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This study focuses on the comparative metabolic profiling and effects of two steroid types: natural and synthetic, specifically 17α-methyl testosterone (17α-MT) at varying concentrations (1.5, 2, and 3 mg/kg) in rainbow trout (Oncorhynchus mykiss). Over a 75-day feeding trial, growth metrics, such as feed efficiency, daily specific growth, live weight gain, total weight gain, and survival rate were systematically monitored every 15 days. At the end of the feeding trial, histopathology, immunohistochemistry, and metabolome analyses were performed in the high-concentration groups (3 mg/kg natural and 3 mg/kg synthetic), in which the lowest survival rate was determined. Key findings reveal that the type of hormone significantly influences growth parameters. While some natural steroids enhanced certain growth aspects, synthetic variants often yielded better results. The metabolomic analysis highlighted significant shifts in the metabolism of tryptophan, purine, folate, primary bile acids, phosphonates, phosphinates, and xenobiotics via cytochrome P450 pathways. Histopathologically, the natural hormone groups showed similar testicular, hepatic, muscular, gill, cerebral, renal, and intestinal tissue structures to the control, with minor DNA damage and apoptosis observed through immunohistochemistry. Conversely, the synthetic hormone groups exhibited moderate DNA damage and mild degenerative and necrotic changes in histopathology. [ABSTRACT FROM AUTHOR]

Microplastic (MP) pollution has become a health concern subject in recent years. Althoughann increasing number of studies about the ingestion of microplastics by fish, research on the oxidative stress response to MPs in natural environments is quite limited. In this study, the identification and characterization of MPs in gill (G), muscle tissues (M), and gastrointestinal tract (GI) of turbot (Scophthalmus maximus) were evaluated. Oxidative damage of MPs on the brain (B), liver (L), gill (G), and muscle (M) tissues as well as their effect on superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), paraoxonase (PON), arylesterase (AR) myeloperoxidase (MPO), and malondialdehyde (MDA) biomarkers were evaluated. The potential transmission of MPs from muscle tissues to humans was examined. Results showed that gills contain the highest amounts of MPs, ethylene propylene is the most dominant polymer type, black and blue are the most common MP color, fiber is the most common shape, and 50-200 µm is the most common MP size. Results showed that MPs cause oxidative stress of tissues with inhibiting effect on enzyme activities and promoting impact on lipid peroxidation. The oxidative damage mostly affected the liver (detoxification organ) followed by gill tissue. The intake of MPS in the European Union was estimated by EFSA as 119 items/year, while in Turkey it is 47.88 items/year. This study shows that more research is needed in terms of ecosystem health and food chain safety. The risk assessment of MPs in living organisms and environmental matrices including food safety and human health should be considered a public health issue. [ABSTRACT FROM AUTHOR]

Nowadays, the unique features of nanoparticles (NPs) have encouraged new applications in different areas including biology, medicine, agriculture, and electronics. Their quick joining into daily life not only enhances the uses of NPs in a wide range of modern technologies but also their release into the aquatic environment causes inevitable environmental concerns. On the other hand boron exhibits key physiological effects on biological systems. This research was designed for evaluating the toxicity of magnetite nanoparticles (Fe3O4-MNPs) on aquatic organisms and obtaining data for the information gap in this area. In this study, Rainbow trout (Oncorhynchus mykiss) was considered as an aquatic indicator, and trials were designed as Ulexite (a boron mineral, UX) treatment against exposure to Fe3O4-MNPs. Synthesized and characterized Fe3O4-MNPs were exposed to rainbow trouts in wide spectrum concentrations (0.005–0.08 mL/L) to analyze its lethal dose (LC50) and cytoprotective properties by UX treatment were assessed against Fe3O4-MNPs applications for 96 h. For the initial toxicity analysis, hematological parameters (blood cell counts) were examined in experimental groups and micronucleus (MN) assay was performed to monitor nuclear abnormalities after exposure to NPs. Biochemical analyzes in both blood and liver samples were utilized to assess antioxidant/oxidative stress and inflammatory parameters. Also, 8-hydroxy-2'-deoxyguanosine (8-OHdG) assay was used to investigate oxidative DNA lesions and Caspase-3 analysis was performed on both blood and liver tissues to monitor apoptotic cell death occurrence. When antioxidant enzymes in blood and liver tissue were examined, time-dependent decreases in activity were determined in SOD, CAT, GPx, and GSH enzymes, while increased levels of MDA and MPO parameters were observed in respect to Fe3O4-MNPs exposure. It was found that TNF-α, Il-6 levels were enhanced against Fe3O4-MNPs treatment, but Nrf-2 levels were decreased at the 46th and 96th h. In the 96th application results, all parameters were statistically significant (p < 0.05) in blood and liver tissue, except for the IL-6 results. It was determined that the frequency of MN, the level of 8-OHdG and caspase-3 activity increased in respect to Fe3O4-MNPs exposure over time. Treatment with UX alleviated Fe3O4-MNPs-induced hematotoxic and hepatotoxic alterations as well as oxidative and genetic damages. Our findings offer strong evidence for the use of UX as promising, safe and natural protective agents against environmental toxicity of magnetite nanoparticles. [ABSTRACT FROM AUTHOR]

