A new setup for in vivo fluorescence imaging of photosynthetic activity

Here, we describe a new imaging setup able to assess in vivo photosynthetic activity. The system specifically measures time-resolved chlorophyll fluorescence in response to light. It is composed of a fast digital camera equipped with a wide-angle lens for the analysis of samples up to 10 × 10 cm, i.e. entire plants or petri dishes. In the choice of CCD, we have opted for a 12-bits high frame rate [150 fps (frames per second)] at the expense of definition (640 × 480 pixels). Although the choice of digital camera is always a compromise between these two related features, we have designed a flexible system allowing the fast sampling of images (down to 100 μs) with a maximum spatial resolution. This image readout system, synchronized with actinic light and saturating pulses, allows a precise determination of F0 and FM, which is required to monitor PSII activity. This new imaging system, together with image processing techniques, is useful to investigate the heterogeneity of photosynthetic activity within leaves or to screen large numbers of unicellular algal mutant colonies to identify those with subtle changes in photosynthetic electron flow.

[1]  Pierre Joliot,et al.  Une nouvelle méthode spectrophotométrique destinée à l'étude des réactions photosynthétiques , 1980 .

[2]  F. Wollman,et al.  Biogenesis of cytochrome b 6 in photosynthetic membranes , 2009 .

[3]  R. Sayre,et al.  Modification of the pheophytin midpoint potential in photosystem II: Modulation of the quantum yield of charge separation and of charge recombination pathways , 2004 .

[4]  F. Wollman,et al.  JCB_200812025 1195..1208 , 2009 .

[5]  U. Schreiber,et al.  Methodology and evaluation of a highly sensitive algae toxicity test based on multiwell chlorophyll fluorescence imaging. , 2007, Biosensors & bioelectronics.

[6]  F. Wollman,et al.  The assembly of cytochrome b6/f complexes: an approach using genetic transformation of the green alga Chlamydomonas reinhardtii. , 1994, The EMBO journal.

[7]  P. Bennoun,et al.  New Digital Imaging Instrument For Measuring Fluorescence and Delayed Luminescence , 1998 .

[8]  N. Baker.  Chlorophyll fluorescence: a probe of photosynthesis in vivo. , 2008, Annual review of plant biology.

[9]  R. Park.  Advances in photosynthesis , 1962 .

[10]  Ladislav Nedbal,et al.  Kinetic imaging of chlorophyll fluorescence using modulated light , 2004, Photosynthesis Research.

[11]  P. Bennoun,et al.  Screening algal mutant colonies with altered thylakoid electrochemical gradient through fluorescence and delayed luminescence digital imaging , 1997, Photosynthesis Research.

[12]  F. Zito,et al.  Biochemical and spectroscopic characterization of the covalent binding of heme to cytochrome b6. , 2004, Biochemistry.