Abstract
Simple SummaryWaterborne exposure of Nile tilapia (Oreochromis niloticus) juveniles to sub-lethal concentrations of silicon dioxide nanoparticles (SiO2NPs) induced hepato-renal damage through elevation of aspartate transaminase (AST), alanine transaminase (ALT), and alkaline phosphatase (ALP) activities as well as creatinine and blood urea levels. SiO2NPs induced irreversible dose-dependent histopathological changes in the hepatopancreas, gills, and posterior kidneys, alongside modulation of the pro-inflammatory cytokines, apoptosis-related genes, and oxidative stress genes in gills and liver of exposed fish.The current investigation assessed the impacts of sub-lethal concentrations of silicon dioxide nanoparticles (SiO2NPs) on hepato-renal functions, histopathological characteristics, and gene transcription in gills and liver of Nile tilapia juveniles. Fish were exposed to 20, 40, and 100 mg/L of SiO2NPs for 3 weeks. Pairwise comparisons with the control group showed a significant dose-dependent elevation in serum ALP, ALT, and AST enzyme activities as well as blood urea and creatinine levels in SiO2NP-intoxicated groups. Exposure to 100 mg/L SiO2NPs significantly upregulated expression of HSP70, TNF-α, IL-1β, and IL-8 genes in the gills as compared to the control group. Moreover, exposure to 100 mg/L SiO2NPs significantly upregulated the expression SOD, HSP70, IL-1β, IL-8, and TNF-α genes in the hepatic tissues as compared to the control group. Exposure of fish to 20 mg SiO2NPs/L significantly increased the mRNA expression levels of IL-12 in both the gills and liver tissues. Notably, all tested SiO2NP concentrations significantly upregulated the transcription of CASP3 gene in gills and liver of Nile tilapia as compared to the control group. Interestingly, varying histopathological alterations in renal, hepatopancreatic, and branchial tissues were observed to be correlated to the tested SiO2NP concentrations. In conclusion, our results provide additional information on the toxic impacts of SiO2NPs in Nile tilapia at the hematological, tissue, and molecular levels.
Highlights
Engineered nanomaterials (ENMs) are increasingly being manufactured due to their wide range of applications in various industrial products [1]
transmission electron microscopy (TEM) images show the morphological information of the SiO2NPs used in the present study; an irregular spherical shape was found, with a relatively uniform size distribution (Figure 1A)
The spectroscopic composition analysis by energy-dispersive X-ray spectroscopy (EDX) demonstrated silicon and oxygen elements in the constituents of the SiO2NP sample used in the present study (Figure 1C)
Summary
Engineered nanomaterials (ENMs) are increasingly being manufactured due to their wide range of applications in various industrial products [1]. SiO2NPs are widely used for various agricultural purposes [9] and in industrial processes such as coatings and paintings [10], printing toners and polishing materials [11], and in medicinal and analytical applications [12]. Despite their aforementioned beneficial uses, the emergence of SiO2NPs in the aquatic environment can induce serious toxicological consequences. In this regard, investigations showed the toxic impacts of SiO2NPs on various fish species. Reports in zebrafish (Danio rerio) showed that SiO2NPs caused DNA fragmentation and alterations to antioxidant enzymatic mechanisms [19], had toxic effects on embryonic development [20,21], and led to oxidative stress [22,23] and behavioral neurotoxicity [24]
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