Effects of ectoine on behavioural, physiological and biochemical parameters of Daphnia magna.

Ectoine (ECT) is a compatible solute produced by soil, marine and freshwater bacteria in response to stressful factors. The purpose of our study was to determine the possible toxic influence of ECT on Daphnia magna. We determined the following endpoints: survival rate during exposure and recovery, swimming performance, heart rate, thoracic limb movement determined by image analysis, haemoglobin level by ELISA assay, catalase and nitric oxide species (NOx) by spectrophotometric methods. The results showed 80% survival of daphnids exposed to 50mg/L of ECT after 24h and 10% after 90h, however lower concentrations of ECT were well tolerated. A concentration-dependent reduction of swimming velocity was noted at 24 and 48h of the exposure. ECT (at 2.5 and 4mg/L) induced an increase of heart rate and thoracic limb movement (at 2.5, 4 and 20mg/L) after 24h. After 10h of the exposure to ECT daphnids showed a concentration-dependent increase of haemoglobin level synthesized and accumulated in the epipodite epithelia. After 24h we noted a concentration-dependent decrease of haemoglobin level and its lowest value was found after 48h of the exposure. ECT at a concentration of 20 and 25mg/L slightly stimulated catalase activity after 24h. NOx level was also increased after 10h of the exposure to 20 and 25mg/L of ECT reaching maximal activity after 24h. Our results suggest that ECT possesses some modulatory potential on the behaviour, physiology and biochemical parameters in daphnids.

Effects of microcystin-containing cyanobacterial extract on hematological and biochemical parameters of common carp (Cyprinus carpio L.).

The aim of the study was to assess the effects of a cyanobacterial extract containing microcystins (MCs) on selected hematological and biochemical parameters in common carp (Cyprinus carpio L.), as well as to determine the accumulation of toxins in fish tissues. The fish were immersed for 5 days in water containing toxins at a final concentration of 12 µg/L of microcystin LR equivalent. Microcystin LR residues were detected in fish liver, reaching 207, 238 and 260 ng/g f.w. of the tissues taken 24 h, 72 h and 5 days after the end of intoxication, respectively. The most substantial changes were found in fish plasma, including increases in creatine kinase, lactate dehydrogenase, ammonia, glucose, aspartate aminotransferase and alanine aminotransferase levels. A decline of about 50% in lysozyme activity was observed by the end of the experimental period. Moreover, a marked increase in ceruloplasmin activity was detected 24 h after the end of intoxication with a subsequent decrease in its activity after 72 h and 5 days. This study concludes that not only consumption of food containing toxins but also MCs dissolved in water may pose a threat to fish health. Additionally, detected changes in lysozyme and ceruloplasmin activity may have distinct effects in fish resistance against pathogens or oxidative stress, which should be taken into account in the future studies.

Toxicity of cyanobacterial bloom in the eutrophic dam reservoir (Southeast Poland).

Cyanobacterial bloom was observed in a highly eutrophic dam reservoir, Zemborzycki, near Lublin (SE Poland) over a warm period in the year 2007. The water bloom consisted of several cyanobacterial taxa: Anabaena circinalis, Anabaena spiroides, Anabaena flos-aquae, Planktothrix agardhii, Aphanizomenon flos-aquae, Aphanizomenon gracile, and Microcystis flos-aquae. Anabaena spp., and Aphanizomenon spp., potential producers of neurotoxic anatoxin-a, quantitatively predominated in the studied bloom. High-performance liquid chromatography (HPLC) analysis of surface scum sampled during Anabaena circinalis domination revealed the presence of anatoxin-a at a high concentration (1,035.59 microg per liter of surface scum). At the same time, neither gas chromatography/mass spectrometry (GC/MS) nor microcystin enzyme-linked immunosorbent assay (ELISA) test showed the presence of other frequently found cyanotoxins, microcystins. Toxicity of cyanobacterial bloom was assessed by the crustacean acute toxicity test Daphtoxkit F pulex using Daphnia pulex, and by the chronic toxicity test Protoxkit F with a ciliate protozoan Tetrahymena thermophila. The crude extract of cyanobacterial scum showed high toxicity for Daphnia pulex, with 24-h median effective concentration (EC50) value of 90.3 microg/L of anatoxin-a, which corresponded to the cyanobacterial density in the scum of 1.01 g dry weight/L. For Tetrahymena thermophila, 24-h EC50 was lower, evaluated to be 60.48 microg/L of anatoxin-a, which corresponded to a cyanobacterial density of 0.68 g dry weight/L of the scum. On the basis of evaluated toxicity units, the cyanobacterial extract was classified at class IV toxicity, which means high toxic hazard.

