Fluctuation of algal alkaline phosphatase activity and the possible mechanisms of hydrolysis of dissolved organic phosphorus in Lake Barato |
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Authors: | Shuji Hino |
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Affiliation: | (1) Wisconsin Department of Natural Resources, Bureau of Research, Madison, WI;(2) Center for Limnology, University of Wisconsin, 53706 Madison, WI;(3) Department of Botany and Plant Pathology University of New Hampshire Durham, 03824, NH;(4) Trout Lake Laboratory, Center for Limnology, University of Wisconsin, 54512 Boulder Jct., WI, USA |
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Abstract: | For freshwater cyanobacteria, the autofluorescence of phycocyanin is quite high while the in vivo fluorescence (IVF) yield of chlorophyll-a is relatively low, apparently because of low chlorophyll concentrations associated with photosystem II. In eucaryotic phytoplankton, even those with phycobili-protein accessory pigments (e.g. some cryptophytes), the opposite is true. Thus, an IVF ratio which relates phycocyanin to chlorophyll-a signals could be a good index of relative cyanobacterial abundance in the field. Spectrofluorometric scans of whole cells from laboratory cultures indicated that the ratio Em660 @ Ex630/Em680 @ Ex430 could be a very sensitive cyanobacterial indicator. Tandem flowthrough fluorometers were then fitted with the appropriate interference filters and their discriminatory power was evaluated with mixtures of cyanobacterial and eucaryotic phytoplankton. Although subject to many of the constraints of other IVF assays, tandem fluorometry should be particularly appropriate for real-time mapping of the relative spatial and temporal distributions of broad phytoplankton taxa in continuous vertical of horizontal profiles in lakes. |
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Keywords: | in vivo fluorescence cyanobacteria Cyanophyta spectrofluorometry phycocyanin bluegreen algae |
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