The cerium oxide nanoparticles toxicity induced physiological, histological and biochemical alterations in freshwater mussels, Unio crassus.

INTRODUCTION: Releasing of cerium oxide nanoparticles (nano-CeO2) to the nature has increased due to the widespread use in many fields ranging from cosmetics to the food industry. Therefore, nano-CeO2 has been included in the Organization for Economic Co-operation and Development's (OECD) priority list for engineering nanomaterials. In this study, the effects of nano-CeO2 on the freshwater mussels were investigated to reveal the impact on the freshwater systems on model organism. METHODS: First, the chemical and structural properties of nano-CeO2 were characterized in details. Second, the freshwater mussels were exposed to environmentally relevant concentrations of nano-CeO2 as 10 mg, 25 mg and 50 mg/L during 48-h and 7-d. Third, after the exposure periods, hemolymph and tissue samples were taken to analyse the Total Hemocyte Counts (THCs) histology and oxidative stress parameters (total antioxidant status, glutathione, glutathione-S-transferase, and advanced oxidative protein products). RESULTS: Significant decrease of the THCs was observed in the nano-CeO2 exposed mussels compared to the control group (P < 0.05). The histological results showed a positive association between nano-CeO2 exposure concentration in the water and level of tissue damage and histopathological alterations were detected in the gill and the digestive gland tissues. Oxidative stress parameters were slightly affected after exposure to nano-CeO2 (P > 0.05). In conclusion, this study showed that acute exposure of freshwater mussels to nano-CeO2 did not pose significant biological risk. However, it has been proven that mussels are able to accumulate nano-CeO2 significantly in their bodies. CONCLUSION: This suggests that nano-CeO2 may be a potential risk to other organisms in the ecosystem through trophic transfer in the food-web based on their habitat and niche in the ecosystem.

Environmental pollutant sodium omadine: toxic effects in zebra fish (Danio rerio).

In recent years one of the most striking results of over-population and consumption activities in the world is the rapid increase in environmental pollutants. Environmental pollutants, one of the harmful consequences of technological and modern life, threaten the health of people and other living organisms. In this study, we aimed to determine the effects of sodium omadine (NaOM) on superoxide dismutase enzyme (SOD) activity as an antioxidant and on 8-OHdG levels as oxidative DNA damage in zebrafish. Zebrafish, obtained from the aquarium fish producer, were stocked in experimental aquariums to ensure their adaptation period to the experimental conditions 15 days before the experiment. The fish were exposed to 1 ug/L and 5 ug/L concentrations of NaOM for 24, 72, and 96 h. SOD enzyme activity (U/100 mg tissue) and 8-OHdG (pg/100 mg tissue) were measured using commercial kits. The statistically significant differences in tissue SOD levels and data for DNA damage between the groups were determined as time and dose-dependent (p < 0.05). Biocidal products are environmental pollutants that cause changes in antioxidant enzyme activities, especially in non-target organisms. Marine pollution and the degradation of ecosystems directly affect people, and the results of the study offer awareness of health problems, environmental pollution, and marine pollution.

How do biocidals affect the non-target marine organisms: the short-term effects of antifouling agent sodium pyrithione on Mediterranean mussels (Mytilus galloprovincialis, Lamark 1819).

The metallic pyrithiones are used as antifouling paints for marine vehicles against fouling organisms. However, they are dissolved in marine water and have negative impacts on marine non-target organisms. This study evaluated the adverse effects of sodium pyrithione (NaPT) on Mytilus galloprovincialis using total hemocyte counts (THCs), oxidative stress and antioxidant parameters, and histopathological observations. Mussels were exposed to 0.1 and 1 µg/L NaPT for 96 h. The THC values of the NaPT-exposed mussels significantly decreased (p < 0.05). Lipid peroxidation and advanced oxidative protein products of digestive gland and gill tissues were decreased but only the digestive gland tissues of 0.1 µg/L NaPT values were significantly decreased compared to control groups (p < 0.05). Histological alterations were observed in the gill and the digestive gland tissues revealing malformations and hyperplasia of gill lamella; degenerations and loss of tubules of digestive gland after exposure to NaPT for 96 h. As a result, biocidal sodium pyrithione has adverse effects on the mussels even in short-term exposures and low concentrations.

Does persistent organic pollutant PFOS (perfluorooctane sulfonate) negative impacts on the aquatic invertebrate organism, Astacus leptodactylus [Eschscholtz, 1823].

