engleski

Efflux pump activity in Enchytraeidae

Enchytraeids are ecologically relevant soil organisms, which play an important role in organic matter decomposition and soil bioturbation. They live in close contact with the pore water fraction of soil which makes them vulnerable to xenobiotics exposure. MXR proteins (efflux pump) transfer certain groups of xenobiotics out of the cell and keep the intracellular concentration of these compounds low. They are present in all organisms, including microbes, plants, invertebrates and vertebrates. In the phylum Annelida MXR activity was discovered mainly in earthworm species but none enchytraeids. For the identification of MXR system activity fluorescent substrates are often used. In case of MXR system inhibition, the concentration of the substrate in the cells increases, and this can be seen as a rise in fluorescence. Enchytraeids were exposed in distilled and ISO test water, with or without specific inhibitors and inducers at various concentrations for 1 h in the dark. After pretreatment they were exposed to various concentrations of Rhodamine B (RhB) or Rhodamine 123 (Rh123). The measurement of RhB and Rh123 amount in samples were conducted immediately after centrifugation. The samples were kept in dark due to the photo degradation of RhB and Rh123. The amount of RhB and Rh123 in the samples was measured using spectoflourometer. Using RhB and R123 as the fluorescent substrate, it could be seen that different substrates and chemosensitizers have an effect on the amount of fluorescence in the E. albidus and E. crypticus. Some metal nanoparticles and pesticides are ubiquitous environmental toxicants and potential MXR modulators that pose a continuing risk to many non-target species. The ability of enchytraeids to remove the xenobiotics from the cells will greatly impact the final harmful effects. Determining presence and function of the MXR in enchytraeids can help us to understand the consequences of MXR inhibition at the population and ecosystem level. This study shows that enchytraeids, as a model species in terrestrial ecotoxicology, possess MXR activity and that different substrates and chemosensitizers have an impact on it. Therefore, it can be presumed that xenobiotics present in the environment will have an effect on MXR system as well. Due to the influence of MXR activity on bioaccumulation and toxicity of various compounds, the assessment of MXR activity could be a valuable complementary biomarker in ecotoxicological research and risk assessment.

enchytraeids, chemosensitizers, MXR proteins, efflux pump, biomarker

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