Application of the comet test to evaluate the genotoxicity of cadmio in tissue types of species Bombus atratus (Hymenoptera: Bombini)

Abstract

Cadmium (Cd) is a trace metal with high genotoxic potential; can be found as a component of a wide variety of industrialized products, including agrochemicals, both potentiating deleterious effects on non-target entomofauna; especially bees. Thus, to evaluate the genotoxicity of this metal in neotropical bees, bioassays will be performed with workers of the Bombus atratus species. The bees (n = 11, for each group) will be kept in incubator (24N, 26ºC, 70% humidity) for 48 hours in individual boxes. The exposure will be realized by offering a solution contaminated with 1dbp Cd, offered ad libitum. The workers of the control group will be kept under the same conditions but fed with 70% sucrose and uncontaminated distilled water. The bioassays will be performed in replicate. After the exposure period, the fatty body and the pericardial cells that surround the dorsal vessel will be dissected. The material will be submitted to the cellular fractionation to isolate the fraction of cellular nuclei from the tissues that will be studied. From the fractionation of the cell nuclei, the Cometa Assay will be carried out, a methodology that evaluates the damage that occurred in the genetic material in individualized cell nuclei. The slides prepared for the comet assay will be stained and analyzed by photomicroscope. In addition to the characterization of the four stages of chromatin fragmentation, the Damage Index (ID) and the Damage Frequency (FD%) will be calculated. Finally, CASP software will be used as a complementary method to visual classification of comets.