This study investigated the toxicity of polyethylene microplastics (MPs; <0.02 mm) and CuSO4, alone and in combination, on the freshwater crayfish Pontastacus leptodactylus. In this study, the crayfish were exposed to PE-MPs (0.0, 0.5, and 1 mg L^-1) and CuSO4·5H2O (0.0, 0.5, and 1 mg L^-1) for a period of 28 days. Next, multi-biomarkers, including biochemical, immunological, and oxidative stress indicators were analyzed. Results showed that co-exposure to PE-MPs and CuSO4 resulted in increased aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and decreased alkaline phosphatase (ALP), butyrylcholinesterase (BChE), and gamma-glutamyl-transferase (GGT). Triglycerides, cholesterol, glucose, and albumin content also increased. Although no significant change was observed in lysozyme and phenoloxidase activities in crayfish co-exposed to 0.5 mg L^-1 MPs and 0.5 mg L^-1 CuSO4, their activities were significantly decreased in other experimental groups. Oxidative stress parameters in hepatopancreas indicated increased superoxide dismutase (SOD), glutathione peroxidase (GPx), and in malondialdehyde (MDA) levels, but decreased catalase (CAT), glucose 6-phosphate dehydrogenase (G6PDH), and cellular total antioxidant (TAC). Results showed that the sub-chronic toxicity of CuSO4 was confirmed. The study confirmed the toxicity of CuSO4 and found that higher concentrations led to more severe effects. Co-exposure to PE-MPs and CuSO4 primarily compromised the endpoints, showing increased toxicity when both pollutants were present in higher concentrations. The activities of POX, LYZ, ALP, GGT, LDH, and CAT were suppressed by both CuSO4 and MPs. However, a synergistic increase was observed in other measured biomarkers in crayfish co-exposed to CuSO4 and MPs.

The omnipresence of microplastics and nanoparticles has led to their entry into the fresh and marine aquatic systems and affected the biota. The present study aims to evaluate the impact of the interaction of polyethylene microplastic (PE-MPs) and zinc oxide nanoparticles (ZnO-NPs) in mosquito fish, Gambusia holbrooki. For this, fish were exposed to 100 µg L⁻¹ PE-MPs (group 2), 200 µg L⁻¹ PE-MPs (group 3), 50 µg L⁻¹ ZnO-NPs (group 4), 50 µg L⁻¹ ZnO-NPs combined with 100 µg L⁻¹ PE-MPs (group 5), and 200 µg L⁻¹ PE-MPs (group 6) and control (group 1) for 14 days. The assessment was made through accumulation studies (MPs and Zn) and antioxidant assay. Significant elevation in the activity of catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase levels was observed in ZnO-NPs alone and in combination with PE-MPs (100 and 200 µg L⁻¹) groups only. High malondialdehyde levels were observed in all the exposed groups. Concordantly total antioxidant (TAN) levels displayed a significant reduction in all treated groups compared to control. Accumulation study on microplastic suggested liver-targeted accumulation of PE-MPs, while for ZnO-NPs, observed PE-MPs assisted accumulation. The study affirms the induction of oxidative stress and ZnO-NPs-induced toxicity facilitated by PE-MPs in fish.

The aim of this study is to evaluate the toxic effects of different concentrations of cigarette butt leachate (CBL) (0.0, 0.5, 1, 1.5, and 2.0 µL L^-1) on blood biochemistry, oxidative stress biomarkers, and the biochemical profile of the liver and muscle of Nile tilapia fish (Oreochromis niloticus) after 21 days. Increased activity of lactate dehydrogenase (LDH), gamma-glutamyl transferase (GGT), and aspartate aminotransferase (AST) in plasma, and decreased activity of alkaline phosphatase (ALP) in fish exposed to CBL, indicated cytotoxicity. Elevated cholesterol, triglycerides, and glucose levels, coupled with reduced total protein, albumin, and globulin levels in the plasma, indicated impaired liver function in the fish. An increase in creatinine showed kidney damage. Increased superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) activities, along with the decrease in liver glutathione (GSH) content and total antioxidant capacity in the hepatocytes of fish exposed to CBL, indicated the occurrence of oxidative stress. Malondialdehyde (MDA) elevation indicated heightened lipid peroxidation in CBL-exposed fish hepatocytes. Raman spectroscopy revealed altered biochemical profiles in fish liver and muscle post-CBL exposure. The results demonstrated that exposure to CBL led to a decrease in phospholipid levels, collagen destruction, changes in phenylalanine levels, and a decrease in the levels of lipids, proteins, and nucleic acids in fish liver and muscle tissue. Furthermore, the metabolites and compounds of cigarette butt juice were detectable in the liver and muscle tissue of fishes. In conclusion, this study showed that exposure to CBL can have adverse effects on fish health.

Concerns about global warming and greenhouse gases have increased the interest of governments and the public sector to find solutions. To reduce the effects of global warming caused by greenhouse gases, especially methane, it is necessary to change animal production systems and adopt new strategic approaches. The reduction of enteric methane in livestock is a long-standing problem regarding the energy efficiency of consumed feed. In this review, the sources of production, dissemination, and introduction of accepted scientific and practical solutions in order to reduce methane gas in breeding and production units of dairy cows have been investigated. To carry out this research, a thorough search was conducted in articles published in valid databases between 1967 and 2022. A total of 213 articles were reviewed, and after screening, 159 were included in the study and analyzed using a PRISMA flow diagram. In general, low livestock efficiency, low-quality feed, a shortage of knowledge, and inadequate investment are the main causes of emission of these gases in poor or developing countries. On the other hand, developing countries may not always have access to the same methods that are utilized in industrialized countries to minimize the production of methane and other greenhouse gases like nitrous oxide. According to their conditions, developing countries should use the available tools to reduce methane production and emission, considering the costs, local knowledge, feasibility, and local laws. In future, there will be a greater need for interdisciplinary research to look for sustainable and acceptable methods for reducing methane emissions and other greenhouse gases from animal husbandry units, especially dairy cows. To change the population of rumen methanogens, as the main producers of methane, strategies such as feeding management, addition of inhibitors and vaccination are suggested. Also, there is a need for more applied research for reducing methane emissions.

Contaminants such as nano-polystyrenes (NPs) and heavy metal cocktail (HMC) have been found to disrupt physiological functions in aquatic organisms. Although HMC and NPs alone induce oxidative stress, their combined effects are not well understood. This study aimed to assess the combined effects of HMC and NPs on the freshwater shrimp (Macrobrachium rosenbergii). Shrimp were divided into seven groups, including the control group, and the experimental groups co-exposed to 0, 50, 100, 150, 200, and 250 µg/L NPs combined with 0.5 mg/L HMC. After 14 days, shrimp were sampled, and their hepatopancreas and muscle tissues were analyzed for oxidative biomarkers, biochemical parameters, and metabolic profiles. Moreover, the bioaccumulation rate of heavy metals was measured. Results showed that co-exposure to NPs and HMC increased superoxide dismutase, glutathione peroxidase, glutathione reductase activities, and malondialdehyde levels, while reducing glutathione and total antioxidant capacity. The integrated biomarker response indicated that co-exposure to HMC and NPs induces oxidative stress. A significant decrease was observed in aspartate aminotransferase, gamma-glutamyl transpeptidase, and alkaline phosphatase activities, glycogen, triglyceride, and total protein levels. However, lactate dehydrogenase activity was significantly increased. Co-exposure to HMC and NPs increased heavy metal bioaccumulation, induced oxidative stress, biochemical changes, and enhanced HMC toxicity in shrimp.