Potential role of dietary chitosan nanoparticles against immunosuppression, inflammation, oxidative stress, and histopathological alterations induced by pendimethalin toxicity in Nile tilapia

Toxicological effects of chemical pesticides in fish: Focusing on intestinal injury and gut microbial dysbiosis

The gut is susceptible to environmental pollutants and is a crucial barrier to exchanging internal and exterior substances in animals and humans. Intestinal microbiota plays vital roles in nutrition metabolism, synthesis of functional compounds, immune regulation, inflammation, and infection. Gut microbiota dysbiosis can induce intestinal physical barrier damage, trigger inflammation, and increase gut permeability. Intestinal barrier dysfunction facilitates the entry of pathogenic bacteria and harmful chemicals into the body through the blood circulation system, potentially causing neurotoxicity, hepatotoxicity, respiratory toxicity, growth inhibition, and even death. Herein, we overviewed the knowledge on the toxic effects of chemical pesticides on fish intestines and gut microbiota in the latest decade (2015-2025) and attempted to summarize the potential toxicological mechanisms. Chemical pesticide exposure can cause intestinal damage, impair immune function, and disrupt gut microbiota in fish. Gut microbial dysbiosis was strongly associated with intestinal injury. Alterations in gut microbiome metabolites, such as lipopolysaccharide, peptidoglycan, and short-chain fatty acids, have been linked to intestinal damage, inflammation, and changes in permeability. The mechanisms underlying intestinal injury in fish exposed to chemical pesticides included apoptosis, oxidative stress, and inflammation, which are mediated by reactive oxygen species pathways as well as death receptor and mitochondrial signaling pathways. Furthermore, pesticide-induced intestinal dysbiosis can cause neurotoxicity and hepatotoxicity through the microbiome-gut-brain/liver axis.

Azolla pinnata mitigates pendimethalin induced immunotoxicity, oxidative stress and histopathological changes in Oreochromis niloticus

Aquatic animals face multiple threats, including pesticides, heavy metals, and other environmental pollutants, risking their health and survival. Limited bioremediation studies have been conducted on the detrimental impacts of herbicides on fish. This study focused on the impact of the herbicide pendimethalin (PD) on Oreochromis niloticus and assessed the protective role of Azolla pinnata (AZ), an aquatic fern known for its phytoremediation and antioxidant properties. O. niloticus (n = 270, 34.17 ± 2.41 g) were divided into six groups in triplicate: the control (CTR), AZ-supplemented (125 g/kg diet), PD-exposed (0.5 and 1 mg PD/L), and PD-exposed with AZ supplementation (0.5 and 1 mg PD/L + AZ) groups for 28 days. PD exposure caused substantial reductions in growth performance and hematological indices (hemoglobin concentration (Hb) and red blood cell (RBC) count), with significant increases in white blood cell (WBC) count. Oxidative damage from PD exposure was evidenced by decreased superoxide dismutase (SOD) activity and acetylcholinesterase (AChE) levels, along with increased malondialdehyde (MDA) levels in hepatic and gill tissues. PD-exposed fish also presented reduced phagocytic activity (PA) and index (PI), along with decreased lysozyme activity and resistance to Pseudomonas aeruginosa infection. Additionally, hepatic and renal damage markers (AST, ALT, ALP, urea, and creatinine) and stress indicators (cortisol and glucose) were notably elevated. Severe tissue and cellular damage further highlight PD-induced damage. AZ supplementation had a protective effect, almost restoring normal growth performance, hematological parameters, and antioxidant defenses. AZ improved SOD and AChE activity and reduced MDA levels, mitigating oxidative damage. AZ also improved immune responses, restoring PA, PI, and lysozyme activity and bacterial resistance. Furthermore, AZ alleviated hepatic and renal damage, normalized stress markers, and mitigated tissue and morphological abnormalities, preserving tissue integrity. This study underscores the potential of dietary AZ supplementation (12.5%) as a growth promoter, antioxidant, and immunostimulant in aquaculture, effectively enhancing resistance to environmental toxicants and bacterial infections.

