Concurrent imaging of chlorophyll fluorescence, Chlorophyll a content and green fluorescent proteins‐like proteins of symbiotic cnidarians. (19th July 2014)

• Record Type: Journal Article
• Authors: Leal, Miguel Costa; Jesus, Bruno; Ezequiel, João; Calado, Ricardo; Rocha, Rui Jorge Miranda; Cartaxana, Paulo; Serôdio, João
• Is Part Of: Marine ecology. Volume 36:Number 3(2015:Sep.)
• Page Start: 572
• Page End: 584
• Publication Date: 2014-07-19
• Subjects: Marine ecology -- Periodicals; 577.705
• DOI: 10.1111/maec.12164
• Languages: English
• ISSNs: 0173-9565

Abstract

<abstract abstract-type="main" id="maec12164-abs-0001"> <title>Abstract</title> <p>Research on photosynthetic cnidarians has been mainly focused on the symbiosis established between the cnidarian host and its dinoflagellates endosymbionts from genus <italic>Symbiodinium</italic>. Despite the potential of imaging techniques for assessing the spatial distribution of key parameters of cnidarian photobiology, such as photochemical activity, chlorophyll a content or green fluorescent proteins (GFPs), to our best knowledge, no study has ever attempted to simultaneous map these three features. In this study, we developed a modified imaging pulse amplitude fluorometer by applying excitation light of different wavelengths and selectively detecting short spectral bands through bandpass filters. The imaging system was used to sequentially excite and quantify chlorophyll variable fluorescence (maximum quantum yield of photosystem II, F<sub>v</sub>/F<sub>m</sub>), Chl <italic>a</italic> content (normalized difference vegetation index) and relative content of GFPs. The spatial distribution of these photophysiological parameters was mapped both horizontally, across the surface of the soft corals <italic>Sarcophyton</italic> cf. <italic>glaucum</italic> and <italic>Sinularia flexibilis</italic> and the zoanthid <italic>Protopalythoa</italic> sp., and vertically, throughout a vertical section of <italic>S</italic>. cf. <italic>glaucum</italic>. Results showed bleached areas within each individual coral colony and registered photophysiological changes with <italic>S</italic>. cf. <italic>glaucum</italic> tissue depth. Analysis of <italic>Protopalythoa</italic> sp. polyps' expansion revealed differential surface patterns of NDVI and GFP concentration, and a negative relation between these latter parameters within each polyp. This novel non‐invasive approach allowed a high‐resolution characterization of the spatial relationship between these key parameters through the analysis of image information on a pixel‐by‐pixel basis, which has great potential for investigating the physiological state of symbiotic associations.</p> </abstract>