High-speed video methods in biophysics

I will give an overview of some recent work in my lab, where we have used high-speed cameras and computational image processing to gain new insight into biological systems. The first area is collective motion in a population of swimming bacteria (specifically E. coli). We adopt ideas from light scattering to measure chemotactic drift in thousands of bacteria at the same time. We compare our results to a parameter-free analytical model of chemotaxis and find excellent agreement [1]. Secondly, we have developed a form of high-speed holographic microscopy to image swimming cells in three dimensions. I will give a brief overview of several systems that we have studied: microgametes of the genus Plasmodium (which causes malaria), chemotaxis in sea urchin sperm cells, and populations of bacteria/archaea. The Plasmodium microgametes are essentially isolated, swimming flagella; by looking at the waves that pass along microgametes as they swim, we uncovered something surprising in the relationship between the swimming stroke and the underlying molecular structure [2]. In conjunction with groups in Bonn and Dresden, we studied the chemosensory system in sea urchin sperm cells. We used a relatively simple model to relate the cells’ internal signalling state to their steering response, as they swim in spatially-controlled 3D chemical gradients [3]. Lastly, we have been tracking populations of bacteria and archaea in three dimensions. This work is at an early stage, but I will talk about where we intend to go with it, and give some preliminary results.

[1] Colin et al., J. Roy. Soc. Interface 11(98) p. 20140486 (2014)

[2] Wilson et al., Proc. Natl. Acad. Sci. USA 110(47) p.18769-18774 (2013)

[3] Jikeli et al., Nat. Comms. 6 p.7985 (2015)