Growth, hemato-biochemical, immune-antioxidant response, and gene expression in Nile tilapia (Oreochromis niloticus) received nano iron oxide-incorporated diets

Fe-NPs and Zn-NPs: Advancing Aquaculture Performance Through Nanotechnology

Aquaculture is a growing industry facing several challenges, including disease control, water quality management, and sustainable feed production. One potential solution to these challenges is the use of trace elements such as iron (Fe) and zinc (Zn), either in their conventional form or as nanoparticles (NPs). Aquatic animals need these micronutrients for normal growth, physiological processes, and overall health. In marine species, iron boosts development, immunity, and disease resistance. At the same time, zinc enhances metabolism, synthesizes essential enzymes, and produces hormones that play a part in defenses, growth, reproduction, and antioxidative activities. According to this review, species-specific requirements by different Fe and Zn compounds have all emphasized the impacts on animal growth and development, antioxidant capacity, reproductive efficiency, and immunological response. However, NPs of Fe and Zn have been found to have higher bioavailability and efficacy than conventional forms. This work examines the effects of applications of Fe and Fe nanoparticles (Fe-NPs) and Zn and Zn nanoparticles (Zn-NPs) in aquaculture. However, the source of Fe and Zn in aquaculture species and administration volume may significantly impact efficacy. Nanotechnology boosts the positive benefits of Fe and Zn by converting them to their nanoforms (Fe-NPs) and (Zn-NPs), which are better used by animals and have a broader intake range. As a result, Fe-NPs and Zn-NPs offer an effective method for using nutrients in aquaculture.

Silica nanoparticles alleviate the immunosuppression, oxidative stress, biochemical, behavioral, and histopathological alterations induced by Aeromonas veronii infection in African catfish (Clarias gariepinus)

In the aquaculture industry, silica nanoparticles (SiNPs) have great significance, mainly for confronting diseases. Therefore, the present study aims to assess the antibacterial efficiency of SiNPs as a versatile trial against Aeromonas veronii infection in African catfish (Clarias gariepinus). Further, we investigated the influence of SiNPs in palliating the immune-antioxidant stress biochemical, ethological, and histopathological alterations induced by A. veronii. The experiment was conducted for 10 days, and about 120 fish were distributed into four groups at random, with 30 fish each. The first group is a control that was neither exposed to infection nor SiNPs. The second group (SiNPs) was vulnerable to SiNPs at a concentration of 20 mg/L in water. The third group was experimentally infected with A. veronii at a concentration of 1.5 × 107 CFU/mL. The fourth group (A. veronii + SiNPs) was exposed to SiNPs and infected with A. veronii. Results outlined that A. veronii infection induced behavioral alterations and suppression of immune-antioxidant responses that appeared as a clear decline in protein profile indices, complement 3, lysozyme activity, glutathione peroxidase, and total antioxidant capacity. The kidney and liver function biomarkers (creatinine, urea, alkaline phosphatase, and alanine aminotransferase) and lipid peroxide (malondialdehyde) were substantially increased in the A. veronii group, with marked histopathological changes and immunohistochemical alterations in these tissues. Interestingly, the exposure to SiNPs resulted in a clear improvement in all measured biomarkers and a noticeable regeneration of the histopathological changes. Overall, it will establish that SiNPs are a new, successful tool for opposing immunological, antioxidant, physiological, and histopathological alterations induced by A. veronii infection.

Excessive dietary iron exposure increases the susceptibility of largemouth bass (Micropterus salmoides) to Aeromonas hydrophila by interfering with immune response, oxidative stress, and intestinal homeostasis

