Beyond the surface: Consequences of methyl tert-butyl ether (MTBE) exposure on oxidative stress, haematology, genotoxicity, and histopathology in rainbow trout.

Concerns have been raised about the possible environmental effects of methyl tert-butyl ether (MTBE), which is widely used as a gasoline additive. This research aimed to look at the consequences of MTBE contamination on rainbow trout (Oncorhynchus mykiss), emphasizing oxidative stress, genotoxicity, and histopathological damage. After determining the LC50-96 h value, the effects of sub-lethal doses of MTBE (0 (control), 90, 180, and 450 ppm) on rainbow trout were investigated. In fish tissues, the levels of oxidative stress indicators such as malondialdehyde (MDA) and superoxide dismutase (SOD) were measured. The comet assay, which measures DNA damage in erythrocytes, was used to determine genotoxicity. Histopathological examinations were done on liver and gill tissues to examine potential structural anomalies. The results of this study show that MTBE exposure caused considerable alterations in rainbow trout. Increased oxidative stress was demonstrated by elevated MDA levels and decreased SOD activity, while the comet assay revealed dose-dependent DNA damage, implying genotoxic effects. Histopathological study revealed liver and gill tissue abnormalities, including cell degeneration, necrosis, and inflammation. Overall, this research highlights the possible sub-lethal effects of MTBE contamination on rainbow trout, stressing the need of resolving this issue. Future research should look at the impacts of chronic MTBE exposure and the possibility of bioaccumulation in fish populations.

Anodonta cygnea, a freshwater swan mussel, exposed to diazinon: toxicity thresholds in behaviour and physiology.

Swan mussels (Anodonta cygnea) have been suggested as suitable bioindicators for the presence of pollutants in the environment. Application of the physiological and behavioral markers in these sessile species can be beneficial for environmental monitoring. The present study aimed to investigate the relationship between the behavioral disorders of movement and siphoning associated with the inhibition of tissue Acetylcholinesterase (AChE). For experiments, overally 120 bivalves of Anodonta cygnea (mean total length 80.33 ± 6.7 mm) were transported from the agricultural drains and canals in Sari county (Mazandaran Province, Iran) to our laboratory. First, the LC50-96 h of diazinon was estimated according to the Organization for Economic Co-operation and Development (OECD 1992) guideline with static water conditions. The sub-lethal toxicity pesticide experiments were conducted on the basis of the lowest observed effect concentration (LOEC) and the maximum acceptable toxicant concentration (MATC). The LC50-96 h, LOEC, and MATC values of diazinon were 85.2, 42.1, and 8.5 mg L- 1, respectively. Based on the observations of mussels' movement, the burrowing and displacement decreased with the concentration of toxicant in water. Moreover, the presence of diazinon in water and its exposure to experimental animals significantly reduces their siphoning rate. The RDA showed that the AChE activity had a higher correlation with the siphoning behavior than the movement behavior. The comparison of enzyme activity at different exposure and recovery times showed that there was a significant difference among the groups affected by the consumed pesticide (p = 0.001, between contrasts). The most remarkable morphometric characteristic was the siphon opening that was inversely correlated with the enzymatic activity. Studies in bioethics might benefit from paying attention to these traits that are directly related to the level of toxicity and behavioral adaptations required for animal survival.

Cutaneous mucosal immune-parameters and intestinal immune-relevant genes expression in streptococcal-infected rainbow trout (Oncorhynchus mykiss): A comparative study with the administration of florfenicol and olive leaf extract.

This study evaluated changes in cutaneous mucosal immunity (total protein (TP) and immunoglobulin (TIg), lysozyme, protease, esterase, and alkaline phosphatase (ALP)) and some immune-related genes expression (tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), interleukin-8, hepcidin-like antimicrobial peptides (HAMP), and immunoglobulin M (IgM)) in the intestine of rainbow trout (Oncorhynchus mykiss) orally-administrated florfenicol (FFC) and/or olive leaf extract (OLE), experimentally infected with Streptococcus iniae. The juvenile fish (55 ± 7.6 g) were divided into different groups according to the use of added OLE (80 g kg-1 food), the presence/absence of FFC (15 mg kg-1 body weight for 10 consecutive days), and the streptococcal infectivity (2.87 × 107 CFU mL-1 as 30% of LD50-96h). The extract's chemical composition was analyzed using the high-performance liquid chromatography (HPLC) system. The skin mucus and intestine of fish were sampled after a 10-day therapeutic period for all groups, and their noted indices were measured. Our results signified that the oleuropein, quercetin, and trans-ferulic acid were the most obvious active components of OLE which were found by HPLC analysis. The combined use of OLE and FFC could lowered some skin mucus immunological indices (e.g., TP, TIg, and ALP), and the gene expression of inflammatory cytokines (e.g., TNF-α and IL-1ß) of rainbow trout. Moreover, lysozyme and protease activities respectively were invigorated by the FFC and OLE treatment. Also, the use of OLE as a potential medicine induced the gene expression of HAMP. As the prevention approach, it would be recommended to find the best dose of OLE alone or in combination with the drug through therapeutics period before the farm involved in the streptococcal infection.

