Effect of Silymarin Supplementation on Nickel Oxide Nanoparticle Toxicity to Rainbow Trout (Oncorhynchus mykiss) Fingerlings: Pancreas Tissue Histopathology and Alkaline Protease Activity

Supplementation of Siberian sturgeon (Acipenser baerii) diet with different zinc sources: effects on growth performance, digestive enzymes activity, hemato-biochemical parameters, antioxidant response and liver histology

An 8-week feeding trial was carried out to examine the effect of different sources of dietary Zn on some physiological responses (performance, digestive enzymes activity, hemato-biochemical parameters, antioxidant status and liver histology) of Siberian sturgeon, Acipenser baerii. For this purpose, fish with an average weight of 100 g ± 5 were randomly allocated into four groups including control, inorganic zinc (Zn-sulfate), organic zinc (Zn-gluconate), and zinc-oxide nanoparticles (ZnO-NPs) at 50 mg Zn kg- 1 feed. Improved growth indices, namely weight gain (WG) and specific growth rate (SGR) and feed conversion ratio (FCR) were observed in fish fed Zn-gluconate supplemented diet (P < 0.0.5). The highest digestive enzymes activity was recorded in fish fed Zn-gluconate supplementation (P < 0.0.5). Hematological indices significantly increased in fish fed diet containing ZnO-NPs (P < 0.0.5). Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) of fish fed ZnO-NPs contained diet were the highest (P < 0.0.5). The highest serum superoxide dismutase (SOD) and catalase (CAT) enzymes activity were observed in fish fed ZnO-NPs and inorganic/organic Zn contained diets, respectively. While liver tissue SOD and glutathione peroxidase (GPx) enzymes activity Zn were significantly increased in fish fed inorganic/organic Zn supplemented diet (P < 0.0.5). Based on liver histological results, a severe tissue changes such as necrosis and pyknosis were observed in fish fed with Zn-sulfate in comparison to other forms. In conclusion, the data of the present study confirmed that organic Zn (mainly) and nano-Zn (to some extent) could be more efficient Zn sources in Siberian sturgeon.

The physiological responses to titanium dioxide nanoparticles exposure in pearl oysters (Pinctada fucata martensii)

To evaluate the physiological responses to titanium dioxide nanoparticles exposure in pearl oysters (Pinctada fucata martensii), pearl oysters were exposed for 14 days to different levels (0.05, 0.5, and 5 mg/L) of nano-TiO2 suspensions, while a control group did not undergo any nano-TiO2 treatment. And then recovery experiments were performed for 7 days without nano-TiO2 exposure. At days 1, 3, 7, 14, 17, and 21, hepatopancreatic tissue samples were collected and used to examine the activities of protease, amylase, lipase, catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), lysozyme (LYS), alkaline phosphatase (AKP), and acid phosphatase (ACP). The microstructure of the nacreous layer in shell was also analyzed by scanning electron microscopy. Results showed that pearl oysters exposed to 5 mg/L of TiO2 nanoparticles had significantly lower protease, amylase, and lipase activities and significantly higher CAT, SOD, GPx, LYS, ACP, and AKP activities than control pearl oysters did even after 7-day recovery (P-values <0.05). Pearl oysters exposed to 0.5 mg/L or 0.05 mg/L of TiO2 nanoparticles had lower protease, amylase, and lipase activities and higher CAT, SOD, GPx, LYS, ACP, and AKP activities than control pearl oysters did during the exposure period. After 7-day recovery, no significant differences in protease, lipase, SOD, GPx, CAT, ACP, AKP, or LYS activities were observed between pearl oysters exposed to 0.05 mg/L of TiO2 nanoparticles and control pearl oysters (P-values >0.05). In the period from day 7 to day 14, indistinct and irregular nacreous layer crystal structure in shell was observed. This study demonstrates that TiO2 nanoparticles exposure influences the levels of digestion, immune function, oxidative stress, and biomineralization in pearl oysters, which can be partially and weakly alleviated by short-term recovery. These findings contribute to understanding the mechanisms of action of TiO2 nanoparticles in bivalves. However, studies should evaluate whether a longer recovery period can restore to their normal levels in the future.

Physicochemical and Biochemical Properties of Trypsin-like Enzyme from Two Sturgeon Species

This work aimed to determine the physicochemical and biochemical properties of trypsin from beluga Huso huso and sevruga Acipenser stellatus, two highly valuable sturgeon species. According to the results obtained from the methods of casein-zymogram and inhibitory activity staining, the molecular weight of trypsin for sevruga and beluga was 27.5 and 29.5 kDa, respectively. Optimum pH and temperature values for both trypsins were recorded at 8.5 and 55 °C by BAPNA (a specific substrate), respectively. The stability of both trypsins was well-preserved at pH values from 6.0 to 11.0 and temperatures up to 50 °C. TLCK and SBTI, two specific trypsin inhibitors, showed a significant inhibitory effect on the enzymatic activity of both trypsins (p < 0.05). The enzyme activity was significantly increased in the presence of Ca⁺² and surfactants and decreased by oxidizing agents, Cu⁺², Zn⁺², and Co⁺² (p < 0.05). However, univalent ions Na⁺ and K⁺ did not show any significant effect on the activity of both trypsins (p > 0.05). The results of our study show that the properties of trypsin from beluga and sevruga are in agreement with data reported in bony fish and can contribute to the clear understanding of trypsin activity in these primitive species.

