engleski

Efflux Pump Activity in Enchytraeidae

A multixenobiotic resistance mechanism (MXR) is a cellular detoxification mechanism present in all organisms, including microbes, plants, invertebrates and vertebrates. It is mediated by the activity of the ATP‐binding cassette (ABC) transporters. The MXR proteins (efflux pump) transfer certain groups of xenobiotics out of the cell and keep the intracellular concentration of these compounds low. The enchytraeids are the ecologically relevant soil organisms, which play an important role in an organic matter decomposition and soil bioturbation. In the phylum Annelida MXR, an activity was discovered mainly in the earthworm species, but there were no enchytraeid species discovered. For the identification of an efflux pump activity, fluorescent substrates are often used. In case of an MXR system inhibition, the concentration of substrate in the cells increases, and this can be seen as a rise in fluorescence. Two enchytraeid species (Enchytraeus albidus and E. crypticus) were exposed to an ISO test water, with or without specific chemosensitizers, at various concentrations. Subsequent to a pretreatment, they were exposed to the fluorescent substrates, Rhodamine B (RhB) or Rhodamine 123 (Rh123). The amount of RhB and Rh123 in the samples was measured using a spectrofluorometer. Using the RhB and R123 as a fluorescent substrate, it could be seen that different substrates and chemosensitizers exert an effect on the amount of fluorescence in the enchytraeids. The ability of enchytraeids to remove the xenobiotics from the cells will greatly impact the final detrimental effects. Determining a presence and function of the MXR in enchytraeids can help us understand the consequences of MXR inhibition at the population and ecosystem level. This study demonstrates that the enchytraeids, as a model species in the terrestrial ecotoxicology, possess an MXR activity and that different substrates and chemosensitizers have an impact on it. Therefore, it can be presumed that the xenobiotics present in the environment will have an effect on an MXR system as well. Due to the influence of an MXR activity on the bioaccumulation and toxicity of various compounds, the assessment of an 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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