The effects of dietary exposure to Magnéli phase titanium suboxide and titanium dioxide on rainbow trout (Oncorhynchus mykiss).

Magnéli phase titanium suboxides (Magnéli TiOx) are promising, novel materials with superior properties compared to TiO2, they are substoichiometric titanium oxides with the chemical formula TinO2n-1 (where n ≥ 1). In this study, for the first time, subchronic effects of dietary intake of Magnéli TiOx were evaluated and compared with TiO2 particles of similar size, in concentrations 0.1% and 0.01% of feed. The experiment consisted of 38 d of an exposition period and 14 d of a depuration period. Minor effects on plasma biochemical profile and morphological parameters were recorded. A reduced count of leukocytes was found in the blood of both Magnéli TiOx and TiO2 exposed fish, suggesting immunotoxic effects. Erythrocytosis was specific for Magnéli TiOx. Indices of oxidative stress, namely increased lipid peroxidation in liver, increased activity of superoxide dismutase in liver, kidney and gills and glutathione S-transferase (GST) in gills, as well as decreased activity of ceruloplasmin and GST in liver were found predominantly in fish exposed to TiO2. Histopathological examination revealed increased lipid-like vacuolation in the liver, the presence of hyaline droplets in renal tubules and multiplication of mucous glands in the epidermis in both tested substances and intestine damage in TiO2 groups. Overall, in Magnéli TiOx exposed groups, fewer adverse effects compared to TiO2 expositions were recorded. Their wider practical implementation in place of TiO2 is therefore beneficial.

Comprehensive fitness evaluation of common carp (Cyprinus carpio L.) after twelve weeks of atrazine exposure.

Atrazine is frequently detected in surface waters and negatively affect physiological function in aquatic organisms. Even though numerous authors have intensively studied its toxicity, only limited information concerning the long-term fish exposure is available. The aim of this study was evaluation of chronic exposure in common carp. Fish were exposed to a range of atrazine concentrations (0.3 - environmentally relevant concentration; 300; 1000; and 3000 µg/l) for twelve weeks. The potential impact of atrazine exposure was studied using various markers (behaviour; biometrical characteristics; haematological, biochemical and oxidative stress indices and histopathological changes). Most alterations were recorded at the highest concentration (3000 µg/l) which is probably due to a combined effect of both the herbicide exposure and intensive parasite infection development during second week. This group was cancelled after three weeks due to adverse health status, which partly confirmed atrazine immunotoxicity. Chronic exposure resulted in long-term reduction in feed intake followed by a significant decrease in body weight and morphological changes in gill at 1000 µg/l. At the same concentration, significant alterations in haematological (e.g. increase in erythrocyte, leukocyte, lymphocytes and neutrophil counts as well as decrease in monocyte counts) and biochemical (e.g. changes in enzyme activities; increase in glucose; decrease in ammonia) indices were documented, especially during first three weeks. Similar trend, but not so intensive, was observed at 300 µg/l. Moreover, significant changes were observed in various indicators of oxidative stress. These alterations were highly variable with both increasing and decreasing trends depending on dose and analysed tissue. Significant changes, especially in white blood profile, enzyme activities and oxidative stress indices, were proven even at 0.3 µg/l. Obtained results indicate that chronic atrazine exposure of common carp can negatively influence many indicators of health status such as behaviour, immune response, haematological and biochemical profile, oxidative stress indices and organ histopathology.

The effects of a therapeutic formalin bath on selected immunological and oxidative stress parameters in common carp (Cyprinus carpio).

Formalin is commonly used as a component of antiparasitic baths in fisheries. In this study the impact of this bath on the immune profile and oxidative stress parameters was evaluated. A formalin bath was prepared in the concentration of 185.3 mg L-1 (0.17 mL L-1) at a temperature of 20 °C. A total of 96 common carp Cyprinus carpio (Linnaeus, 1758) individuals were immersed in this bath for 60 min. The effects were monitored immediately, and then after 24, 48 h and 10 days following the treatment. The study revealed the most effects 10 days after the treatment, when we observed the decrease of lysozyme in skin mucus, the decrease of anti-inflammatory cytokine transforming growth factor beta in gill tissue and increase of interleukin 10 in cranial kidney tissue. The pro-inflammatory cytokine interleukin 1b showed an increase in gill tissue immediately after the bath and the increase in glutathione peroxidase in gill tissue was also observed 24 h and 10 days after bath treatment. The other investigated parameters did not show any significant changes. In conclusion, even though the formalin bath elevated some parameters as mentioned above, formalin used in the bath is probably safe as an antiparasitic treatment of fish.

Sodium chloride treatment effects on rainbow trout suffering from proliferative kidney disease caused by Tetracapsuloides bryosalmonae.

The aim of the present study was to evaluate the effect of a long-term sodium chloride bath on rainbow trout Oncorhynchus mykiss naturally infected by Tetracapsuloides bryosalmonae. A total of 106 infected fish were divided into 2 groups. One group was left untreated and the other was treated with sodium chloride in increasing doses up a concentration of 0.8%. After 14 d, treatment was stopped and for a further 7 d the fish response to the sodium chloride bath was observed. Cumulative mortality was significantly lower in the treated group (19.2%) compared to the untreated group (31.5%) after 21 d. This corresponded to the lower but non-significant parasite intensity in kidney and spleen in the treated group after 14 d of treatment. However, lower prevalence of parasites in both tissues was recorded in the untreated group after 21 d of treatment, but a significant difference was observed only in spleen tissue. Furthermore, significant increases in leukocytes, hemoglobin, haematocrit, ferric reducing ability of plasma, and ceruloplasmin, and significant decreases in alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase activities were noticed in the treated group compared to the untreated group. In contrast, significant decreases in lysozyme concentration in the mucus and phagocyte oxidative burst in the blood were observed in the treated group. Histopathological examination revealed proliferative and reparative changes in parenchymatous tissues in the treated group. The 14- and 21-d salt bath used in rainbow trout with proliferative kidney disease was associated with a reduction in mortality and enhanced the reparative phase in the treated group.

Multibiomarker Responses of Juvenile Stages of Zebrafish (Danio rerio) to Subchronic Exposure to Polycyclic Musk Tonalide.

Synthetic polycyclic musks, widely used as additives in personal care products, are present in both biotic and abiotic matrices of the aquatic environment at concentrations of ng/l to µg/l. Although they are determined at comparatively low concentrations, these levels are biologically relevant and pose a significant growing risk as stressors to aquatic organisms. The purpose of our study was to evaluate the effects of 28-day-long exposure to polycyclic musk tonalide in zebrafish juvenile stages (Danio rerio) using selected biomarkers. Environmentally relevant concentrations of tonalide caused significant changes in selected enzyme activities in the experimental groups exposed to the highest concentrations. The activity of glutathione S-transferase and lipid peroxidation increased significantly (p < 0.05) after exposure to the highest concentration (50,000 ng/l) compared with the control. A similar trend was observed in catalase activity; there was a significant increase (p < 0.05) after exposure to two highest concentrations of tonalide (5000 and 50,000 ng/l). In addition, a statistically significant decrease (p < 0.05) in glutathione reductase activity was found in the lowest test concentration of tonalide (50 ng/l). None of the tested concentrations resulted in histopathological changes in liver, kidney, skin, or gill. Furthermore, no effects on body weight, body length, specific growth rate, and behavior were observed. Our results showed that tonalide exposure induced profound changes in the activities of antioxidant and detoxifying enzymes, such changes representing an adaptive response of the fish organism to tonalide toxicity.