Alterations in the skin of Labeo rohita exposed to an azo dye, Eriochrome black T: a histopathological and enzyme biochemical investigation

Abstract

Histopathological changes and alterations in the activity of certain metabolic and antioxidant enzymes were analyzed in the head skin of Labeo rohita, exposed to sublethal test concentrations of the azo dye, Eriochrome black T for 4 days, using 24 h renewal bioassay method. Hypertrophied epithelial cells, increased density of mucous goblet cells, and profuse mucous secretion at the surface were considered to protect the skin from toxic impact of the azo dye. Degenerative changes including vacuolization, shrinkage, decrease in dimension, and density of club cells with simultaneous release of their contents in the intercellular spaces were associated to plug them, preventing indiscriminate entry of foreign matter. On exposure of fish to the dye, significant decline in the activity of enzymes-alkaline phosphatase, acid phosphatase, carboxylesterase, succinate dehydrogenase, catalase, and peroxidase-was associated with the binding of dye to the enzymes. Gradual increase in the activity of lactate dehydrogenase was considered to reflect a shift from aerobic to anaerobic metabolism. On transfer of azo dye exposed fish to freshwater, skin gradually recovers and, by 8 days, density and area of mucous goblet cells, club cells, and activity of the enzymes appear similar to that of controls. Alteration in histopathology and enzyme activity could be considered beneficial tool in monitoring environmental toxicity, valuable in the sustenance of fish populations.

Neuroprotective effects of quercetin produced by an endophytic fungus Nigrospora oryzae isolated from Tinospora cordifolia

“…Tissues were sectioned at 6 μm, and the sections were then stained with periodic acid‐Schiff and counterstained with haematoxylin. The obtained sections were visualized and photographed using a Leica DFC 290 (Leica Microsystems Ltd) at 25× magnification (Gupta et al, 2019; Srivastava et al, 2017).…”

Effective removal of Eriochrome black T by a novel ZnxCu01-xFe2O4/C3N4 composite under simulated visible light irradiation

“…It has been indicated that dyes can be carcinogenic and has mutagenesis owing to the presence of aromatic rings in their structure [9]. In addition, Earlier investigations have reported that direct contact of EBT with skin causes to alterations in metabolic and antioxidant enzymes activities and activates toxic metabolites that generate free radicals in the exposed cells [10,11]. So, it becomes a worldwide concern to control dye emissions and remove dyes from waster liquids.…”