New Digital Imaging Instrument For Measuring Fluorescence and Delayed Luminescence

We describe a new digital imaging instrument designed to monitor fluorescence and delayed luminescence of photosynthetic systems (algal or bacterial colonies grown on Petri dishes, leaves). The setup includes light-emitting diodes, a cooled line transfer charge-coupled device (CCD) camera, a personal computer and appropriate software which allows capture of pictures and kinetics in real time during illumination. This instrument provides fluorescence images under actinic or non-actinic illumination and makes the fluorescence induction kinetics of individual colonies readily accessible with good time resolution. It brings great refinement to procedures for screening colonies that are altered in photosynthetic electron transfer owing to appropriately computed fluorescence images. This instrument allows, for the first time, to capture delayed luminescence images, thus opening the way to screening for mutants that have an altered permanent or light-induced electrochemical gradient across thylakoid membranes.