Highly persistent perfluorooctane sulfonate (PFOS) is an industrial fluorinated organic chemical with significant bioaccumulation and biomagnification properties. The purpose of this study was to determine the toxic effects of sublethal PFOS on the aquatic invertebrate organism, narrow-clawed crayfish [Astacus leptodactylus Eschscholtz, 1823]. The 96 h LC50 value was determined as 48.81 mg/L (34.19-63.68 mg/L) with probit analysis. The sublethal experimental design was formed into four groups solvent control (DMSO, dimethyl sulphoxide), non-treated control group, and 1/10 (5 mg/L) and 1/100 (0.5 mg/L) of 96 h LC50 of PFOS, and crayfish were exposed for 48 h, 7 d, and 21 d under laboratory conditions. Total haemocyte counts (THCs) decreased, while the haemolymph total antioxidant status (TAS) values increased (p < 0.05) after exposure to 0.5 and 5 mg/L PFOS for 48 h, 7 d, and 21 d. Haemolymph total oxidative stress (TOS) levels significantly increased at 5 mg/L PFOS concentration (p < 0.05). Catalase (CAT) activities increased at both concentrations after 48 h and 7 d and then returned to control levels after 21 d; whereas superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities did not change in muscle tissue (p > 0.05). GPX and CAT activities decreased, but SOD activity increased in hepatopancreas tissue (p < 0.05). SOD activity at both concentrations and CAT activity at 5 mg/L PFOS exposure decreased in gill tissue, while GPX activity increased at both concentrations of 48 h and 7 d and returned to control values on day 21 of exposure. Histopathological alterations were detected in hepatopancreas and gill tissues. Lamellar deformations, epithelial hyperplasia, and haemocytic infiltrations were observed in the gill tissues, whereas tubular degeneration, tubule loss, necrosis, and lesions in the hepatopancreas tissues were the major recorded alterations. As a result, the sublethal concentrations of PFOS have toxic effects on crayfish and histologically cause tissue damage. Our findings also support a better understanding of the early toxicological effects of PFOS in freshwater ecosystems. Also, it could be concluded that A. leptodactylus is a reliable model for examining histopathological alterations and differences in enzyme activities together with the haemolymph findings in toxicology studies amid aquatic species.

Are BPA-free plastics safe for aquatic life? - Fluorene-9-bisphenol induced thyroid-disrupting effects and histopathological alterations in adult zebrafish (Danio rerio).

Fluorene-9-bisphenol (BPFL) is used as an alternative compound for bisphenol A, an endocrine disruptor compound which is present in various materials including plastic bottles and packaging. Although it is used extensively in products that are labelled BPA-free, its effect on wildlife and humans have not been fully studied. Therefore, this study aimed to investigate the effects of BPFL in adult zebrafish. In the preliminary experiments of the study, the median lethal concentration value (LC50) of BPFL was 0.25 mg/L (95 % confidence interval 0.15-0.41) for 96 h. Following exposure to three different sublethal concentrations of BPFL after 96 h and 15 days, T4 hormone levels, expression levels of genes involved in thyroid metabolism and histopathological alterations were assessed. T4 hormone levels were found to be significantly higher in females at the lowest BPFL concentration following 96 h exposure (P < 0.05). Expression levels of trh, tshba and trhrb genes were upregulated following 96 h exposure at 0.025 mg/L concentration and crh was upregulated following 15 days exposure at 0.025 mg/L concentration in female zebrafish (P < 0.05). The most prominent histopathological findings in zebrafish exposed to 0.025 and 0.125 mg/L of BPFL were observed in the gill, liver, kidney and testis tissues. The gill tissues showed some hyperemia, lamellar fusion, hyperplasia, epithelial lifting, and telangiectasis, while passive hyperemia, hydropic degeneration, and necrosis were observed in the liver tissues. The BPFL is highly toxic to zebrafish even in sublethal concentrations according to the molecular and histopathological responses.

The effects of invasive epibiont Dreissena polymorpha on the narrow-clawed crayfish (Astacus leptodactylus, Astacidae) in Egirdir Lake, Turkey: a case study.

In aquatic ecosystems, organisms are in a close relationship with each other. While this relationship is sometimes beneficial for both species, it can sometimes be harmful to one species. This study aimed to investigate the effects of colonized zebra mussels Dreissena polymorpha on the growth parameters and total hemocyte counts of the narrow-clawed crayfish Astacus leptodactylus from Egirdir Lake (Turkey). Zebra mussels were found on various body parts of crayfish and the most intense (44.7%) colonization was in the carapace region. There were significant differences between various biometric data and ratios of the narrow-clawed crayfish with epibiont D. polymorpha and without epibiont D. polymorpha (the control group) in terms of total length, abdomen width, arm length and chelae length, carapace width/carapace length, carapace length/abdomen length, abdomen width/carapace width, and chelae width/chelae length (p < 0.05). When the total hemocyte counts were examined, lower values ​were obtained in the narrow-clawed crayfish with zebra mussels compared to the control group (p < 0.05). As a result, epibiont organisms have negative effects on the health and growth status of the host organisms considering total hemocyte counts and biometric data.

Does bisphenol A bioaccumulate on zebrafish? Determination of tissue bisphenol A level.