Microcystin-LR modulates selected immune parameters and induces necrosis/apoptosis of carp leucocytes.

Microcystins (MCs) are potent hepatotoxins acting by the inhibition of protein phosphatase 1 and 2A, and may promote liver tumors. Moreover, studies also suggest they are nephrotoxic. The aim of the present study was to assess possible in vitro effects of microcystin-LR (which contains the amino acids leucine and arginine, the most widely studied and distributed variant of all microcystins) on the selected immune functions of the cells isolated from the head kidney of carp. In the experiments, pure microcystin-LR (MC-LR), was used at concentrations of 0.01, 0.1, 0.5, and 1 microg/ml RPMI-1640 medium. Leucocytes (lymphocytes and phagocytes) were isolated by centrifugation on a density gradient. Lymphocyte proliferation, intracellular production of reactive oxygen species by phagocytes, and the presence of apoptotic and/or necrotic cells were assessed. The respiratory burst activity of phagocytic cells was increased at the lowest toxin concentration used in the study, but it was decreased at higher concentrations. Using a sensitive luminescent immunoassay, MC-LR was observed to have no influence on the T-cell proliferation but decreased the proliferation of B lymphocytes. Moreover, it was noted that MC-LR induced necrosis to a higher degree than apoptosis in fish leucocytes. The results of the present study suggest the modulatory potency of microcystin-LR on fish leucocytes.

In vitro effects of pure microcystin-LR on the lymphocyte proliferation in rainbow trout (Oncorhynchus mykiss).

The aim of this study was to determine the in vitro influence of microcystin-LR on the viability and mitogenic response of rainbow trout (Oncorhynchus mykiss) lymphocytes since few data are available in the literature on the influence of cyanotoxins on fish immunocompetent cells. Lymphocytes were isolated from blood and haematopoietic organs (pronephros and spleen) and cultivated in RPMI 1640 medium with different concentrations of the toxin (1, 5, 10, 20, 40 mg ml-1 of cell suspension). Dose-dependent effects of microcystin-LR on the lymphocyte viability were shown. The lymphocyte proliferation was inhibited after application of microcystin at a concentration of 40 mg ml-1 but significantly increased at a concentration of 1mg ml-1 in comparison to the control group. The results suggest the modulatory effects of microcystin-LR dependent on the applied concentration.

Uptake of cadmium ions in white-rot fungus Trametes versicolor: effect of cd (II) ions on the activity of laccase.

The effects of cadmium Cd (II) ions on the physiology and biological activity of Trametes versicolor, a strain belonging to white-rotting Basidiomycetes, were examined. Cd (II) ions were added to 10-day-old cultures grown on a liquid medium, or at the time of inoculation. Our experiments showed that T. versicolor is a good cadmium biosorbent from aqueous solution, this strain removing almost all the Cd (ll) ions over the first 2h of incubation by what appears to be a rapid, energy-independent surface binding phenomenon, at the rate of approximately 2mg Cd per g mycelial dry weight. An additional slower and energy-dependent transport mechanism was also present, taking in approximately 0.3mg Cd (II) perg dry weight. It is also shown that these Cd (II) ions significantly stimulate the activity of extracellular laccase when added to 10-day-old cultures.