Ectoine alleviates behavioural, physiological and biochemical changes in Daphnia magna subjected to formaldehyde

Physiological endpoints in daphnid acute toxicity tests

Daphnids are freshwater crustaceans used in toxicity tests. Although lethality and immobilisation are the most commonly used endpoints in those tests, more sensitive parameters are required for determination of sublethal acute effects of toxicants. The use of various physiological endpoints in daphnids is considered as a low-cost and simple alternative that meets the 3R's rule (Replacement, Reduction, Refinement) criteria. However, currently there is no review-based evaluation of their applicability in toxicity testing. This paper presents the results on the most commonly determined physiological parameters of Daphnia in ecotoxicological studies and human drug testing, such as feeding activity, thoracic limb movement, heart rate, cardiac area, respiratory activity, compound eye, mandible movements and post-abdominal claw contractions. Furthermore, their applicability as promising endpoints in the assessment of water quality or drug testing is discussed.

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.

Procaine penicillin alters swimming behaviour and physiological parameters of Daphnia magna

Procaine penicillin (PP) is a β-lactam antibiotic widely used in human and veterinary medicine. Although PP is detected in surface water, little is known on its effects on aquatic invertebrates. Our aim was to determine the influence of PP on swimming behaviour (track density, swimming speed, turning angle, hopping frequency) and physiological activity (oxygen consumption, heart rate, thoracic limb movement) of a freshwater invertebrate Daphnia magna exposed to PP at concentrations of 11.79 mg/L, 117.9 mg/L and 1179 mg/L for 2 h and 24 h. The results showed no mortality; however, reduction of swimming activity manifested by the decreased track density, swimming speed and turning angle noted in Daphnia exposed to all the concentrations of PP. Increase of oxygen consumption was observed after 2-h exposure; however, decrease of this parameter was found after 24 h. PP also reduced heart rate and thoracic limb movement in a concentration-dependent manner. The results suggest that the antibiotic should not induce mortality; however, it may affect swimming behaviour and physiological parameters of Daphnia magna particularly inhabiting aquaculture facilities with intensive antibiotic treatment. On the basis of the present results, we also suggest higher sensitivity of behavioural and physiological parameters of cladocerans than the commonly used endpoints: mortality or immobilisation and their possible application as a part of early warning systems in monitoring of surface water toxicity.

Effects of apomorphine, a dopamine agonist, on Daphnia magna: Imaging of swimming track density as a novel tool in the assessment of swimming activity

Apomorphine (APO) is a non-selective agonist of dopamine receptor activating D2-like receptors. Although Daphnia has been used in neurotoxicology in toxicity testing, little is known on its behavioural and physiological responses to dopamine receptors ligands. Therefore, the aim of our study was to determine swimming behaviour (swimming track density, speed, turning activity) and physiological parameters such as heart rate, thoracic limb activity and post-abdominal claw movement frequency in daphnids exposed for 1, 2 and 4h to concentrations of 0.3, 3 and 30mg/L of APO. The results showed the most significant decrease of behavioural endpoints such as swimming track density, speed and degree of turning angles of daphnids exposed for 4h to the highest concentrations of APO. The study also showed that a decrease of thoracic limb activity was found after 2 and 4h but only at the highest concentration. Heart rate was not affected by APO which may be a result of a lack of signalling with dopamine receptors in the heart of Daphnia. Therefore, activity of this organ seems to be not a valuable physiological biomarker in the assessment of effects induced by dopamine receptor ligands. The study also showed that our new methodological approach, imaging of swimming track density may be a promising tool for studying the effects of neuroactive substances on locomotor system activity of Daphnia magna.

Post-irradiation protective effects of ectoine on brain and testicles in male mice

BACKGROUND

The present study aimed to investigate the possible post-irradiation protective effects of ectoine on CNS and testes of male mice.

METHODS

The study included thirty male Swiss albino mice (20-22 gm). Mice were divided into five groups (six each); controls (injected intraperitoneally with 0.2ml saline), irradiated group 1 (received six Gy whole body x-irradiation single dose, injected with saline, and sacrificed after one day), irradiated group 2 (x-irradiated, injected with saline, and sacrificed after one week), ectoine group 1 (x-irradiated, injected with 200mg/kg ectoine, and sacrificed after one day), and ectoine group 2 (x-irradiated, injected daily with 200mg/kg ectoine, and sacrificed after one week). IL-1β, IL-6, IL-10, PGE₂, MDA, GSH, GSSG, and GSH/GSSG ratio were evaluated in CNS and testes.

RESULTS

IL-1β, IL-6, IL-10, PGE₂, and MDA are significantly elevated in the CNS and testes of x-irradiated groups when compared with controls. IL-1β, IL-6, IL-10, and PGE₂ significantly elevated at one week than one day while MDA significantly decreased. A significant decrease in the concentration of GSH and in the GSH/GSSG ratios coupled with an opposite effect on GSSG was noted. Ectoine treatment significantly ameliorated the biochemical effects induced by whole body x-irradiation. All the tested parameters tended to go back to near control values. It was noted that the modulating action was dependent on the accumulation of ectoine as it was more effective after repeated administration.

CONCLUSION

Ectoine has post-irradiation protective effects on CNS and testes via its action on inflammatory and oxidative stress pathways.

Daphnia swimming behaviour as a biomarker in toxicity assessment: A review

Daphnia is a motile common model organism widely used in ecotoxicological testing. Although mortality and immobilisation are the main endpoints used for determination of toxicity, detection of subtle alterations induced by some chemicals particularly at lower levels may require more sensitive biomarkers. As a number of studies indicated that swimming behaviour may be altered by pesticides, nanoparticles, bacterial products or other chemicals, analysis of its various parameters is considered as a novel methodological approach for toxicity assessment and monitoring of water quality. This paper presents the current state of knowledge on the effects induced by various chemical compounds on the parameters of swimming behaviour of Daphnia and systems developed for its analysis. Advantages and limitations of swimming behaviour as a tool in toxicological studies are also discussed.

Ectoine as a promising protective agent in humans and animals

Ectoine is a compatible water molecule-binding solute (osmoprotectant) produced by several bacterial species in response to osmotic stress and unfavourable environmental conditions. This amino acid derivative can accumulate inside cells at high concentrations without interfering with natural processes and can protect the cell against radiation or osmotic stress. This brief review presents the current state of knowledge about the effects of ectoine on animals and focuses on its practical use for enzyme stabilisation, human skin protection, anti-inflammatory treatment, inhibitory effects in neurodegenerative diseases, and other therapeutic potential in human or veterinary medicine.