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Green fluorescent protein regulation in the coral Acropora yongei during photoacclimation
Melissa S. Roth, Michael I. Latz, Ralf Goericke, Dimitri D. Deheyn


Reef-building corals inhabit high light environments and are dependent on photosynthetic endosymbiotic dinoflagellates for nutrition. While photoacclimation responses of the dinoflagellates to changes in illumination are well understood, host photoacclimation strategies are poorly known. This study investigated fluorescent protein expression in the shallow-water coral Acropora yongei during a 30 day laboratory photoacclimation experiment in the context of its dinoflagellate symbionts. Green fluorescent protein (GFP) concentration measured by Western blotting changed reversibly with light intensity. The first 15 days of the photoacclimation experiment led to a ∼1.6 times increase in GFP concentration for high light corals (900 μmol quanta m–2 s–1) and a ∼4 times decrease in GFP concentration for low light corals (30 μmol quanta m–2 s–1) compared with medium light corals (300 μmol quanta m–2 s–1). Green fluorescence increased ∼1.9 times in high light corals and decreased ∼1.9 times in low light corals compared with medium light corals. GFP concentration and green fluorescence intensity were significantly correlated. Typical photoacclimation responses in the dinoflagellates were observed including changes in density, photosynthetic pigment concentration and photosynthetic efficiency. Although fluorescent proteins are ubiquitous and abundant in scleractinian corals, their functions remain ambiguous. These results suggest that scleractinian corals regulate GFP to modulate the internal light environment and support the hypothesis that GFP has a photoprotective function. The success of photoprotection and photoacclimation strategies, in addition to stress responses, will be critical to the fate of scleractinian corals exposed to climate change and other stressors.


  • This research was supported by a National Science Foundation Graduate Research Fellowship (M.S.R.); the Scripps Institution of Oceanography's John Dove Isaacs Professorship of Natural Philosophy (Nancy Knowlton); the Air Force Office of Scientific Research Biomimetics, Biomaterials, and Biointerfacial Sciences program (grant no. FA9550-07-1-0027; D.D.D. and M.I.L.); and the Department of Scripps Institution of Oceanography (M.S.R.). The authors would like to thank M. Roadman for assistance with HPLC, E. Kisfaludy and F. Nosratpour for aquarium support, the Birch Aquarium at the Scripps Institution of Oceanography for providing corals, V. Vacquier and M. Landry for use of equipment, G. Moy for antibody development support, B. Magit for general assistance, S. Bornheimer and anonymous reviewers for comments on the manuscript.

  • Supplementary material available online at http://jeb.biologists.org/cgi/content/full/213/21/3644/DC1


    fluorescent protein
    variable fluorescence/maximum fluorescence
    full-width at half-maximum
    green fluorescent protein
    high light treatment
    low light treatment
    medium light treatment
    pulse amplitude modulated
    photosystem II
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