engleski

Ecotoxicological characterization of cyanobacteria and invasive algae from the genus Caulerpa using the concept of effects-directed analyses (EDA)

Effects-directed analyses (EDA) is a powerful multidisciplinary diagnostic tool developed in the field of environmental science that combines the use of advanced chemical and biological methods in order to identify, characterize and prioritize toxicants present in complex environmental samples. So far the EDA approach has been applied for identification and evaluation of environmental contaminants present in non-biological (sediment, surface water, wastewater, soil) complex environmental samples. In this study the EDA approach has been for the first time applied for a detailed ecotoxicological characterization of two types of complex biological samples including eukaryotic and prokaryotic organisms. Invasive tropical green algae from the genus Caulerpa, as well as various cyanobacterial species, produce toxic secondary metabolites that represent a significant threat to the environment and human health, especially during periods of intensive blooms. In order to improve the present portfolio of EDA methodology we applied a modified EDA procedure based on a series of in vitro or small-scale bioassays in combination with advanced chemical analytical protocols. Main goal of this research was to perform a preliminary identification of biologically active substances that cause observed toxic effects and reveal dominant mechanisms of toxicity in these complex biological samples. Non-selective and non-target preparation techniques were used for extraction of a broad range of known and unknown chemical compounds present in both Caulerpa and cyanobacteria. Toxicological endpoints that were monitored in this study included acute and chronic toxicity, as well as interaction with basic phases of cellular detoxification. C. racemosa and C. taxifolia are invasive green algae present in the Adriatic Sea that were used in our EDA study for detailed ecotoxicological characterization. Three terrestrial (Anabaena Č2, Anabaena Č5, Nostoc S8) and three aquatic (Nostoc Z1, Phormidium Z2, Oscillatoria K3) cyanobacterial strains are a part of NSCCC and were used in our modified EDA study as well. The observed toxic effects were the most prominent for both Caulerpa species that exhibited powerful cytotoxicity, both acutely and chronically, and interaction with phase 0 and I of cellular detoxification. Caulerpa species, especially C. taxifolia possess diverse and complex composition of secondary metabolites. Chemical compounds of Caulerpa species responsible for the observed effects are characterized as both polar and lipophilic. CLP was identified as a major metabolite in C. racemosa while CYN was identified as the dominant compound in C. taxifolia. Furthermore, toxic inhibitory effect of CYN compound to anionic uptake transporter (DrOatp1d1) was determined. Cyanobacterial strains also demonstrated strong cytotoxic effects and interaction with phase 0 and I of the detoxification pathway. Of all tested cyanobacteria, aquatic strains obtained the most relevant biological responses to both detoxification phases and are considered to be of grater ecotoxicological importance. Oscillatoria K3 showed to be the most the interesting aquatic cyanobacterial strain because it was the most responsive strain to several observed biological effects. Causable toxicants present in cyanobacterial strains are also characterized as polar and lipophilic. In conclusion, the modified EDA protocol developed and used in this study proved to be useful diagnostic tool for ecotoxicological characterization of complex biological samples.

effects-directed analyses ; Caulerpa ; cyanobacterial strain ; ecotoxicological characterization ; biotests ; cellular detoxification mechanism

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