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Sites of toxicity of specific photooxidation products of anthracene to higher plants: Inhibition of photosynthetic activity and electron transport in Lemna gibba L. G‐3 (Duckweed)
Author(s) -
Mallakin Ali,
Babu T. Sudhakar,
Dixon D. George,
Greenberg Bruce M.
Publication year - 2002
Publication title -
environmental toxicology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.813
H-Index - 77
eISSN - 1522-7278
pISSN - 1520-4081
DOI - 10.1002/tox.10080
Subject(s) - photosynthesis , lemna gibba , photosystem ii , toxicity , chlorophyll fluorescence , lemna , chemistry , electron transport chain , anthracene , chlorophyll , biology , environmental chemistry , botany , photochemistry , aquatic plant , ecology , macrophyte , organic chemistry
Sites of toxicity of polycyclic aromatic hydrocarbons (PAHs) were examined to determine if inhibition of photosynthetic activity could be correlated to whole‐organism toxicity. The inhibition of photosynthesis was observed by detecting the induction kinetics of endogenous chlorophyll a (Chl a ) fluorescence. Anthracene (ANT) photooxidation products were applied to the aquatic higher plant Lemna gibba L. G‐3 at concentrations ranging from 0.01 to 10 ppm. The impact on Chl a fluorescence was found to correlate with whole‐organism toxicity for the 13 PAH compounds tested in this in vivo study. The mechanism of toxic action starts with inhibition of photosystem I (PSI) or the cytochrome‐b6/f complex, followed by photooxidative damage to photosystem II (PSII). To study the effects of oxygenated ANTs on photosynthesis in vivo, the IC 50 s for F V / F M (PSII activity) and F Q / F M (activity downstream from PSII) were determined. The IC 50 s for a decrease of F Q / F M for all 13 chemicals were on average twofold lower than those for F V / F M . F V / F M was found to be a measure of acute toxicity, whereas F Q / F M was found to be a measure of chronic toxicity. Thus, Chl a fluorescence by use of the whole organism was able to detect the impacts of photomodified ANT products and indicate a site of action for the chemicals. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 462–471, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10080