Evaluation of cyto-genotoxicity biomarkers, changes in histology and antioxidant defense system of Oreochromis niloticus induced by the industrial effluents

Protective effects of Marinobacter nauticus strain GH3 exopolysaccharide on the Oreochromis niloticus model for Alzheimer's disease

Marinobacter nauticus strain GH3 was isolated from the Red Sea, Sharm Elshiekh, and classified according to cultural attributes, biochemical properties, and the analysis of genetic relationships using 16 S rRNA sequences. A substantial proportion of exopolysaccharides (EPS) in GH3-EPS contained a sulfate content of 25.4%, uronic acid (12.18%), and N-acetylglucosamine (13.6%). The composition of monosaccharides in this fraction consists of glucose, glucoronic acid, arabinose, and xylose by 2:4:3:3, respectively. SEM showed a flower-like shape with white bundles on the GH3-EPS surface. GH3-EPS enhancement of the RAW264.7 macrophage line RAW 264.7 ATTC number J774 cell proliferation via MTT assay for cell viability. GH3-EPS had a high stimulation effect on releasing TNF-alpha and IL-10. Followed by its effect against cyclooxygenase (COX-2) and lipoxygenase (LOX), with IC50s of 14.74 and 19.4 µg/ml, respectively. Antioxidant activity was evaluated for GPx-4, GSS, and MDA with highly significant results, and for DPPH, ABTS, and iron chelating with IC50 (43.51, 31.27, and 84.96 µg/ml, respectively). AChE was inhibited by a mean of 52.92 ± 4.54 and 68.22 ± 5.64 µg/ml. In a fish animal model, GH3-EPS demonstrated a positive treatment effect for AD, supporting biochemical studies, histopathology for some brain parts, and toxicity.

The toxic effects of tetracycline exposure on the physiological homeostasis of the gut-liver axis in grouper

Antibiotic residues, such as tetracycline (TET), in aquatic environments have become a global concern. The liver and gut are important for immunity and metabolism in aquatic organisms. In this study, juvenile groupers were subjected to 1 and 100 μg/L TET for 14 days, and the physiological changes of these fish were evaluated from the perspective of gut-liver axis. After TET exposure, the liver showed histopathology, lipid accumulation, and the elevated ALT activity. An oxidative stress response was induced in the liver and the metabolic pattern was disturbed, especially pyrimidine metabolism. Further, intestinal health was also affected, including the damaged intestinal mucosa, the decreased mRNA expression levels of tight junction proteins (ZO-1, Occludin, and Claudin-3), along with the increased gene expression levels of inflammation (IL-1β, IL-8, TNF-α) and apoptosis (Casp-3 and p53). The diversity of intestinal microbes increased and the community composition was altered, and several beneficial bacteria (Lactobacillus, Bacteroidales S24-7 group, and Romboutsia) and harmful (Aeromonas, Flavobacterium, and Nautella) exhibited notable correlations with hepatic physiological indicators and metabolites. These results suggested that TET exposure can adversely affect the physiological homeostasis of groupers through the gut-liver axis.

Sodium dodecylbenzene sulphonate (SDBS) present in detergents: action on the gills, skin, and blood of D. rerio fish

1. Sodium dodecylbenzene sulphonate (SDBS) is one of the surfactants used worldwide in detergents which, due to high residual discharges, has great potential to cause ecotoxicological impacts. Therefore, the sublethal effects of SDBS on the gills and skin of male Danio rerio fish were investigated.

2. The fish were distributed into three groups: GC (control), GT1 (0.25 mg/L of SDBS), and GT2 (0.5 mg/L of SDBS) and exposed for 21 days. After the experiment, histopathological analyses of the gills, histochemical analyses (counting of mucous cells), and biochemical analyses (antioxidant defense enzyme analysis, SOD, and CAT) were conducted.

3. A significant increase (p < 0.05) in the incidence of circulatory disorders, progressive, and regressive alterations occurred in the GT1 and GT2 groups. Due to these changes, the total histopathological index of the gills was higher in these groups. Mucous cells in the gills and skin increased. There was an increase in SOD activity and a reduction in CAT activity in these groups. Haematology revealed neutrophilia and lymphocytosis in the blood of GT1 and GT2.

4. The results clearly demonstrate that a 21-day exposure to SDBS causes severe morphophysiological damage to the gills, skin, and blood of D. rerio fish.