Morpho-histochemistry analysis of freshwater planarians Girardia tigrina (Girard, 1850) exposed to sublethal concentrations of Malathion insecticide

Davi Butturi-Gomes, Karim Christina Scopinho Furquim, Maria Izabel Camargo-Mathias, Maria Aparecida Marin-Morales


Due to planarian regeneration capacity, researchers have made efforts in studying its gene regulation, cell and tissue responses. Despite such advances, many aspects of planarian biology and histology, especially for Girardia tigrina species, remain unknown. Thus, in this study, we aimed at analyzing the potencial of G. tigrina as a biological model for ecotoxicological research by firstly characterizing the morphology and histology of healthy individuals and then evaluating the sublethal effects of Malathion, a widely used insecticide in Brazil. We exposed individuals of G. tigrina to two sublethal concentrations of Malathion (0.08 mg L-1 and 0.8 mg L-1) insecticide for 96h, sectioned them, and then exposed the regenerating portions for another 72h. We submitted all material to scanning electron microscopy and to different histological/histochemical light microscopy techniques. Several changes in the treatment groups were present when compared to the control group. In external morphology, the following alterations were noteworthy: malformation and underdevelopment of the blastemas, pores dilation in the epidermis and loss of ventral cilia. Our main results regarding histology, histochemistry and cytochemistry were the disruption of several tissues, characterized by cytoplasmic changes, such as vacuolation, histochemical and nuclear changes, including chromatin marginalization. Thus, we concluded that Malathion, mainly in the lowest concentration tested, has acted on reproductive strategies of the tested organism, in addition to promoting necrosis in different tissues.

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