Mitigation of cadmium toxicity in African catfish using biological Nano chitosan: insights into biochemical, genotoxic, and histopathological effects

BACKGROUND

Cadmium is a highly toxicant heavy metal that poses serious risks to aquatic organisms, animals, and humans. Recent studies have investigated using biological chitosan nanoparticles (Bio-CHNPs) as a potential solution to alleviate the harmful effects of Cd exposure, particularly in aquaculture. Bio-CHNPs have gained attention for their applications in drug delivery and biomedical research, indicating their potential utility in addressing environmental toxicity.

OBJECTIVE

This research aims to explore the effectiveness of Bio-CHNPs in mitigating cadmium chloride (CdCL2) toxicity in African catfish (Clarias gariepinus).

METHODS

One hundred and twenty (n = 120) catfish were divided into 4 groups; G1 (control); G2, intoxicated with 10% LC50 of CdCL2; G3 received 3 g/kg of Bio-CNPs; G4, treated with 10% LC50 of CdCL2 and Bio-CNPs 3 g/kg feed.

RESULTS

CdCl2 exposure resulted in severe liver, intestine, and kidney damage, which was evidenced by alterations in biochemical parameters, hormonal imbalance, DNA damage, and micronucleus formation. Antioxidant defense mechanisms were compromised, as the activities of Superoxide Dismutase (SOD), Total Antioxidant Capacity (TAC), and Catalase (CAT) were reduced. mRNA expression levels of inflammatory cytokines such as IL-1β, IL-8, and LBP were also significantly elevated following CdCl2 exposure. Conversely, Bio-CHNPs treatment showed antioxidant and anti-inflammatory effects, greatly lowering the biochemical, genotoxic, and histopathological effects induced by CdCl2.

CONCLUSION

The outcomes of this study are indicative of the potential of Bio-CHNPs as a promising aquaculture feed supplement, with a dual advantage of antagonizing the toxicity of environmental pollutants like Cd and imparting antioxidant and immunomodulatory effects. Bio-CHNP supplementation can be a viable strategy for remedying aquatic environmental heavy metal pollution, with the ultimate safeguarding of human health and ecosystem balance.

The potential effects of corn cob biochar on mitigating pendimethalin-induced toxicity in Nile tilapia (Oreochromis niloticus): Effects on hematological, biochemical, antioxidant-immune parameters, and histopathological alterations

This study aims to examine the restorative impact of corn cob biochar (CCB) on pendimethalin (PMD)-induced toxicity in Oreochromis niloticus. Fish were divided into four groups: the first control group without treatment, the second group (CCB) exposed to 10 g CCB/L, the third group (PDM) exposed to 0.355 mg PDM/L, and the fourth group (PDM+ CCB) receiving both 0.355 mg PDM/L and 10 g CCB/L for 30 days. PDM exposure resulted in behavioral alterations, low survival rate (73.33 %), hematological and biochemical impairments, increased oxidative stress, suppressed immunity, and histopathological damage in gill, liver, and brain tissues. Co-treatment with CCB significantly alleviated these effects, as evidenced by improved survival rate (88.88 %), hematological, biochemical, and antioxidant-immune parameters and reduced histopathological alterations. In conclusion, CCB demonstrated a promising potential to mitigate PDM-induced toxicity in O. niloticus by enhancing physiological, biochemical, and histological resilience.

Impact of sub-lethal Aclonifen intoxication on biochemical and stress markers on Oncorhynchus mykiss: an integrative assessment of multi-biomarker responses

Aclonifen is a diphenyl ether herbicide being included in the list of priority substances. Nevertheless, the data related to its sublethal effects on fish are limited. Therefore, the present study has been carried out to investigate the toxic effects of aclonifen in juvenile Oncorhynchus mykiss following 24, 48, 72 and 96 hours of application to sublethal concentrations of 12.7, 63.5 and 127 μg/L. The application resulted in altered blood biochemistry appearing as hyperglycemia, decreased cholesterol and induced activities of transaminases of ALT and AST. The inhibition of AChE in brain, gill and liver was unimportant revealing its weak potential as anticholinesterase. The induction recorded for SOD, CAT, GPx and GST activities was accompanied with sustained elevation in TBARS and PC levels. It demonstrates both the pro-oxidant potential of aclonifen and oxidation of lipid and proteins resulting in the loss of membrane integrity and protein function. Hyperglycemic condition and decreased protein levels in gill and liver might be proposed as general adaptive responses to compensate increased energy demand. The integrative assessment of multi-biomarker responses shows concentration and duration related rise in calculated indexes. CAT, PC and SOD achieved the maximum scores for brain, gill and liver, respectively. Considering the results, oxidative stress inducing potential and weak anticholinesterase activity along with its disturbing impact on blood biochemistry were evidenced. Moreover, adverse affects observed after short term application on O. mykiss, present the potential risk aclonifen may cause at population level in aquatic ecosystems emphasizing the importance of pesticide regulations to avoid adverse impacts on non-target species.

