The Effects of Pesticides on Dictyostelium Cholinesterase, from Basic to Applied Research

Numerous organisms have been proposed as biotests in standardised laboratory procedures to evaluate contamination caused by pesticides. In this context, protozoa are regarded as a valuable assay to be exploited in laboratory investigations because of their fundamental features. Due to their nature as eukaryotic cells/organisms, protozoa exhibit a relatively simple organisation and a high degree of specialisation. As eukaryotic organisms, protozoa behave like animals, responding directly to environmental stimuli, but, as single-cells, they are more sensitive to environmental changes than the cells of higher organisms. Like microorganisms generally, protozoa multiply through short cell-cycles and this makes it possible to detect the effects of pesticides on large and genetically homogeneous cell populations and on their progeny as well. These peculiarities of protozoa are more interesting if we consider how the test on protozoa can assuage public opinion, more and more sensible to bioethical matters and meet the requests of both the ICCVAM and the ECVAM for compliance with the 3Rs strategy. Furthermore, it is important to highlight that the identification of molecules functionally related to neurotrasmission in protozoa (such as the GABAergic system in Paramecium and Dictyostelium, the nitrergic system in Paramecium and the cholinergic system in Paramecium, Dictyostelium and Euplotes, through which they can react to environmental stress, like the molecules of macroinvertebrate and vertebrate models) provides a new method for using protozoa in neurotoxicity tests and as ecological indicators in biomonitoring. This paper will focus on the inhibition of Dictyostelium ChE activity as a biomarker of exposure to neurotoxic pesticides and how this biomarker can be used in the field for the pre-chemical screening of estuarial zones. The area investigated was the western coast of Liguria, an area stretching from Genoa to the French border, whose economy is based on greenhouse market gardening, olive oil production and summer tourism. In this area, it is important to convince people of the need for continuous biomonitoring to maintain the balance between intensive farming and tourism on the one hand and environmental and public health on the other for sustainable development.