Effects of ectoine on behavioral, physiological and biochemical parameters of Daphnia magna exposed to dimethyl sulfoxide.

DMSO is a very common solvent for hydrophobic chemicals that may pose a threat to aquatic organisms. Ectoine (ECT) is a protective amino acid produced by various strains of halophilic bacteria with high potential to alleviate detrimental effects induced by environmental stressors. This amino acid is used in many cosmetics and pharmaceuticals may enter aquatic ecosystems interacting with ions and macromolecules. Little is known on the effects of DMSO and its interaction with ECT on behavioral, physiological and biochemical endpoints of aquatic invertebrates. Therefore, the purpose of the present study was to determine protective effects of DMSO alone and in the combination with ECT on hopping frequency, swimming speed, heart rate, thoracic limb activity, catalase activity and NOx level in an animal model, Daphnia magna subjected to 0.1% and 1% DMSO alone and during combinatorial exposure to ECT (0-25 mg/L) and DMSO for 24 h and 48 h. The results showed that swimming speed, heart rate and thoracic limb activity were inhibited by both 0.1% and 1% DMSO alone however alleviating effects were observed in the combination DMSO + ECT. Thoracic limb activity was higher in the animals exposed to both solutions of DMSO alone, however the parameter was more stimulated at DMSO + ECT. The results suggest that DMSO alone may alter Daphnia behavior and physiological parameters, therefore use of the control group of non-treated animals with DMSO alone would be recommended to avoid data misinterpretation.