The combined effect of herbicide and Bacillus thuringiensis exposure delays development in the red flour beetle

The use of herbicides and their long persistence in the environment have raised concerns about potential harm to ecosystems and human health. However, there is a gap in the knowledge regarding the effects of continuous exposure to residues or admitted field doses on non-target organisms such as insects that inhabit croplands and play key ecological roles. Furthermore, the potential impact of this exposure on host-pathogen interactions remains largely unstudied. This study adopted an eco-immunological perspective, investigating the influence of herbicides on an organism's interaction with natural pathogens. The impact of this combination of multiple stressors was studied in larvae of the red flour beetle, Tribolium castaneum Herbst, 1797, previously treated with a pendimethalin-based commercial formulation (PND) and exposed to the natural entomopathogen Bacillus thuringiensis (1x109, 1x1010 cells/mL). The effects of three PND concentrations (i.e. a recommended field rate, a soil contaminant concentration and the maximum residue limit admitted in grain in EU countries: 4L/ha, 13 and 0.05 ppm, respectively) on life history traits such as developmental time, pupation rate and survival rate and the expression levels of antimicrobial peptides (AMPs) were assessed. The results showed that even at doses considered safe for human consumption or field application, exposure to PND had an impact on beetle larvae, affecting their vulnerability to B. thuringiensis. The combined experience of exposure to PND and B. thuringiensis at the larval stage resulted in a delay of larval development, a reduction in the number of pupae and emerging adults, and alterations in their body condition. Moreover, changes in the expression levels of the analysed AMPs, including Attacin 1, Defensin 2 and Coleoptericin 2, were recorded as markers for immune activity against the bacterium. The findings of this study highlight the general need for further studies on the effects of commonly used herbicides on the physiology of non-target organisms and on host-pathogen interactions at the community level. Additionally, there is a need for the establishment of revised residual levels that are deemed non-toxic to soil organisms and humans.

Dietary Pediastrum boryanum microalgal extract improves growth, enhances immunity, and regulates immune-related genes in Nile tilapia

BACKGROUND

Identifying alternative sustainable feed sources with high nutritional values is crucial for the future of environmentally and socially responsible aquaculture. In this regard, microalgae have been proven to have positive effects on fish health, which overwhelmed our interest in this study.

METHODS

Pediastrum boryanum (P. boryanum) was incorporated into Nile tilapia feed at concentrations of 0, 0.75, and 1.5 mg/kg, as control, PbExt0.75, and PbExt1.5 groups to assess its effects on growth and biochemical indices, oxidant/antioxidant activities, immune and stress-related gene expression, and intestinal morphology.

RESULTS

After 8 weeks, fish fed P. boryanum supplemented feed exhibited significant increases in final weight, length, condition factor, body weight gain, and specific growth rate, while the spleen-somatic index (SSI) and hepatosomatic index (HSI) showed no significant differences compared to the control group. Dietary P. boryanum supplementation also enhanced IgM levels and lysozyme activity, along with no marked effect on markers of liver function enzymes (alanine aminotransferase/ALT and aspartate aminotransferase/AST) or protein status (total protein and albumin). Furthermore, P. boryanum addition increased the activity of superoxide dismutase (SOD), catalase (CAT), and reduced glutathione (GSH) enzymes, highlighting its antioxidant potential, whereas malondialdehyde (MDA) concentrations showed no significant differences among the groups. Gene expression analysis revealed that tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10), and transforming growth factor-β1 (TGF-β1) expression notably increased in groups fed P. boryanum containing feed, while no significant difference was observed in hepatic Heat Shock Protein 70 (HSP70) mRNA expression. Histopathological examination revealed no adverse effects of P. boryanum supplementation on the liver, spleen, or intestinal tissues. Villous height and villous surface area were notably increased in the high P. boryanum supplementation group, suggesting improved intestinal integrity and nutrient absorption.

