 James J. Collins

James J. Collins works on synthetic biology and engineering biological systems. MIT Biological Engineering's official profile describes modeling, designing and building synthetic gene circuits and programmable cells.^[ref]

With Timothy S. Gardner and Charles R. Cantor, Collins coauthored the 2000 construction of a genetic toggle switch in Escherichia coli. The paper reports two stable states switched by transient chemical or thermal induction and presents a theory of conditions for bistability.^[ref]

The scientific question is whether feedback can preserve a state after a temporary input disappears. An original contrast is a one-variable relaxation model $\dot{x}=-k(x-x_{\ast })$, with $k>0$. Differences between initial states decay as $e^{-kt}$, so a long transient does not by itself establish two stable memories. A bistable network instead permits different long-term states under the same final external conditions.

An informative experiment therefore compares trajectories from different initial states after removing the switching input, rather than relying only on an endpoint observed while an inducer remains present. The distinction connects the reported toggle to measurable dynamical behaviour. It also illustrates why an engineering design and its biological realization need an explicit model, controls and observed persistence.