Light microscopy and adaptive optics, my uncensored and biased opinions

Chemotaxis of bacteria is a molecular mechanism by which they sense chemicals and swim through  a biased random walk toward preferred concentrations. It has been studied extensively since late 60-s and became a triumph of quantitative system biology, thanks to giants like Julius Adler , Howard C. Berg , Daniel Koshland , to name a few. Perhaps the most instrumental in this scientific revolution was Howard Berg’s tracking microscope ( Berg 1971; PDF ), which could follow a freely swimming E.coli cell in 3D in real time . Yes, in 1971. It allowed precise quantification of cell swimming trajectories in spatial and temporal gradients of chemicals, which led to discovery that E.coli performs a biased random walk, with longer runs toward increasing concentrations of attractive chemicals ( Berg and Brown, 1972; PDF ). This work laid the foundation of quantitative approach to bacterial chemotaxis, which led to multiple breakthroughs on it’s biochemical and physical mechanisms. Even today