Acetyl ferrocene (AFC) is being used commonly in several industrial applications and scientific diciplines. Hence, in this study we aimed to determine the LC50 value of AFC, and evaluate the toxicity potential by AFC exposure on rainbow trout (Oncorhynchus mykiss) for 96 h. We also focused to investigate whether UX conferred a protection against AFC-induced toxic insults in fish. For this purpose, some stress related endpoints were measured in blood and liver tissues in a multibiomarker approach. The exposure to AFC observed inhibition/induction of hematological parameters by AFC was slowed down after co-application with UX and AFC. However, UX was found to be ineffective for minimising AFC-induced micronucleus formation after 96 h. Moreover, it was determined that supplementation with UX exhibited activity in favour of antioxidants and inhibited MDA / MPO levels. Again, time-dependent inhibition of Nrf-2 levels, stimulation of IL-6 and TNF-α levels by AFC were ameliorated after co-application with UX. Ultimately, administration with UX suppressed the accumulation of 8-OHdG adducts and caspase-3 levels as compared to only AFC treatment. In a conclusion UX exerted significant protection potency against AFC-induced hematotoxic, oxidative, genotoxic and cytotoxic damages, hence could be a new source of natural protective agents in environment. [ABSTRACT FROM AUTHOR]

BACKGROUND: Temperature, which affects numerous physiological processes, has been described as the 'main ecological factor' for fish. The aim of this modeling study is to explore the impact of climate‐induced temperature changes on fish fillet quality and shelf life. RESULTS: Temperature stress in rainbow trout affected ash and moisture, and inhibited myofibril fragmentation in the fillets. However, with the increase in temperature, there was a decrease in the total amount of saturated fatty acids (∑SFA) and there were significant increases in the total amount of omega 3 (∑n3) and 22:6n‐3 (DHA). It was determined that temperature increase had a negative effect on color, texture, water‐holding capacity, water activity, pH, lactic acid, and glycogen levels in fillets, and it had a positive effect by delaying microbial spoilage, especially in cold storage. CONCLUSION: This study suggest that the effects of climate change on product quality and shelf life in fish requires further research. It highlights knowledge gaps to guide future research in this emerging field. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Described as the 'main ecological factor', temperature, strongly affects the physiological stress responses of fish. In order to evaluate the effects of temperature variations on fish culture and food value chain, the present study was designed as a climate change model. Furthermore, the present study provides a theoretical basis for a better understanding of the mechanisms of the environmentally induced changes. In this direction, we examined the blood physiology and oxidative stress responses induced by temperature variation in the rainbow trout, a temperature-sensitive cold-water fish. The obtained results showed that climate changes promoted the inhibited activities' expressions and the development of potential tissue and hematological defense mechanisms against temperature-induced toxic damage. This study showed that climate change could be a subset of the studies on the stress physiology in aquaculture, which can be developed for new experimental designs and research collaborations. Furthermore, it highlights knowledge gaps to guide future research in this emerging field. [ABSTRACT FROM AUTHOR]

Although the number of studies documenting the presence of Microplastics (MP) in fish is increasing, research studies focused on its detoxification are very limited. In this study, rainbow trout (Oncorhyncus mykiss) were randomly divided into two groups after being fed with MPs (15% polypropylene [PP] +15% polyethylene [PE]) for 2 months. MP excretion without any application (PP+PE) in group I fish, and excretion of MPs with hydrogen-rich water (HRW) application (PP+PE+HRW) in group 2 were investigated under semi-static conditions for 21 days. This effect was also compared by using positive and negative control groups (Control [no treatment, free PP, PE or/and HRW] and only HRW group). In this direction, the following were determined: PP+PE chronic toxicity in aquatic organisms, the toxicity mechanism and the effect of HRW as a possible treatment method in blood tissue; with hematological indices ([RBC count [RBC], leukocyte count [WBC], hemoglobin value [Hb], hematocrit ratio [Hct], platelet count [PLT], hemoglobin count per erythrocyte [MCHC], mean hemoglobin amount per erythrocyte [MCH] and mean erythrocyte volume [MCV]) in other tissues (liver, gill and brain tissue) oxidative stress response (catalase [CAT]), glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD), glutathione (GSH), reactive oxygen products (ROS), malondialdehyde ([MDA] levels), DNA damage (8-OHdG: 8-Hydroxy-2-Deoxyguanosine), and the apoptosis (caspase 3) levels were investigated. In addition, acetylcholinesterase enzyme (AChE) activity, which is important in neurotoxicity pathways in the brain, was determined. The presence of plastics (PP/PE) in target tissues (muscle, liver, gill and gastrointestinal tract) was also obtained. The results showed that PP+PE caused toxicity in all three tissues. MPs showed an inhibiting effect on antioxidant enzyme activities and an inductive effect on MDA, ROS, 8-OHdG, and caspase 3 levels. HRW showed a mitigating effect on MP-mediated toxicity in O. mykiss brain, blood, gill, and liver by controlling the ROS/GSH/MDA pathway. HRW can be suggested as a costeffective and eco-friendly curative for the protection of fish from the oxidative damages produced by the ingestion of microplastics. [ABSTRACT FROM AUTHOR]