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Decomposition products of cylindrospermopsin : a cyanotoxin produced by Raphidiopsis raciborskii (Woloszynska)

Adamski Michał, Żmudzki Paweł, Bialczyk Jan, Kaminski Ariel, Chrapusta-Srebrny Ewelina, Bober Beata, Duchnik Kornelia

Oceanological and Hydrobiological Studies

2019

Vol. 48, No. 3

227--235

Toxins produced by cyanobacteria (cyanotoxins) and released into water have become a serious problem worldwide due to the increasing morbidity and mortality of living organisms they have caused. The ability to synthesize the cytotoxic alkaloid cylindrospermopsin (CYN) has been demonstrated in several freshwater species of cyanobacteria. CYN is highly chemically stable under environmental factors and decomposes only under alkaline conditions, where it forms derivatives. The toxicity potential of the decomposition products formed at pH 10 combined with high temperature (100°C) or UV-B irradiation (36 μmol m−2 s−1) has been research based on the crustacean Thamnocephalus platyurus (Thamnotoxkit FTM) and bacteria Vibrio fischeri (Deltatox® II) bioassays. This paper is a continuation and completion of our previous experiments and the obtained results showed that the applied conditions contributed to the decomposition of the CYN molecule to non-toxic products and its structural modifications by separating the uracil ring or/and the sulfate group from the tricyclic guanidine moiety, leading to a reduction in its toxicity. To the best of our knowledge, this is the first report describing the toxicity of CYN decomposition products formed under alkaline conditions combined with boiling temperature or UV-B irradiation.

Cadmium concentrations in the Bahía Blanca Estuary (Argentina). Potential effects of dissolved cadmium on the diatom Thalassiosira curviseriata

Andrade S. J., Pucci A. E., Marcovecchio J. E.

Oceanologia

2000

No. 42 (4)

505-520

Concentrations of dissolved and particulate cadmium were measured in the water of the Bahía Blanca Estuary, one of the most highly industrialised regions in Argentina. Simultaneously, Cd contents were also determined in samples of phytoplankton. Thus, the estuary was characterised from the viewpoint of Cd occurrence. Additionally, a microscale environment was selected within the estuary in order to carry out an ecotoxicological study. Thus, environmental parameters (i.e. temperature, salinity, nutrients, chlorophyll a) were measured weekly at Puerto Cuatreros (in the inner estuary) during winter, when the phytoplankton bloom occurs; during the other seasons sampling was done twice a week. In addition, cells of the diatom Thalassiosira curviseriata - the dominant species in the phytoplankton bloom - were isolated and cultivated in the laboratory. The monoclonal cultures obtained were exposed to increasing concentrations of Cd under controlled environmental conditions and the growth rate inhibition was measured. As a preliminary conclusion it was found that Cd levels in the Bahía Blanca Estuary are significantly lower than the EC50 value for T. curviseriata.