title: Optical control and study of biological processes at the single-cell level in a live organism.
abstract: Living organisms are made of cells that are capable of responding to external signals by modifying their internal state and subsequently their external environment. Revealing and understanding the spatio-temporal dynamics of these complex interaction networks is the subject of a field known as systems biology. To investigate these interactions (a necessary step before understanding or modelling them) one needs to develop means to control or interfere spatially and temporally with these processes and to monitor their response on a fast timescale (< minute) and with single-cell resolution. In 2012, an EMBO workshop on 'single-cell physiology' (organized by some of us) was held in Paris to discuss those issues in the light of recent developments that allow for precise spatio-temporal perturbations and observations. This review will be largely based on the investigations reported there. We will first present a non-exhaustive list of examples of cellular interactions and developmental pathways that could benefit from these new approaches. We will review some of the novel tools that have been developed for the observation of cellular activity and then discuss the recent breakthroughs in optical super-resolution microscopy that allow for optical observations beyond the diffraction limit. We will review the various means to photo-control the activity of biomolecules, which allow for local perturbations of physiological processes. We will end up this review with a report on the current status of optogenetics: the use of photo-sensitive DNA-encoded proteins as sensitive reporters and efficient actuators to perturb and monitor physiological processes.
authors.affiliation: Department of Molecular, Cellular and Integrative Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA.
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Feng
authors.forename: Weiting
authors.initials: W
authors.lastname: Zhang
authors.forename: Jianmin
authors.initials: J
authors.lastname: Xu
authors.forename: Carole
authors.initials: C
authors.lastname: Gauron
authors.forename: Bertrand
authors.initials: B
authors.lastname: Ducos
authors.forename: Sophie
authors.initials: S
authors.lastname: Vriz
authors.forename: Michel
authors.initials: M
authors.lastname: Volovitch
authors.forename: Ludovic
authors.initials: L
authors.lastname: Jullien
authors.forename: Shimon
authors.initials: S
authors.lastname: Weiss
authors.forename: David
authors.initials: D
authors.lastname: Bensimon
mesh_terms: D000818:Animals; D005456:Fluorescent Dyes / Q000378:metabolism; D006801:Humans; D008027:Light; D055620:Optical Phenomena; D062308:Optogenetics; D059010:Single-Cell Analysis / Q000379:methods*
chemical_list: D005456:Fluorescent Dyes