The toxicological response of Anabaena doliolum and Synechococcus leopoliensis to aluminum at selectedpH levels.
Item
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Title
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The toxicological response of Anabaena doliolum and Synechococcus leopoliensis to aluminum at selectedpH levels.
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Identifier
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AAI9707111
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identifier
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9707111
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Creator
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Jones, Edythe Boyer.
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Contributor
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Adviser: Thomas E. Jensen
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Date
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1996
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Botany | Biology, Cell | Biology, Ecology
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Abstract
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The influence of aluminum and pH on growth and survival was studied using two freshwater cyanobacteria, Anabaena doliolum and Synecbococcus leopoliensis. The effective concentration of aluminum, or EC{dollar}\sb{lcub}50{rcub},{dollar} which reduced growth in a population of A. doliolum by 50% upon exposure for 96 hours at pH 7.2 was 0.197 mM. The limiting concentration for S. leopoliensis was 0.145 mM. Cells were again exposed to the metal, 0.32 mM and 0.15 mM, respectively, for 96 hours in medium buffered to pH 5.5, 7.2, and 9.0. Morphometric analyses were carried out using transmission electron microscope (TEM) micrographs of randomly selected cells from each treatment and controls. Analysis of variance (ANOVA) revealed that the combination of aluminum and pH produced significant ultrastructural changes among A. doliolum cells in cell volume, cell wall volume, volumes of polyhedral and polyphosphate bodies and intrathylakoidal space as well as the numbers of polyhedial bodies, polyphosphate bodies, lipid inclusions and cyanophycin granules. Among these cellular sectors and inclusions, more significant variations were recorded between treated and untreated cells at pH 5.5 than at pH 9.0. An increase in relative cell volume among treated cells was the single significant variation at pH 7.2.;The same statistical analysis of S. leopoliensis indicated significant changes in cell wall volume, polyphosphate body volume, intrathylakoidal space volume, thylakoidal surface area, and the number of polyhedral bodies among treated cells. As was true of A. doliolum, more changes in ultrastructure of S. leopoliensis occurred at pH 5.5, but differed in that one more change occurred at pH 7.2 than did at pH 9.0.;Aluminum was not consistently indicated within any cellular sector or inclusion; however, elemental analysis showed intensification of the peak for phosphorus within polyphosphate bodies of cells exposed to all concentrations of aluminum (0.037 mM, 0.185 mM, and 0.370 mM). This pattern is indicative of the detoxification response of cells exposed to heavy metals.;Neither A. doliolum nor S. leopoliensis produced detectable phytochelatins upon exposure to aluminum.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