A bioassay on tissue cholinesterase activity of Rutilus kutum (Kamensky, 1901) exposed to some common pesticides in Iran.

The toxicological effects of three commonly used pesticides in Iran on the fries of Caspian kutum (Rutilus kutum, Kamensky, 1901) were investigated through determining 50.00% lethal concentration (LC50) 96hr and cholinesterase (ChE) inhibition. The LC50 96-hr of carbaryl, glyphosate, and malathion were equal to 11.69, 6.64, and 0.97 mg L-1, respectively, that were considered as harmful (10.00 - 100 mg L-1), toxic (1.00 - 10.00 mg L-1) and very toxic (< 1.00 mg L-1) compounds for this species. The exposure of fries to sub-lethal concentrations of the pesticides over 15 days indicated that the average of ChE activity in the head and trunk were 1086.89 ± 124.34 and 627.36 ± 99.60 mU min-1 per mg protein, respectively, with a significant difference relative to each other. There was a significant difference between fry exposed to all three pesticides and the control group in cholinesterase inhibition. The fries exposed to carbaryl (890.12 ± 28.08 mU min-1 per mg protein) and glyphosate (891.77 ± 31.61 mU min-1 per mg protein) showed lower ChE inhibition than those exposed to malathion (790.00 ± 58.14 mU min-1 per mg protein).

DNA damage, acetylcholinesterase activity, and hematological responses in rainbow trout exposed to the organophosphate malathion.

Effects of sub-lethal concentrations (0 (control), 0.009, 0.014, and 0.023 ppm) of the organophosphate insecticide "malathion" to rainbow trout (Oncorhynchus mykiss) after the determination of LC50-96 h value (0.093 ppm) were evaluated. Changes in biomarkers of neurotoxicity (acetylcholinesterase (AChE) activity), genotoxicity (DNA damage), and hematological parameters (red (RBC) and white (WBC) blood cell count, hemoglobin (Hb), hematocrit (Hct), mean cell hemoglobin (MCH), mean cell volume (MCV), and mean cell hemoglobin concentration (MCHC)) were assessed for a 15-day exposure. A significant time- and dose-dependent reduction in AChE activities of gill, muscle, brain, and liver tissues was found. However, the AChE activity was less affected by malathion concentration than by exposure time. DNA damage of erythrocytes at different malathion concentrations increased by increasing the experimental time up to the fourth day. A decrease in the count of WBC, RBC, and Hct and an increase in the number of MCH and MCV were observed by increasing malathion exposure dose and time (p < 0.05). An increase in the malathion concentration and exposure time significantly resulted in a decrease in Hb and an increase in MCHC. A significant improvement in AChE activity; DNA damage; and RBC, Hb, Hct, MCV, and MCH indices was detected during a 30-day recovery period, but the WBC count changed insignificantly. The recovery pattern based on 100% water exchange with clean water could be a successful strategy to improve the biomarker responses of rainbow trout habituating in contaminated aquatic environments.

The in vitro and in vivo effect of tannic acid on Ichthyophthirius multifiliis in zebrafish (Danio rerio) to treat ichthyophthiriasis.

The in vitro antiparasitic effect of polyphenol tannic acid (TA) on Ichthyophthirius multifiliis theronts and tomonts was evaluated. In vitro antiparasitic assays revealed that TA in a dose- and time-dependent pattern through the damage of parasite plasma membrane could be 100% effective against I. multifiliis theronts at concentrations of 8 and 11 ppm during all the exposure times (45-270 min). The tomonts proliferation was completely inhibited by penetrating TA (at least 15 ppm for 22-hr exposure) into encysted tomont across the cyst wall. However, 10 ppm TA could result in a ninefold decrease in the population of live tomonts compared to the control group (p < 0.05). Although at theront concentrations of over 6,000 per zebrafish (Danio rerio), a 100% prevalence of ichthyophthiriasis during a 5-day exposure was recorded, results of in vivo tests showed that the parasite that pretreated up to 10 ppm TA for 70 min had not any capability to infect the studied zebrafish population. The acute toxicity (96 hr-LC50 ) of TA for zebrafish was 19.51 ppm. Thus, TA can be considered as a natural therapeutant to safely and efficiently improve the health of aquatic systems by controlling ichthyophthiriasis.