Effect of silver nanoparticles on the acute toxicity of mercury in Zebrafish (Danio rerio)

It is important to evaluate the co-exposure effects of chemical contaminants on aquatics. Mercury ions and silver nanoparticles are among the chemicals mixed together through amalgamation. This study was aimed to evaluate the effect of the presence of a non-lethal concentration of silver nanoparticles in water on the acute toxicity of inorganic mercury in zebrafish. In the presence or absence of silver nanoparticles, therefore, median lethal concentrations (LC50) of mercury were calculated according to the OECD standard guideline. The comparison of LC50s showed that the presence of 0.1 mg silver nanoparticles per liter, reduces the acute toxicity of mercury in the zebrafish by 1.5-fold (LC50 increased from 0.135 ± 0.010 to 0.206 ± 0.002 mg/L). Although the reduction of mercury toxicity in the presence of silver nanoparticles is probably due to the reduction of its bioavailability as a result of amalgamation or adsorption of mercury ions on the surface of nanoparticles, but further studies are needed to understand the exact mechanism of interaction between mercury and silver nanoparticles in aquatic environment

Production of all-female rainbow trout (Oncorhynchus mykiss) using sex-reversed males and investigation of their growth parameters in the first year of culture

Possibility of producing all-female rainbow trout (Oncorhynchus mykiss) using neomale stock were investigated in Kelardasht hatchery. To do this, we compared the fertilization, hatching rate and growth parameters of progeny in the first year of culture. Histological studies of gonads showed that progenies produced by mating sex-reversed males and normal females were totally female. Eyed-stage egg, hatching and early survival rate in all of female population were 90:69 %, 97.36 %, 91.49 % and in mix sex population were 7024 %, 98.22 %, 90.73 %, respectively, showing no significant differences (P>0.05). Lack of maturation in the first year cultured fish led to the identical growth parameters in mix sex and all-female groups (P>0.05). Results showed that use of sex-reversed males can be one of the best and successful methods of producing all-female populations

Toxicity comparison of silver nanoparticles synthesized by physical and chemical methods to tadpole (Rana ridibunda)

One of the possible threats in increasing use of nanomaterials is the emergence of toxicity in humans and other animals which is discussed in nanotoxicology. In addition to toxic effects of nanomaterials themselves, different chemical precursors which are usually used in bottom-up approaches for production of nanomaterials may have secondary toxic effects in living organisms. In contrast, less use of chemicals in top-down approaches may reduce these secondary effects. To test this hypothesis, toxic effects of two types of silver nanoparticles (AgNPs) produced by physical (top-down) and chemical (bottom-up) methods were investigated and compared on the tadpole, Rana ridibunda survival. The estimated 48 h LC50 values of AgNPs produced by chemical and physical methods for tadpoles were 0.055 ± 0.004 and 0.296 ± 0.085 mg.L-1, respectively. No observed effect concentration, lowest observed effect concentration, maximum acceptable toxicant concentration and median lethal concentration of AgNPs produced by chemical method were respectively 3.42, 4.50, 4.84 and 5.38 times less than those produced by physical method. Therefore, approving the mentioned hypothesis, it was revealed that AgNPs produced by chemical method are more toxic than those generated by physical method. However, it seems totally that AgNPs regardless of the method used for their production, have toxic effects on aquatic organisms and so, inhibiting their accidental or intentional entrance into the aquatic ecosystems should be more considered

Study on accumulation potential of zinc oxide nanoparticles in Artemia and its trophic transfer to Zebrafish (Danio rerio)

Although nanomaterials have broad applications in many fields including aquaculture, their release into the environment has raised some concerns in recent years. This study was conducted to investigate the possibility of enriching Artemia with zinc oxide nanoparticles (ZnO-NPs) for possible use in aquaculture on the one hand, and, on the other hand, to investigate the transfer of this material through the food chain and its accumulation in the body of zebrafish as an aquatic model. In order to evaluate the absorption and excretion of ZnO-NPs in Artemia, nauplii were exposed to concentrations of 1, 10 and 100 mg/L ZnO-NPs suspension for 24 hours and then placed in the nanoparticles-free water for another 24 hours. The zebrafish were then fed with ZnO-NPs enriched nauplii for 21 days, followed by feeding on nanoparticles-free nauplii for 7 days to determine trophic transfer as well as excretion of nanoparticles from the fish body. The accumulated zinc over the periods of absorption and excretion in nauplii and fish were measured using atomic absorption spectrophotometer. The results showed that Artemia nauplii had high potential for accumulation of ZnO-NPs, while accumulated zinc had high potential for transfer to fish. Based on the results, Artemia can be enriched with ZnO-NPs so that the needs of fish to zinc can be met. However, the risk of nanomaterials release into the aquatic ecosystems and their trophic transfer along the food chain should be considered

