engleski

Unraveling the hazards of selenium trace elements to earthworm immunity, from genes to cells

Objectives: It is widely known that selenium (Se) supplementation has beneficial effects on the immune response ; however it also possesses potential risk of toxicity. Its toxicity depends on its chemical form, and applied concentrations. The aim of this study was to estimate the impact of increased concentrations of different forms of Se on the cellular immune components (so called coelomocytes) of earthworms. Methods: Eisenia andrei earthworms were exposed to various concentrations of two different forms of Se, selenite and selenate. By means of flow cytometry Annexin V positivity, caspase 3 activity, and mitochondrial membrane integrity were assessed to evaluate the coelomocyte survival in earthworms exposed to high selenium concentrations. Modulation of immune (TLR, coelomic cytolytic factor, lysenin, lysozyme) and stress-related genes (catalase, Cu/Zn SOD, MnSOD, metallothionein) upon selenium exposure was measured by qPCR. Results: Higher concentrations of selenate caused increased Annexin positivity, induced caspase 3 activity and decreased mitochondrial membrane potential of coelomocytes. Thus, these results indicate an apoptotic-like cell death in the exposed earthworms. In contrast, higher concentrations of selenite evoked a drop off of several immune (lysenin, lysozyme) and stress- related (MT, Cu/ZnSOD, MnSOD) genes in this soil-sentinel organism. Conclusions: Both Se forms showed significant impact on the measured cellular and genetic parameters in earthworms, indicating the disruption of immune and stress homeostasis. Obtained results can serve as basis for further studies on Se effects and will help in including different aspects necessary for understanding of Se impact on cellular immune components of living organisms.

selenium ; earthworm immunity ; gene expression ; coelomocytes

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