Efeitos de Piperaceae em Biomphalaria glabrata (Say, 1818)(Mollusca: Planorbidae) / Effects of Piperaceae on Biomphalaria glabrata (Say, 1818) (Mollusca: Plaorbidae)

A esquistossomose é uma doença grave e de evolução crônica, com importante papel sócio-econômico, cuja profilaxia inclui medidas que envolvem saneamento básico, educação sanitária, tratamento de indivíduos infectados e o controle dos caramujos hospedeiros intermediários do Schistosoma mansoni. Uma das medidas mais eficientes para o controle dos caramujos é a aplicação de moluscicidas, sendo os extratos vegetais os mais indicados. As vantagens do uso de extratos vegetais são devidas, principalmente, ao seu baixo custo e baixa ação tóxica para o ambiente. O objetivo deste trabalho foi avaliar a ação de extratos brutos de Piper cubataonum, Piper caldense, Piper cernuum, Peperomia trineura, Peperomia rubricaulis, Peperomia blanda e da substância ativa, ácido caldensínico de Piperaceae em embriões e adultos de Biomphalaria glabrata. Os extratos brutos e a substância ativa foram obtidos de folhas das plantas. Inicialmente todos os extratos e a substância ativa foram testados nas concentrações de 100 ppm e 20 ppm, respectivamente. Procurou-se determinar para cada extrato as concentrações responsáveis pela mortalidade de no mínimo 50% dos espécimes expostos. Os dados de mortalidade de adultos foram submetidos à análise de probito com intuito de estimar a concentração letal para 50% e 90% (CL50 e CL90) da população. Os extratos que apresentaram efeito tóxico em adultos foram P. trineura a 100, 80 e 60 ppm e P. caldense a 100, 80 e 50 ppm. O ácido caldensínico, quando testado em adultos, apresentou efeito tóxico a 20 e 10 ppm. Nas desovas os extratos que demonstraram efeito toxico foram P. trineura a 100, 80, 60 e 50 ppm, P. rubricaulis a 100 e 80 ppm e P. caldense a 100 ppm, apenas para os estádios de blástula, gástrula, e trocófora. Este último extrato apresentou efeito tóxico a 80 ppm somente para blástula e gástrula. P. caldense mostrou-se mais eficiente que P. trineura para causar a mortalidade em B. glabrata a 50 ppm. Os extratos de P. caldense...

Growth changes induced by gamma radiation on Biomphalaria straminea (Dunker, 1848)

Doses of 60Co gamma radiation with 2.5; 5; 7.5; 10; 15; 20; 25; 30; 35; 40; 45; 50; 55; 60; 80; 160; 320 and 640 Gy were applied to 1,080 snails Biomphalaria straminea, an intermediate host of Schistosoma mansoni, divided in groups containing 30 mollusks. In addition, 60 non irradiated snails were kept as control. Fifty percent of the population was kept in colonies (allowing cross fertilization) while the other half was maintained in sexual isolation (allowing self fertilization) and during one month their growth was observed through the daily measurement of the shell diameter. Results showed that after 20 Gy doses the growth in shell diameter of irradiated snails was greater than that of the control group after 30 days. At this dose the snail size was the greatest, among all isolated groups. The 80 Gy doses also induced the final shell diameter of isolated snails to be greater then that observed in the control groups. As this effect was most evident among the isolated snails, a possible hormonal role may have been involved in the observed phenomena, which is under investigation with the objective of identifying any future applications that this could have to schistosomiasis control

Internal defense response in native and exposed biomphalaria Alexandrina snails pretreated with praziquantel or different physical treatments

Biomphalaria alexandrina snails, intermediate hosts of Schistosoma mansoni either native or exposed, were treated with praziquantel or subjected to UV- and gamma-irradiation. The hemocytes count in native snails with different sizes was compared with the hemocytes count in exposed snails at different intervals post exposure. As well, the humoral response of plasma from native and exposed snails was measured by direct hemagglutination assay. The obtained results indicated high significant interrelations between different experimental treatments, non-treated control and different time intervals of the experiment for both native and exposed snails. The interaction between different snail sizes [native] and the experimental treatments was also highly significant, whereas, no significant interaction was observed between the experimental treatments of the exposed snails and the hemocytes count at different intervals post exposure. The hemocytes count of both UV- and gamma-irradiated snails showed slight decrease as compared with the control for both native and exposed snails. Meanwhile, snails treated with praziquantel showed relative increase in hemocytes count in both native and exposed snails as compared with control, UV- and gamma-Irradiated snails. The observed hemagglutination titre of plasma from either native or exposed snails was not considerably changed in all the experimental groups throughout the course of the experiment. It is concluded that the chemical treatment with praziquantel enhance the immune response in both native and exposed B. alexandrina snails, which could affect the development of the infective larvae inside the snails to a great extent. So, praziquantel could be recommended as a potent molluscicidal and larvicidal agent than UV-and gamma-Irradiation

Fecundity changes induced by low-doses of gamma radiation on Biomphalaria straminea (Dunker, 1848)

A population of 420 snails Biomphalaria straminea, an intermediate host of Schistosoma mansoni, received gamma-rays obtained from a 60 Co source in low-doses (0/2,5/5/7,5/10/15/20 and 25 Gy); half population was kept in colonies (allowing cross fertilization) and other half was mantained in sexual isolation (alowing self fertilization). Results showed that 15 Gy stimulates the fertility of both groups but the colonies were more sensitive and at this dose its fertility overpasses the control group dose. The possible hormonal role played in the observed phenomena is under investigation.

Effect of 60CO gamma radiation on Biomphalaria glabrata (Mollusca, Gastropoda) embryos: mortality, malformation and hatching

A study was carried out on the radiosensitivity of Biomphalaria glabrata embryos submitted to doses of 5, 10, 15, 20 and 25 Gy of 60Co during the cleavage, blastula, gastrula, young trochophore and trochophore stages. Mortality, malformation and hatching were the parameters used to evaluate the damage induced by ionizing radiation. Estimated LD(50) values (15 days) showed that the cleavage stage (4.3 Gy) was approximately four times more radiosensitive than the trochophore stage (l7.0 Gy). Susceptibility to malformation induction was higher in the blastula, gastrula and young trochophore stages. Several types of morphogenetic malformations were observed, such as head malformations, exogastrulas, shell malformations, and embryos with everted stomodeum, with nonspecific malformations being the most frequent. The types of malformation induced by radiation probably are not radiation-specific and do not depend on the dose applied. The dose of 15 Gy was sufficient to greatly reduce the number of hatching snails regardless of the embryonic stage irradiated. We conclude that the effect of (60)Co gamma radiation on B.glabrata embryos presented a specific pattern.

Effect of X-ray on the snails of schistosomiasis in Egypt

Biomphalaria alexandrina and Bulinus truncatus snails were exposed to sublethal doses [0, 2, 3, 5, 10 and 20 rad of X-ray]. The survival and reproductive rates of these snails were highly affected by these doses. The maximum survival periods of laboratory populations of Biomphalaria snails were less than those of field ones, which means a high sensitivity of laboratory snails to X-ray. The reproductive capacity of irradiated Biomphalaria and Bulinus snails was highly suppressed and this was interrupted by Schistosomiasis transmission. A deleterious effect of gametogenesis of irradiated Biomphalaria was histologically proved. After 3 weeks of snail irradiation with high dose [40 rad], the hermaphrodite gland became completely evacuated