Effects of waterborne ZnO nanoparticles and Zn2+ions on the gills of rainbow trout (Oncorhynchus mykiss): Bioaccumulation, histopathological and ultrastructural changes

The aim of this study was comparing the toxic effects of zinc oxide nanoparticles (ZnO NPs) versus zinc ions (Zn2+) at a high non-lethal (500μg/L) and a low environmental relevant (0.05μg/L) concentrations on gills of rainbow trout (Oncorhynchus mykiss) following 14 days of waterborne exposure. Structural alterations, histopathological anomalies, and zinc bioaccumulation were investigated in the gills using field emission scanning electron microscopy (FESEM), hematoxylin and eosin staining (H&E), and graphite furnace atomic absorption spectrophotometry (GFAAS) respectively. Some damages such as shortening and fusion of secondary lamellae, surface epithelium hypertrophy, and hyperplasia of the primary lamellae were observed in the gill tissue. Histopathological alterations of gills were minimum in both 659777250 exposed (control) fish and fish exposed to 0.05μg/L Zn2+. The severity of gill damages were higher in fish exposed to 500μg/L ZnO NPs compared to 500μg/L Zn2+and 0.05μg/L ZnO NPs. The Zn accumulation in the gills was concentration-dependent such that bioaccumulation order was as 500μg/L Zn2+> 500μg/L ZnO NPs � 0.05μg/L Zn2+> 0.05μg/L ZnO NPs> control. In summary, the results of present study showed that although the accumulation capability of Zn2+was higher than ZnO NPs, but NPs cause more structural damages to gills compare to ions. © 2018, Central Fisheries Research Inst. All rights reserved

Effects of waterborne ZnO nanoparticles and Zn2+ions on the gills of rainbow trout (Oncorhynchus mykiss): Bioaccumulation, histopathological and ultrastructural changes

The aim of this study was comparing the toxic effects of zinc oxide nanoparticles (ZnO NPs) versus zinc ions (Zn2+) at a high non-lethal (500μg/L) and a low environmental relevant (0.05μg/L) concentrations on gills of rainbow trout (Oncorhynchus mykiss) following 14 days of waterborne exposure. Structural alterations, histopathological anomalies, and zinc bioaccumulation were investigated in the gills using field emission scanning electron microscopy (FESEM), hematoxylin and eosin staining (H&E), and graphite furnace atomic absorption spectrophotometry (GFAAS) respectively. Some damages such as shortening and fusion of secondary lamellae, surface epithelium hypertrophy, and hyperplasia of the primary lamellae were observed in the gill tissue. Histopathological alterations of gills were minimum in both 659777250 exposed (control) fish and fish exposed to 0.05μg/L Zn2+. The severity of gill damages were higher in fish exposed to 500μg/L ZnO NPs compared to 500μg/L Zn2+and 0.05μg/L ZnO NPs. The Zn accumulation in the gills was concentration-dependent such that bioaccumulation order was as 500μg/L Zn2+> 500μg/L ZnO NPs � 0.05μg/L Zn2+> 0.05μg/L ZnO NPs> control. In summary, the results of present study showed that although the accumulation capability of Zn2+was higher than ZnO NPs, but NPs cause more structural damages to gills compare to ions. © 2018, Central Fisheries Research Inst. All rights reserved

Histopathological alterations in the gill of zebrafish (Danio rerio) exposed to Cr and Ba doped TiO2 nanoparticles

In order to improve the photocatalytic efficiency of titanium dioxide, doping it with metals has been suggested; however, toxicity studies of metal-doped nanoparticles on aquatic organisms are not completely known. Therefore, the purpose of this study was to evaluate the short term effect of exposure to Cr and Ba doped TiO2 nanoparticles (NPs) using gill histopathology of zebrafish (Danio rerio) under laboratory condition. In this study, four concentration levels, 1, 10, 32, and 100 mg L-1 of each Cr and Ba doped TiO2 NPs as well as a control group were used. After 4 days of exposure, from each experimental group, three samples of fish gill prepared to study the classic histology (haematoxylin - eosin). The results of this study showed that the Cr and Ba doped TiO2 NPs can cause gill alterations including aneurism, dilated and clubbed tips, hyperplasia, oedema, curvature, fusion of lamellae, increase of mucous secretion, and proliferation in the erythrocytes of cartilaginous core. The extent of tissue damages increased by concentration levels of NPs; however, the severity of injouries caused by Cr was more notable than that of observed by Ba. © 2016 BIOFLUX SRL. All rights reserved

Scintillation Counters for the D0 Muon Upgrade

We present the results of an upgrade to the D0 muon system. Scintillating counters have been added to the existing central D0 muon system to provide rejection for cosmic ray muons and out-of-time background, and to provide additional fast timing information for muons in an upgraded Tevatron. Performance and results from the 1994-1996 Tevatron run are presented.Comment: 30 pages, 25 postscript figure