Iron is an essential cofactor in the fundamental metabolic pathways of organisms. Moderate iron intake can enhance animal growth performance, while iron overload increases the risk of pathogen infection. Although the impact of iron on the pathogen-host relationship has been confirmed in higher vertebrates, research in fish is extremely limited. The effects and mechanisms of different levels of iron exposure on the infection of Aeromonas hydrophila in largemouth bass (Micropterus salmoides) remain unclear. In this study, experimental diets were prepared by adding 0, 800, 1600, and 3200 mg/kg of FeSO4∙7H2O to the basal feed, and the impact of a 56-day feeding period on the mortality rate of largemouth bass infected with A. hydrophila was analyzed. Additionally, the relationships between mortality rate and tissue iron content, immune regulation, oxidative stress, iron homeostasis, gut microbiota, and tissue morphology were investigated. The results showed that the survival rate of largemouth bass infected with A. hydrophila decreased with increasing iron exposure levels. Excessive dietary iron intake significantly increased iron deposition in the tissues of largemouth bass, reduced the expression and activity of antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase, increased the content of lipid peroxidation product malondialdehyde, and thereby induced oxidative stress. Excessive iron supplementation could influence the immune response of largemouth bass by upregulating the expression of pro-inflammatory cytokines in the intestine and liver, while downregulating the expression of anti-inflammatory cytokines. Additionally, excessive iron intake could also affect iron metabolism by inducing the expression of hepcidin, disrupt intestinal homeostasis by interfering with the composition and function of the gut microbiota, and induce damage in the intestinal and hepatic tissues. These research findings provide a partial theoretical basis for deciphering the molecular mechanisms underlying the influence of excessive iron exposure on the susceptibility of largemouth bass to pathogenic bacteria.

Iron supplementation in the diets of hybrid catfish (Ictalurus punctatus × I. furcatus) juveniles affected haematocrit levels and potentially decreased disease resistance to Edwardsiella ictaluri

To prevent catfish idiopathic anaemia, diets fortified with iron have been adopted as a regular practice on commercial catfish farms to promote erythropoiesis. However, the effects of prolonged exposure of excess dietary iron on production performance and disease resistance for hybrid catfish (Ictalurus punctatus × I. furcatus) remains unknown. Four experimental diets were supplemented with ferrous monosulphate to provide 0, 500, 1000, and 1500 mg of iron per kg of diet. Groups of 16 hybrid catfish juveniles (~22.4 g) were stocked in each of 20, 110-L aquaria (n = 5), and experimental diets were offered to the fish to apparent satiation for 12 weeks. At the end of the study, production performance, survival, condition indices, as well as protein and iron retention were unaffected by the dietary treatments. Blood haematocrit and the iron concentration in the whole-body presented a linear increase with the increasing the dietary iron. The remaining fish from the feeding trial was challenged with Edwardsiella ictaluri. Mortality was mainly observed for the dietary groups treated with iron supplemented diets. The results for this study suggest that iron supplementation beyond the required levels does affect the blood production, and it may increase their susceptibility to E. ictaluri infection.

Evaluation of growth, nutrient absorption, body composition and blood indices under dietary exposure of iron oxide nanoparticles in Common carp (Cyprinus carpio)

The bioavailability, small size and direct absorption in the blood, make nanoparticles (NPs) a remarkable feed additive in the aquaculture industry. Therefore, dietary iron oxide nanoparticles (Fe2 O3 -NPs) were used to examine their effects on growth, nutrient absorption, body composition and blood indices in Cyprinus carpio (Common carp) fingerlings. Healthy C. carpio fingerlings (n = 270) were fed with six canola meal based experimental diets (D1-control, D2, D3, D4, D5, D6) supplemented with 0, 10, 20, 30, 40 and 50 mg/kg Fe2 O3 -NPs respectively. A total of 15 fingerlings (average initial weight 5.51 ± 0.04 g/fish) were kept in triplicates for 70 days. The results indicated that maximum growth performance, apparent digestibility coefficient, body composition and haematological parameters were observed in 40 mg/kg Fe2 O3 -NPs supplementation. All the experimental diets were significantly improved (p < 0.05) in all the above parameters than control diet. In the present research, the recommended dosage of Fe2 O3 -NPs as dietary supplement is 40 mg/kg for improving the growth, nutrient absorption, body composition and haematological indices in C. carpio fingerlings. Hence, this study demonstrates the potential of NPs to improve the health of fish.