CONCLUSION

Dietary P. boryanum supplementation can potentially improve growth performance, immune response, antioxidant status, and intestinal health of Nile tilapia, making it a promising candidate for sustainable aquaculture.

The effects of dietary Spirulina platensis or curcumin nanoparticles on performance, body chemical composition, blood biochemical, digestive enzyme, antioxidant and immune activities of Oreochromis niloticus fingerlings

CONTEXT

Recently, prioritize has been given to using natural phytogenic or nano compounds as growth promoters and immunostimulants in fish diets as an alternative to antibiotics.

AIMS

The main propose of this trial was to determine the impact of supplementing diets with spirulina or curcumin nanoparticles on the performance and health indicators of Nile tilapia fingerlings.

METHODS

In a 56-day feeding trial, 180 tilapia fingerlings were assigned into three main groups, as follows: 1st, control group, 2nd, Spirulina platensis (SP; 5 g kg-1 diet) and 3rd, curcumin nanoparticles (CUR-NPs; 30 mg kg-1 diet).

KEY RESULTS

Incorporating tilapia diets with SP or CUR-NPs significantly improved performance, body chemical analysis, blood biochemical and hematological indices, digestive enzyme activities, and antioxidant and immunostimulant features compared to the control.

CONCLUSION

Fortified tilapia diets with CUR-NPs or SP efficiently boost the productivity and health of Nile tilapia fingerlings.

IMPLICATIONS

The research introduces new practical solutions for applying safe feed additives as alternatives to antibiotics in tilapia farming.

Neurotoxicity of singular and combined exposure of Oreochromis niloticus to methomyl and copper sulphate at environmentally relevant levels: Assessment of neurotransmitters, neural stress, oxidative injury and histopathological changes

Aquatic organisms are concomitantly exposed to multiple noxious chemicals that can be discharged into water bodies. We aimed to investigate the single and simultaneous sub-acute exposure to copper and methomyl on juvenile Oreochromis niloticus. Compared to the controls, the outcomes revealed that brain of methomyl-exposed fish displayed significant declines in the activities of SOD, CAT, and GST in addition to higher MDA and lower GSH levels. Methomyl induced notable declines in levels of GABA and acetylcholine esterase in brain and muscle of exposed fish. Noteworthy downregulated gene expression levels of TNF-α, HSP-70 together with upregulated c-fos were evident in brain of fish expose to either of tested compounds. Marked apoptotic changes were observed in fish brain exposed to copper and methomyl indicated by augmented immune expression of caspase-3. Conclusively, the results indicated the possible interaction between both compounds with subsequent toxic effects that differ from their single exposure.

Elimination of Pendimethalin in Integrated Rice and Procambarus clarkii Breeding Models and Dietary Risk Assessments

This study investigated elimination of the herbicide pendimethalin using an integrated rice and Procambarus clarkii breeding model of indoor and outdoor (pond culture) exposure tests. The pendimethalin levels in 484 samples from the primary rice and P. clarkii integrated breeding areas in Hubei province were monitored, and dietary risk assessments of pendimethalin were calculated. Pendimethalin was quantified using high-performance liquid chromatography tandem mass spectrometry, and detection levels were linear in the range of 1.0 to 10.0 μg/L, and peak areas were positively correlated with concentration, with a correlation coefficient of 0.9996. Recoveries ranged from 86.9 to 103.5%, and the limit of quantitation was 2.5 × 10⁻⁴ μg/L in water, and 1 × 10⁻² μg/kg in tissues, sediments, and waterweeds. The dissipation rate of pendimethalin in tissues and water followed first-order kinetics, with half-lives of 0.51–5.64 d. In 484 samples taken from aquaculture farms, pendimethalin was detected in 8.67% of the samples at levels in the range of 1.95 to 8.26 μg/kg in Hubei province from 2018 to 2020. The maximum residue limit of pendimethalin in P. clarkii has not been established in China, but our dietary risk assessments indicated that consumption of P. clarkii from integrated rice farms was acceptable.