Arsenic accumulation and thiol status in lichens exposed to As(V) in controlled conditions
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Thalli of epiphytic lichen Hypogymnia physodes (L.) Nyl. and terricolous Cladonia furcata (Huds.) Schrad., collected from an area with background arsenic concentrations, were exposed to 0, 0.1, 1 and 10 μg mL−1 arsenate (As(V)) solutions for 24 h. After exposure they were kept in the metabolically active state for 0, 24 and 48 h in a growth chamber. In the freeze dried samples glutathione (GSH), glutathione disulphide (GSSG), cysteine (Cys) and cystine were analysed and induction of phytochelatin (PC) synthesis measured by reversed-phase high-performance liquid chromatography in combination with fluorescence detection or UV spectrometry. Total arsenic content in thalli was measured by instrumental neutron activation analysis (INAA). In H. physodes, which contained higher amounts of arsenic compared to C. furcata, total glutathione content significantly decreased in samples exposed to 10 μg mL−1 As(V), whereas in C. furcata a significant increase was observed. In both species PC synthesis was induced in thalli exposed to 10 μg mL−1.
KeywordsLichens Arsenic Glutathione Phytochelatins Half-cell reduction potential Hypogymnia physodes Cladonia furcata
Phytochelatin (n = number of γ-Glu-Cys units)
Half-cell reduction potential for GSSG/2GSH couple
This research was financed by the Slovenian Research Agency through programmes P1-0143 and PR-00238. The authors wish to thank Emanuela Vurro from the Department of Evolutionary and Functional Biology, University of Parma, Italy, for technical assistance. Astrid Wonisch and Klaus Remele from the Institute of Plant Sciences, University of Graz, Austria, are gratefully acknowledged for instructions on determination of thiols and their corresponding disulphides and much technical help.
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