Bisphenol A (BPA) is a high-production-volume industrial chemical mainly used in the production of polycarbonates and epoxy resins utilized in the manufacture of containers, bottles, toys, and medical devices. It has systemic effects as an endocrine disruptor even at low doses. To analyze its quantity in biological materials, sensitive and reproducible methods have to be used. Different doses and duration (90 and 900 µg/L, 24 and 120 h, and 21 days) of BPA exposure to whole body zebrafish were analyzed after specific homogenization of tissue, and then a modified method HPLC was used. The mobile phase was acetonitrile and water using a gradient method of reversed-phase C18 column, and excitation = 227 nm/emission = 313 nm. The calibration curve for BPA using HPLC-fluorescence detection method was between a concentration range of 1 and 1000 ng/mL and linear, and r2 = 0.999. The mean and standard error of mean values were 4.29 ± 1.05, 2.50 ± 0.92, and 2.53 ± 0.68 for control; 10.43 ± 2.61, 11.46 ± 3.24, and 8.55 ± 3.11 for BPA-90 µg/L; and 17.78 ± 4.39, 21.55 ± 4.37, and 25.32 ± 3.25 for BPA-900 µg/L (24 h, 120 h, and 21 days, respectively). Although some statistical significance among dose/time was observed between two different dose-treated groups, statistical significance was not found in dose/time results within the group. However, the positive result of BPA in the control group can be explained by low-dose, chronic exposure or prevalence of endocrine-disrupting chemicals.

How pollution effects the immune systems of invertebrate organisms (Mytilus galloprovincialis Lamark, 1819).

Hemocytes are the main immunologic parameters for invertebrate organisms as a response to diseases and pollutions. This study was aimed to reveal the relations between pollution and the total and differential hemocytes numbers. The gulf of Izmir was selected as location for sampling due to its contaminated by different anthropogenic pollutants mainly industrial effects. The effects of the pollutants were investigated on the mussels that have been collected from eight stations in the Izmir Bay (1- Inciralti, 2- Göztepe 3-Konak-4- Pasaport 5-Alsancak, 6-Karsiyaka, 7-Bostanli), which are known as the most polluted part of inner Bay of Izmir (Western Coast of Turkey) and 8-Foça, (an anthropogenically industrialized and shipping -impacted area). The pollution effects in the bay were determined on hemolymphs by biomarkers such as total hemocyte counts (THCs) and differential hemocyte counts (DHCs). Microscopic examinations have shown the statistical differences at THCs and DHCs. The highest total hemocyte number was determined in the station 7 (Bostanli) and the lowest in the station 4 (Pasaport) (P < 0.05). The number of total hemocyte counts were not differed significantly in the Stations among 2 (Göztepe), 5 (Alsancak) and 6 (Karsiyaka), and between Stations 8 (Foça) and 1 (Inciralti) (P > 0.05). In addition, there have been significant differences in subpopulation according to differential hemocyte numbers. The results indicate that the station 8 (reference site-Foça) has the highest agranulocyte number while station 7 (Bostanli) and the station 1 (Inciralti) have the lowest agranulocyte numbers (P < 0.05). As for the basophilic hemocyte numbers, this situation was reversed highest number in station 1 (Inciralti) and 7 (Bostanli) and lowest in the station 8 (Foça) (p < 0.05). The station 4 (Pasaport) has the highest eosinophilic hemocyte number while station 8 (Foça) has the lowest. We concluded that differential hemocytes counts are more sensitive as biomarker with the highest numbers of agranulocytes and lowest numbers of eosinophilic and basophilic hemocytes in reference site.

How does sublethal permethrin effect non-target aquatic organisms?

Permethrin is belonged to pyrethroids that are one of the substances developed as an alternative to pesticides. Permethrin, which is used especially in agriculture, can bioaccumulate in the water and sediment when mixed into aquatic ecosystems. For this reason, it is necessary to investigate the effect of this substance on aquatic organisms other than the target organism. The aim of this study was the determination of acute and sublethal effects as antioxidant enzyme levels on different organs and hemolymph biochemistry of the non-target aquatic organism, narrow-clawed crayfish (Astacus leptodactylus), after exposure to permethrin, one of the synthetic pyrethroid pesticides, contaminating aquatic ecosystems due to its increase usage. The invertebrate model organism, the narrow-clawed crayfish, was selected for its bioindicator role in food webs as planktivorous grazers epibenthic scavengers and good alternative models in ecotoxicology studies with the importance in conservation of freshwater ecosystems. The 96-h LC50 value of permethrin to experimental species was estimated as 0.903 µg/L (95% CI = 0.5042-2.2734 µg/L) with probit analysis method. The sublethal concentration of the permethrin was determined by 1/10 of 96-h LC50 values as 0.09 µg/L. There were two control (negative and acetone) groups in the experiment. The sampling of hemolymph and the tissues (gills, hepatopancreas, and muscle) were done 48 h and 96 h after exposure of the permethrin. The total hemocyte counts significantly increased in the 96-h exposed group of permethrin (p<0.05). Among the hemolymph biochemical parameters, the hemolymph potassium and chloride values increased statistically (p<0.05). Malondialdehyde levels (MDA) of gills and muscle were significantly increased, whereas the MDA level of the hepatopancreas was significantly decreased at the end of the experiment (p<0.05). Hyperplasia in the lamella was recorded in gills, while the degenerations of the hepatopancreas tissues were observed. According to obtained results, permethrin was extremely toxic as acutely to narrow-clawed crayfish and also effected at sublethal concentrations.