A trick of the light: the optical properties of living cytoplasm which can mislead

Abstract

Our understanding of the dynamic chemical changes within living cells has increased enormously as a direct result of imaging and manipulating techniques which rely on the use of light to penetrate the cell. These optical techniques are at the intersection of the three sciences: physics, chemistry and biology. However, the understanding of the physics of illumination (e.g. lasers, confocal microscopy) and the chemistry of fluors (synthetic and protein) is way ahead of the understanding of the biological interface posed by the cell itself. In this critical review we will show that ignoring the optical properties of living cells can lead to serious errors of interpretation and that even seemingly compelling images can result from a “trick of the light”.