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Responses of oxidative stress, genotoxicity and immunotoxicity as biomarkers in Theba pisana snails dietary exposed to silver nanoparticles

Radwan, M. A., El-Gendy, K. S., Gad, A. F., Khamis, A. E., Eshra, E. H.
Chemistry in ecology 2019 v.35 no.7 pp. 613-630
DNA, Theba pisana, X-ray diffraction, absorption, biomarkers, catalase, cell death, cytogenetics, ecotoxicology, genotoxicity, glutathione, glutathione transferase, hemocyanin, humans, immunotoxicity, leaf extracts, lectins, lipid peroxidation, micronucleus tests, monophenol monooxygenase, nanoparticles, nanosilver, nontarget organisms, oxidative stress, peroxidase, phagocytosis, radishes, risk assessment, snails, superoxide anion, terrestrial ecosystems, transmission electron microscopy, ultraviolet-visible spectroscopy
Silver nanoparticles (AgNPs) are now being of a great interest by ecotoxicological researchers. Their potential hazards to humans and other non-target organisms had led to crucial concerns. In this research, white radish leaf extract was used for the green synthesis of AgNPs. UV–Vis spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD) have been utilised to characterise the biosynthesised AgNPs. Furthermore, the present study aimed to investigate the ecotoxicological effects of 1 mM biosynthesised AgNPs on the land snail, Theba pisana after two weeks of exposure and one week recovery with respect to oxidative stress parameters; lipid peroxidation (LPO), reduced glutathione (GSH), catalase (CAT) and glutathione-S-transferase (GST), cytogenetic parameters; DNA content and micronucleus test, as well as immunological parameters; cell death, phagocytosis, lysosomal membrane stability (LMS), lectins, superoxide anion (O₂⁻) generation, phenoloxidase (PO), peroxidase (POD) and haemocyanin (Hc) were examined. AgNPs have been biosynthesised successfully; the UV–vis spectrum exhibited a single and broad absorption band located between 375 and 415 nm, TEM image shows AgNPs formed were nearly spherical in shape with a mean size of 2.18–19.87 nm and the crystalline nature of nanoparticles was confirmed by XRD. After two weeks exposure, the result showed that AgNPs significantly increased LPO level as well as CAT and GST activities, cell death, cell abnormalities and Hc level, whereas, significant decline was found in DNA and GSH contents, phagocytic activity, LMS, lectins, O₂⁻ generation, POD and PO activities compared to the controls. After a week of recovery, most of the tested biomarkers in AgNP-exposed snails did not completely return to the control levels. The multiple measured parameters could be effectively used as sensitive biomarkers in the risk assessment of contaminants in the terrestrial ecosystem.