Impact of Nickel Oxide Nanoparticles (NiO) on Oxidative Stress Biomarkers and Hemocyte Counts of Mytilus galloprovincialis

In this study, the toxic effects of nickel oxide nanoparticles (NiO-NPs) on the model organism Mediterranean mussel (Mytilus galloprovincialis) gill, digestive gland, and hemolymph tissues for 96 h were investigated. Lipid peroxidation (MDA) determination was performed to reveal the oxidative stress generation potential of nanoparticles, and superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione-S-transferase (GST) enzyme levels were measured to determine antioxidant responses. Lysosomal membrane stability and total hemocyte counts were performed to determine cytotoxic effects. All parameters were altered in different concentrations of NiO-NPs (2, 20, and 200 mg L^-1). The SOD levels increased depending on the concentration (p < 0.05), and the increases in CAT, GPx, and GST levels were lower at 20 mg L^-1 concentration (p < 0.05). There was a slight difference between the exposure and the control groups in terms of GR enzyme. The MDA level increased in parallel with the concentration (p < 0.05), the stability of the cell membrane (p < 0.05), and the number of hemocyte cells decreased as a result of exposure (p < 0.05). The results emphasize that NiO-NPs may have negative effects on the aquatic environment.

Dietary silymarin, Silybum marianum extract ameliorates cadmium chloride toxicity in common carp, Cyprinus carpio

The present study evaluated the protective effects of silymarin extract (SIE) on cadmium chloride toxicity in common carp, Cyprinus carpio. Four experimental group were considered for the experiment including: SIE0 (control): non-SIE-supplemented fish, SIE1: fish supplemented with 400 mg SIE/kg diet, SIE2: fish supplemented with1400mg SIE/kg diet, SIE3: fish supplemented with 2400 mg SIE/kg diet). Fish were fed experimental diet for 60 days and then exposed to cadmium chloride (1.5 mg/l or 25% of LC50–96 h) and antioxidant defense components and the survival rate assayed. After 60 days feeding trial, total antioxidant capacity (TAC) levels significantly increased (P<0.01) in 1400–2400 mg SIE/kg diet treatments compared to those in control and 400 mg SIE/kg diet treatment. Malondialdehyde (MDA) (P>0.01) and acetylcholinesterase (AChE) levels (P>0.01) remained unchanged during the feeding period in all treatments. Hepatic catalase (CAT) in all SIE supplemented groups and superoxide dismutase (SOD) and glutathione peroxidase (GPx) in 1400–2400 mg SIE/kg diet treatments significantly elevated (P<0.01) in response to SIE. Plasma levels of hepatic metabolic enzymes [alanine transaminase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), creatine kinase (CK), lactate dehydrogenase (LDH) ] remained unchanged (P>0.01) in all experimental groups over feeding period. After exposure to cadmium chloride, TAC levels were significantly elevated (P<0.01) in all experimental groups. In control and 400 mg SIE/kg diet treatment, TAC showed lower levels (P<0.01) compared to other groups. MDA levels were significantly increased (P<0.01) in control and fish supplemented with 400 and 1400 mg SIE/kg diet. TAC in the fish of 2400 mg SIE/kg diet treatment remained unchanged (P>0.01), following the exposure. CAT (P<0.01), SOD (P<0.01) and GPx (P<0.01) were significantly elevated in response to cadmium chloride in all groups. However, the treatments, 1400 and 2400 mg SIE/kg diet, showed lower increases (P<0.01) of enzymes. AChE activity (P<0.01) in the liver were significantly decreased in control and fish fed 400 and 1400 mg SIE/kg diet. Exposure to cadmium significantly increased (P<0.01) the plasma levels of ALT, AST, ALP and LDH in control and those fed 400 and 1400 mg SIE/kg diet. The findings of the current study indicated that SIE at a rate of 1400–2400mg/kg diet might enhance antioxidant defense and protect hepatocytes against toxic effects of cadmium.

Toxicity of Nanoparticulate Nickel to Aquatic Organisms: Review and Recommendations for Improvement of Toxicity Tests

We reviewed the literature on toxicity of nanoparticulate nickel (nano-Ni) to aquatic organisms, from the perspective of relevance and reliability in a regulatory framework. Our main findings were 1) much of the published nano-Ni toxicity data is of low or medium quality in terms of reporting key physical-chemical properties, methodologies, and results, compared with published dissolved nickel studies; and 2) based on the available information, some common findings about nanoparticle (NP) toxicity are not supported for nano-Ni. First, we concluded that nanoparticulate elemental nickel and nickel oxide, which differ in chemical composition, generally did not differ in their toxicity. Second, there is no evidence that the toxicity of nano-Ni increases as the size of the NPs decreases. Third, for most organisms tested, nano-Ni was not more toxic on a mass-concentration basis than dissolved Ni. Fourth, there is conflicting evidence about whether the toxicity is directly caused by the NPs or by the dissolved fraction released from the NPs. However, no evidence suggests that any of the molecular, physiological, and structural mechanisms of nano-Ni toxicity differ from the general pattern for many metal-based nanomaterials, wherein oxidative stress underlies the observed effects. Physical-chemical factors in the design and conduct of nano-Ni toxicity tests are important, but often they are not adequately reported (e.g., characteristics of dry nano-Ni particles and of wetted particles in exposure waters; exposure-water chemistry). Environ Toxicol Chem 2020;39:1861-1883 © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.