No abstract

In this paper, we have described for the first time a semiquantitative method to evaluate histopathological damage, taking the degree of Neoechinorhynchus buttnerae attachment to the intestinal wall of the tambaqui (Colossoma macropomum), an important species in Brazilian aquaculture, into account. Twelve specimens of tambaqui were collected from a fish farm. Their bowels were removed and divided into seven morphologically distinct portions according to density and distribution of the parasite studies. Fragments from each fraction were histologically processed and analyzed. There was a clear preference on the part of N. buttnerae for the intermediate regions of the intestinal tube, where the highest densities were recorded. The intensity of damage to the host, estimated by calculating the Histopathological Alteration Index (HAI), showed severe and irreversible changes only where the parasite had its proboscis penetrated into the intestine wall.

Benzo[a]pyrene (B[a]P) is a petroleum derivative capable of inducing cancer in human and animals. In this work, under laboratory conditions, we analyzed the responses of Colossoma macropomum to B[a]P acute exposure through intraperitoneal injection of four different B[a]P concentrations (4, 8, 16 and 32 μmol/kg) or corn oil (control group). We analyzed expression of the ras oncogene and the Hypoxia-inducible factor-1 alpha (hif-1α) gene using quantitative real-time PCR. Additionally, liver histopathological changes and genotoxic effects were evaluated through the comet assay. Ras oncogene was overexpressed in fish exposed to 4, 8 of 16 μmol/kg B[a]P, showing 4.96, 7.10 and 6.78-fold increases, respectively. Overexpression also occurred in hif-1α in fish injected with 4 and 8 μmol/kg B[a]P, showing 8.82 and 4.64-fold increases, respectively. Histopathological damage in fish liver was classified as irreparable in fish exposed to 8, 16 and 32 μmol/kg μM B[a]P. The genotoxic damage increased in fish injected with 8 and 16 μmol/kg in comparison with the control group. Acute exposure of B[a]P was capable to interrupt the expression of ras oncogene and hif-1α, and increase DNA breaks due to tissue damage.