Chlorella vulgaris extract conjugated magnetic iron nanoparticles in nile tilapia (Oreochromis niloticus): Growth promoting, immunostimulant and antioxidant role and combating against the synergistic infection with Ichthyophthirius multifiliis and Aeromonashydrophila

Nile tilapia reared under intensive conditions was more susceptible for Ichthyophthirius multifilii (I. multifiliis) infection eliciting higher mortality, lower productive rate and further bacterial coinfection with Aeromonas hydrophila (A. hydrophila). The higher potency of magnetic field of iron oxide nanoparticles (NPs) can kill pathogens through inhibiting their viability. Herein, coating of Chlorella vulgaris extract (ChVE) with magnetic iron oxide NPs (Mag iron NPs) can create an external magnetic field that facilitates their release inside the targeted tissues. Thus, the current study is focused on application of new functionalized properties of Mag iron NPs in combination with ChVE and their efficacy to alleviate I. multifiliis and subsequent infection with A. hydrophila in Nile tilapia. Four hundred fingerlings were divided into: control group (with no additives), three groups fed control diet supplemented with ChVE, Mag iron NPs and ChVE@Mag iron NPs for 90 days. At the end of feeding trial fish were challenged with I. multifiliis and at 9 days post challenge was coinfected by A. hydrophila. A remarkable higher growth rate and an improved feed conversion ratio were detected in group fed ChVE@Mag iron-NPs. The maximum expression of antioxidant enzymes in skin and gills tissues (GSH-Px, CAT, and SOD) which came in parallel with higher serum activities of these enzymes was identified in groups received ChVE@Mag iron-NPs. Furthermore, group fed a combination of ChVE and Mag iron-NPs showed a boosted immune response (higher lysozyme, IgM, ACH50, and MPO) prior to challenge with I. multifiliis. In contrast, fish fed ChVE@Mag iron-NPs supplemented diet had lower infection (decreased by 62%) and mortality rates (decreased by 84%), as well as less visible white spots (decreased by 92 % at 12 dpi) on the body surfaces and mucous score. Interestingly, post I. multifiliis the excessive inflammatory response in gill and skin tissues was subsided by feeding on ChVE@Mag iron-NPs as proved by down regulation of IL-1β, TNFα, COX-2 and iNOS and upregulation of IL-10, and IgM, IgT and Muc-2 genes. Notably, group exposed to I. multifiliis-showed higher mortality when exposed to Aeromonas hydrophilia (increased by 43 %) while group fed ChVE@Mag iron-NPs exhibited lower morality (2%). Moreover, the bacterial loads of A. hydrophilia in fish infected by I. multifiliis and fed control diet were higher than those received dietary supplement of ChVE, Mag iron-NPs and the most reduced load was obtained in group fed ChVE@Mag iron-NPs at 7 dpi. In conclusion, ChVE@Mag iron-NPs fed fish had stronger immune barrier and antioxidant functions of skin and gills, and better survival following I. multifiliis and A. hydrophilia infection.

Long-term exposure to small-sized silica nanoparticles (SiO2-NPs) induces oxidative stress and impairs reproductive performance in adult zebrafish (Danio rerio)

The widespread use of silica nanoparticles (SiO2-NPs) in various industries, including chemical polishing, cosmetics, varnishes, medical, and food products, has increased the risk of their release into aquatic ecosystems. The toxic effects of small-size SiO2-NPs on the reproductive performance of zebrafish (Danio rerio) have yet to be widely studied. This study aimed to investigate the impact of chronic exposure to small-sized (35 ± 6 nm) SiO2-NPs on adult zebrafish through waterborne exposure to concentrations of 5 (SNP5), 10 (SNP10), 15 (SNP15), and 20 (SNP20) μg/L of SiO2-NPs for 28 days. Our results showed that SiO2-NPs significantly impacted several biochemical parameters, including cholesterol, triglycerides, LDL, HDL, total protein, albumin, urea levels, and alkaline phosphatase and aspartate aminotransferase activity. Cortisol and glucose levels in the SNP20 group significantly differed from the control group. All the exposed groups, apart from SNP5, experienced a significant increase in their total immunoglobulin levels and lysozyme activity. While there was a considerable increase in the activity of catalase and superoxide dismutase in all exposed groups, the expression of antioxidant genes did not appear to be affected. Furthermore, the expression level of il8 was significantly higher in SNP5 and SNP10 than in other treatments. Exposure to SiO2-NPs caused a decrease in gonad weight, absolute fecundity, and larval survival rate, particularly in the SNP20 group. The present study indicates that SiO2-NPs can harm zebrafish and thus further research is necessary to assess their health and environmental risks.