Fyziologické a molekulární odezvy vodních organizmů na účinky chemických látek

The biochemical and physiological responses of organisms to xenobiotic chemicals have been investigated for many years as general indicators of organism health. These markers have been used in the development of the synthetic pharmaceuticals and screening of effects of environmental pollutant on biological systems, and in clarifying their modes of action. Recently, use of "OMICS" approaches has received great attentions in exploring the effects of chemical contaminants at the molecular level and is one of the rapidly developing areas in the field of toxicology. Use of molecular response within aquatic organisms has been reviewed and are considered as early changes occurring in response to chemical exposure. ZnO NPs are widely used and possess great potentials in food industry and agriculture. Their subsequent release into environment has raised concerns about their potential effects on aquatic organisms. Although, the dietary exposure perhaps is the main route to expose aquatic animals to nanomaterials, the majority of studies are focused on assessment of waterborne exposure. The molecular mechanisms inducing their toxicity on biological system even less investigated. The present study was conducted to explore weather ZnO NPs can be accumulated in internal organs of carp, as a model fish, as well as to assess fish responses to the presence of ZnO NPs in the feed at protein, biochemical, and histological levels. Our results showed nor apparent accumulation of ZnO NPs neither major changes in haematological parameters, lipid peroxidation level, and histology of internal tissues. Our observations showed that 500 mg ZnO NPs per kg of feed caused changes in pathways and the level of proteins associated with cell motility, immune system response, protein synthesis, cell metabolism, and cell survival in intestine as well as it affected the proteins related to immune system in serum. Treated fish underwent these physiological and molecular changes probably attempted to adjust to ZnO NPs as an external stressor. These changes can be considered as compensatory mechanisms to maintenance homeostasis which have an associated energetic cost. If energetic demands to cope with stress exceeds the capacity of limit, then organism's health will be negatively affected. In the second part of study, peracetic acid in tested therapeutic doses (1 and 3 mg L-1 in grass carp and 10 mg L-1 in signal crayfish) caused some histological alterations in gills as well as changes in the activities of antioxidant enzyme in treated animals. It seems that the observed changes were not large enough to induce mortality in treated animals. According our observation after recovery period, it seems that those changes are reversible if it is followed by a sufficient recovery period allowing animals to restore their disturbed homeostasis. However, species-specific differences should be considered while treating more sensitive species. Toward establishing a safe application guideline, more studies will be required to investigate the given issues