03 November 2015 ICFO in Reports of Progress in Physics

Frame by frame reconstruction of SPT trajectories (white dashes)

ICFO publishes review of progress in single particle tracking Single particle tracking is a powerful optical approach to study a variety of dynamic processes in life sciences. A recent review written by Carlo Manzo and ICREA Professor at ICFO Maria Garcia-Parajo published in Reports of Progress in Physics discusses the principles of single particle tracking and highlight novel insights on the role of lateral diffusion regulating the function of individual molecules inside living cells.

Optical microscopy has been for centuries a key tool to study living cells with minimum invasiveness. The advent of single molecule techniques over the past two decades has revolutionized the field of Cell Biology by providing a more quantitative picture of the complex and highly dynamic organization of living systems. Amongst these techniques, single particle tracking (SPT) has emerged as a powerful approach to study a variety of dynamic processes in life sciences. SPT provides access to the dynamics of single molecule behavior in the natural context of living cells thereby allowing a complete statistical characterization of the system under study.

The quantification of molecular diffusivity has fundamental importance in studying the function of biological molecules in living cells. This is because mobility is often affected by interactions between the molecule under study and its surroundings, reporting therefore not only on the occurrence of molecular interactions, but importantly, it allows inferring on its functional role for cell response. In this review, Carlo Manzo and Maria Garcia-Parajo describe the foundations of SPT together with novel optical implementations that allow nowadays the investigation of single molecule dynamic events with increasingly high spatiotemporal resolution using molecular densities closer to physiological expression levels. The review further outlines some of the algorithms for the faithful reconstruction of SPT trajectories as well as data analysis, and highlight biological examples where the technique has provided novel insights on the role of diffusion regulating cellular function. The last part of the review concentrates on different theoretical models that describe anomalous transport behaviour and ergodicity breaking observed from SPT studies in living cells.