Biological targets of neurotoxic pesticides analysed by alteration of developmental events in the Mediterranean sea urchin, Paracentrotus lividus.

Biological effects of neurotoxic insecticides widely used for agricultural purposes were studied using the early development of the Mediterranean sea urchin Paracentrotus lividus as a model. These compounds, dispersed as aerosols or powders in agricultural regions near to the coast, may affect the health of organisms in the marine environment. The biological effects of Basudin (an organophosphate compound containing 20% Diazinon), Diazinon (Dzn, a thionophosphate), Carbaryl and Pirimicarb (carbamates) on the early phases of sea urchin development were thus investigated. Morphological, biochemical, histochemical and immuno histochemical analyses were performed both during embryo and larval development. For the morphological effects on fertilisation and first cleavages, the effective concentration of insecticides was found to be 10(-4) M, while for further stages concentrations between 10(-5) and 10(-7) M were effective: 10(-3) M of any of these insecticides totally arrested development. During embryonic development, the treatment with organophosphates slowed the rate of early mitotic cycles down, affected nuclear and cytoskeletal status as well as DNA synthesis. From the gastrulation stage onwards, the main effects were exerted on the rate of primary mesenchyme cells migration, larval size, perioral arm length, and acetylcholinesterase activity distribution, thus deregulating the cholinergic system, which modulates cell-to-cell communication mediated by the signal molecule acetylcholine.