Helminth parasite infections are associated with predominant Th2-type cytokine responses, and parasite glycoconjugates have been recognized as partially responsible for such immune bias. It has been proved that Echinococcus granulosus evokes a Th2-type cytokine pattern characterized by a high production of IL-4, IL-5, IL-6 and IL-10, and no or mild IFN-γ levels in animal models and in patients with cystic echinococcosis, respectively. Here, we show that E4(+) (a glycoconjugate-enriched fraction from E. granulosus protoscolex) stimulated the secretion of a high concentration of IL-6, followed by IL-10 and TNF-α by normal peritoneal B cells. We determined that E4(+) bound to the surface of peritoneal B cells and induced their activation and, also, triggered the differentiation of peritoneal B cells into IgM-, IgG2b- and IgG3-secreting cells in a T-independent way. Interestingly, the IgM released by E4(+) -stimulated peritoneal B cells from normal mice recognized protoscolex antigens. Results showed that, after the encounter with antigens from E. granulosus protoscolex, peritoneal B cells are a source of Th2-type cytokines and polyclonal antibodies, some of which recognize parasite antigens, suggesting that peritoneal B cells can condition the outcome of the infection.

This study examines the survival, mortality, morphology and swimming ability of tadpoles exposed to the organophosphate chlorpyrifos (nominal concentrations of 10, 100, 200 e 400 μg L-1) for 192 h. Odontophrynus carvalhoi tadpoles were used as a biological model. Our findings include decreased survival rates of tadpoles primarily at the highest pesticide concentration (400 μg L-1) and deformities in the caudal muscles, causing spasms and tremors. Tadpoles exposed to chlorpyrifos (10 μg L-1) had the lowest swimming speed compared with that of the control group. Tadpoles the other concentrations (100, 200 and 400 μg L-1) were not evaluated since none of the survived 192 h exposure in concentrations above 10 μg L-1. These adverse effects indicate that this organophosphate can affect the survival of tadpoles even in small doses, compromising the local population.

No abstract

Chlorpyrifos is an organophosphate insecticide widely used and it acts as an inhibitor of cholinesterases, overstimulating the nerve endings. This study analyzed the genotoxic effect of the organophosphate insecticide Chlorpyrifos upon the induction of micronucleated erythrocytes in the blood of Odontophrynus carvalhoi Brazilian neotropical tadpoles submitted to four different nominal concentrations of this insecticide (10, 100, 200 e 400 mg L-1) during 96 hours. The tadpoles were anesthetized, euthanized and their blood was collected through cardiac puncture and later on cyto smears were performed and stained with May Grunwald Giemsa. The frequencies of micronucleated erythrocytes were determined at different periods of exposure (24h, 48h e 96h) through the analysis of 1000 erythrocytes for each tadpole. The tadpoles that were submitted to the Chlorpyrifos showed high frequencies of genetic changes (micronuclei) when compared with the negative control. The differences in the frequencies of the micronuclei registered after 48 hours of exposure were statistically significant (p<0.05). Thus, it can be concluded that tadpoles of O. carvalhoi were susceptible to genetic alterations induced by the use of the commercial formulation of chlorpyrifos (Klorpan®), showing a clastogenic effect in the erythrocytes of this species. The use of this species as an animal model for genotoxic studies has shown promise.

No abstract