckjoon Jun, Fangwei Si, Rami Pugatch, and Matthew Scott, Reports on Progress in Physics (2018) [online][PDF][arXiv Preprint]
"Protocol for Construction of a Tunable CRISPR Interference (tCRISPRi) Strain for Escherichia coli," Xintian Li, Cindy Sou, and Suckjoon Jun, BIO-PROTOCOL 7(19):e2574. [online]
"A fundamental unit of cell size in bacteria," Suckjoon Jun and Michael Rust, TRENDS in Genetics 33, 433-435, (2017). [online][PDF]
"Invariance of initiation mass and predictability of cell size in Escherichia coli," Fangwei Si*, Dongyang Li*, Sarah E. Cox, John T. Sauls, Omid Azizi, Cindy Sou, Amy B. Schwartz, Michael J. Erickstad, Yonggun Jun, Xintian Li and Suckjoon Jun, Current Biology 27, 1278–1287 (2017). [OPEN ACCESS (PDF)][Download full dataset][Google Scholar][UCSD News][][ScienceDaily][KENNISLINK (in Dutch!)][Commentary in Current Biology]
Unit cell
"tCRISPRi: tunable and reversible, one-step control of gene expression," Xintian Li, Yonggun Jun, Michael J. Erickstad, Steven D. Brown, Adam Parks, Donald L. Court and Suckjoon Jun, Scientific Reports 6, 39076 (2016).[PDF] [strain request]
"Isolation and characterization of bacterial nucleoids in microfluidic devices," James Pelletier and Suckjoon Jun, Methods in Molecular Biology (in press).
"Adder and a coarse-grained approach to cell size homeostasis in bacteria," John T Sauls, Dongyang Li, and Suckjoon Jun, Current Opinion in Cell Biology, 38:38-44 (2016). [online] [PDF]

Select Recent Publications

"Single-cell physiology," Sattar Taheri, Steven Brown, John T. Sauls, Dustin McIntosh, Suckjoon Jun, Annual Review of Biophysics, 44, 123-42 (2015). [download] [Google Scholar]
S. Taheri-Araghi, S. Bradde, J. T. Sauls, N. S. Hill, P. A. Levin, J. Paulsson, M. Vergassola, and S. Jun,
Current Biology (2014) [online] [PDF+extended SI]
[Google Scholar] [news coverage] [download data]
Size convergence
"Cell-size maintenance: universal strategy revealed," S. Jun & S. Taheri-Araghi, Trends in Microbiology (2014) [online] [PDF] [Google Scholar]
"Bending forces plastically deform growing bacterial cell walls," A. Amir, F. Babaeipour, D. McIntosh, D. R. Nelson, S. Jun, Proc. Nat. Acad. Sci. USA (2014).
Bending forces plastically deform growing bacterial cell walls
"The bacterial chromosome: a physical biologist’s apology. A perspective." Appeared in Small Things Considered [click] (2014).
The bacterial chromosome: a physical biologist’s apology. A perspective.
[Link to David Goodsell’s new high-resolution E. coli illustration]
"The multi-fork Escherichia coli chromosome is a self-duplicating and self-segregating thermodynamic ring polymer,"
B. Youngren, H. J. Nielsen, S. Jun, and S. Austin, Genes & Development (2014).
The multi-fork Escherichia coli chromosome is a self-duplicating and self-segregating thermodynamic ring polymer
"Physical manipulation of the Escherichia coli chromosome reveals its soft nature," Pelletier & Halvorsen et al., PNAS Plus (2012).
Physical manipulation of the Escherichia coli chromosome reveals its soft nature
"Entropy as the driver of chromosome segregation," S. Jun and A. Wright, Nat. Rev. Microbiol. (2010)
[online] [PDF] [Small Things Considered]
[Google Scholar]
Entropy as the driver of chromosome segregation
"Robust growth of Escherichia coli," Wang et al., Curr. Biol. (2010)
[online] [PDF] [F1000] [Small Things Considered]
[Google Scholar] [The Scientist Top 7 Biology]
[The Scientist Top 7 Biochemistry] [download data]
Robust growth of Escherichia coli


