Sander Tans



Sander Tans performed his PhD research in nanotechnology and solid-state physics at Delft University of Technology, with a focus on carbon nanotube devices. In 1998 he obtained his PhD degree, for which he received the Else Kooi prize. He then became a post-doctoral fellow at the University of California at Berkeley, where he worked with Carlos Bustamante in the field of single-molecule biophysics. In 2002 he started a research group at the AMOLF institute in Amsterdam, and since 2009 he is affiliated with the department of Bionanoscience at Delft University of Technology and the Kavli institute of Nanoscience. His current research focuses on the activity of molecular chaperones, the evolution of regulatory networks, and the stability of biological growth at the cellular level. 



Stochasticity and homeostasis in cellular metabolism

Elucidating the role of molecular stochasticity in cellular growth is important to understanding phenotypic heterogeneity and the stability of cellular proliferation. We used time-lapse microscopy to measure fluctuations in the instantaneous growth rate of single cells of Escherichia coli and in the expression of metabolic enzymes. We show that expression fluctuations of catabolically active enzymes can propagate and cause growth fluctuations. Conversely, growth fluctuations propagate back to perturb expression. Homeostasis is promoted by a noise-cancelling mechanism that exploits fluctuations in the dilution of proteins by cell-volume expansion. Thus, molecular noise is propagated not only by regulatory proteins but also by metabolic reactions. The results suggest that cellular metabolism is inherently stochastic, and a generic source of phenotypic heterogeneity.