Análise morfométrica do epitélio de revestimento do filamento branquial do guaru (Poecilia vivípara) exposto a frações do extrato da folha e casca do caule de pequi (Caryocar brasiliensis)

Abstract

In the last years, the Brazilian Cerrado has been one of the ecological sites most scientifically explored. Recent studies have proposed the use of the leaf and bark extracts of C. brasiliensis (pequi) as a mollusk-killing agent with the purpose of fighting the intermediary host (Biomphalaria glabrata) of the parasite responsible for schistosomiasis; Schistosoma mansoni. As this mollusk is always near water sources, the impact of this product on freshwater animals is being questioned. ln this sense, we used the gill of the curyhaline fish Poecilia vivípara (guaru), already widely used as a bioindicative of water pollution, to test the toxicity of fractions of leaf and bark extracts of pequi. A sample of 30 adult guarus composing five experimental groups were exposed to aqueous, ethyl-acetate and ethereal fractions of the ]eaf and to the aqueous and ethyl­acetate fractions of the bark or the pequi, during 24 hours. The area and the perimeter of the gill filaments in the basal, intermediate and apical regions were measured. Statistical analyses demonstrated that the area of the experimental groups did not differ from the control. However, the perimeter of the basal and intermediate regions differed significantly from the control, although not impairing the physiologic activities of the gill. Thus, it is suggested that in concentrations of 20 ppm, the extracts tested can be used as mollusk-killers in water sources, with the exception of the aqueous fraction of the leaf.