Congratulations to Orianna, she is one of the 33 recipients of 2019-2020 UC San Diego Physical Sciences Dean’s Undergraduate Award for Excellence, out of nearly 4,000 undergraduate majors in the Departments of Chemistry and Biochemistry, Mathematics, and Physics! (Nov, 2019)
JT has defended and officially become a PhD. Congratulations Dr. Sauls! (Sept, 2019)
BREAKING NEWS: We have made our image analysis package for mother machine experiments publicly available. See MOTHER-MACHINE IMAGE ANALYSIS on the top of our site. More information to follow in the 2nd half of 2019. (Aug, 2019)
Welcome aboard Saransh Umale! Saransh is a PhD student in the biology graduate program at UCSD. (May, 2019)
Welcome Tejal Agarwal as a visiting PhD student from IISER Pune (India)! Tejal will be working on chromosome organization here for six months. (March, 2019)
Dongyang defended his PhD thesis! (December, 2018)
We welcome new graduate student Ryan Thiermann to join the lab! We welcome Liyana Valiya Peedikakkal to come back as a postdoc! (October, 2018)
We welcome Mikkel Svenningsen from Niels Bohr Institute in Denmark for a 3-month visit. (February, 2018)
Our review on bacteria physiology is accepted to Reports on Progress in Physics (ROPP), check it out on our publication page! (January, 2018)
The lab had a road trip to San Francisco! (December, 2017)
Our undergrad lab alumni are moving on to the next stage in their academic lives. Eden Aklile will start at Northwestern and Zulfar Ghulam-Jelani at Duke in their respective top programs. We wish them all the very best! (August, 2017)
We now have a revamped research webpage. (June, 2017)
Suckjoon has been promoted to Associate Professor with tenure. Congratulations! (May, 2017)
We welcome our new postdoc Guillaume Le Treut, from Commissariat à l'énergie atomique et aux énergies alternatives (CEA, Paris, France). (February, 2017)
We welcome Jacopo Solari, a PhD student from AMOLF for a 3-month visiting. (January, 2017)
Congratulations to graduating senior Amy Schwartz. She has been awarded the UCSD Physics Dept's John Holmes Malmberg Prize. Amy will enter graduate school here at UCSD in the fall. (June, 2016)
Dr. Ashley Cadby arrived from the University of Sheffield, UK for a 6-month sabbatical with us. (February 1, 2016)
We welcome Kazuki Yoda, a visiting undergraduate from the University of Tokyo, for a 3-month internship. (January 19, 2016)
Many congratulations to Sattar! He will join California State University Northridge in the Fall as an Assistant Professor in Physics. (July, 2015)
We welcome two new postdocs, Jia-Wei from Cornell and Fangwei from Johns-Hopkins. They will start in September. (July, 2015)
Many congratulations to Yonggun Jun! After considering multiple offers, he has decided to join National Central University in Taiwan as a faculty member in biophysics in 2016. We are happy for his new chapter in life and career. (May, 2015)
Benjamin just arrived from École Normale Supérieure (Paris, France) for 6-month internship. (February 20, 2015)
Suckjoon has been selected as a Scialog Fellow for Scialog: Molecules Come to Life by Research Corporation and Gordon & Betty Moore Foundation. (July 16, 2014)
Suckjoon has been awarded a 5-year NSF CAREER Award (MCB, $1.15M) Cell cycle and cell size control in bacteria. (July 22, 2013)
Suckjoon has been named one of the 22 Pew Scholars. [UCSD News] [Press Release] (June 13, 2013)
Our lab alumnus (at Harvard), James Pelletier (now at MIT), has been named a Hertz Fellow. Congratulations! (April 15, 2013)
Thanks to the Paul G. Allen Foundation, Suckjoon is one of the five Allen Distinguished Investigators. [UCSD News] [Seattle Times] [Xconomy] (February 28, 2013)
Thanks to Brendan at UCSD Physics IT, the beta version of our web site is ready for public. (November 13, 2012)
Our lab has officially moved from Harvard to UCSD. The new lab space at UCSD is currently under construction in Urey Hall 6249-6253, to be completed before next year. (October 4, 2012)
James' paper has just appeared online at PNAS. Highlight or full article.(September 14, 2012)
Jean-Yves Bouet (CNRS) visited us.(June 8-12, 2012)
Another brave theoretical physicist, Ariel Amir (Harvard Junior Fellow), will start his adventure in experimental physical biology.(May 2, 2012)
Stuart Austin (NCI) and Henrik Nielsen will be visiting us to discuss bacterial chromosomes.(April 25-28, 2012)
Please visit The Cost of Knowledge (boycott Elsevier), and sign, if you agree.
It will take some serious courage, especially for junior scientists, since Elsevier owns Cell, Current Biology, and many others.
For background information, read the blogposts by Tom Gowers, Terence Tao, HMS; articles in the Guardian, NYT, the Boston Globe.
If you want to have a good laugh, investment firms seem to know a lot about Open Access Movement -- read this.(April 22, 2012)
Suckjoon will be giving a keynote speech at the Chemical Biophysics Symposium in Toronto, Canada.(April 13-15, 2012)
Sattar has been accepted to Advanced Bacterial Genetics course at Cold Spring Harbor Laboratory.
Intense 3 weeks in June!(April 2, 2012)
Petra Levin (Washington Univ., St Louis) visited us to discuss bacterial cell cycle in E. coli and B. subtilis.(January 6-7, 2012)
The complete data sets for the mother machine paper are available for download.
Please see here or here before writing us with requests. Thanks.(November 28, 2011)
Muyoung Heo has been selected as one of the 15 Fellows in natural sciences awarded by the President of Korea.
It is a great deal and it comes with a very generous package for his future research.(August 30, 2011)

Current Lab Members

  • Sarah Cox (lab manager, research assistant)
  • Suckjoon Jun (PI)
  • Orianna Kou (biophysics, undergrad)
  • Guillaume Le Treut (physics, postdoc)
  • Dongyang Li (biology, postdoc)
  • Liyana Valiya Peedikakkal (biophysics, postdoc)
  • Aaron Ren (biophysics, undergrad)
  • JT Sauls (systems biology, grad student)
  • Fangwei Si (applied physics, postdoc)
  • Dillion Thao (biology, undergrad)
  • Ryan Thiermann (biophysics, grad student)
  • Saransh Umale (biology, grad student)
  • Daniel Villarreal (biophysics, undergrad)

Join Us

We are looking for graduate students, postdocs, and scientists.See the JOIN page for more information.