Morpho-Physiological Alterations In Biomphalaria glabrata Say, 1818 (Pulmonata, Planorbidae) Experimentally Infected With Echinostoma paraensei Lie And Basch, 1967 (Trematoda, Echinostomatidae)

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2020-06-25T18:20:31Z No. of bitstreams: 1 2012 - Victor Menezes Tunholi Alves.pdf: 4892646 bytes, checksum: dd22f6fc221412b2e9ad95acd60388d4 (MD5) Made available in DSpace on 2020-06-25T18:20:31Z (GMT). No. of bitstreams: 1 2012 - Victor Menezes Tunholi Alves.pdf: 4892646 bytes, checksum: dd22f6fc221412b2e9ad95acd60388d4 (MD5) Previous issue date: 2012-02-27 Funda??o Carlos Chagas Filho de Amparo ? Pesquisa do Estado do RJ - FAPERJ Parasites belonging to the Echinostoma genus are characterized by having a complex biological cycle, with two intermediate hosts and a final habitat restricted to the intestinal lumen of the definitive hosts. These hosts include aquatic birds, mammals (including humans) and occasionally some reptile and fish species. Their first intermediate hosts are freshwater snails, into which the miracidia actively penetrate for development of the next three stages (sporocysts, rediae and cercariae). Freshwater crustaceans, amphibians, fish and snails act as the second intermediate hosts, enabling the formation of metacercariae, the infective larval stage to the definitive host. In this work, Biomphalaria glabrata specimens were experimentally infected with different doses (5 or 50) of E. paraensei miracidia. The snails were dissected one, two, three and four weeks after infection to collect the hemolymph, shells and tissues (gonad-digestive gland complex- GDG). During this period, the snails? oviposition was observed. In the hemolymph, the concentrations of total proteins, urea, uric acid, cholesterol and triglycerides were measured, as well as the activities of the transaminases (ALT and AST). In the tissues, the levels of neutral lipids (fatty acids, triglyceride, cholesterol and esterified cholesterol) were measured, and in the shells the CaCO3 content was quantified. Significant differences were observed in the bioenergy state of the snails infected with both miracidium doses in relation to the control group (not infected), probably because of the intense formation of glucogenic amino acids from the protein catabolism in response to the stress generated by the parasites. Because of the high energy consumption of the infected snails, it is possible that the anaerobic metabolism becomes more active, culminating in the accumulation of organic acids that reduce the pH of the hemolymph, thus explaining the significant increase in calcemia. In parallel, accentuated decreases in the calcium levels in the shells were found in the snails infected by both miracidium doses (5 and 50), which coincided with the peak calcemia in these specimens. Drastic declines in the total protein concentration in the hemolymph were observed in the infected snails, related to the probable increase of the activities of the transaminases (ALT and AST), an effect also caused by the appearance of rediae and corroborated by the accumulation of uric acid and urea. Additionally, the significant alteration of the lipid profile of the infected snails indicates intense utilization of lipids as a substrate both by the intermediate host and the parasite, suggesting the probable participation of lipids in the energy and structural metabolism of both organisms. The results observed in this study indicate that infection with 5 or 50 E. paraensei miracidia caused considerable metabolic changes in B. glabrata, with the snails exposed to the higher number of miracidia suffering greater damage. Com ciclo biol?gico complexo, os parasitos pertencentes ao g?nero Echinostoma, caracterizam-se por apresentar o h?bitat restrito ? luz intestinal dos hospedeiros definitivos, na qual se destacam as aves aqu?ticas, mam?feros, incluindo o homem, e ocasionalmente algumas esp?cies de r?pteis e peixes. Possuem como primeiro hospedeiro intermedi?rio moluscos l?mnicos, onde os mirac?dios penetram ativamente e desenvolvem at? as fases de cerc?rias e crust?ceos, anf?bios, peixes e moluscos l?mnicos como segundo hospedeiro intermedi?rio onde ocorre a forma??o de metacerc?rias, fase infectante ao hospedeiro definitivo. Neste estudo, Biomphalaria glabrata foi infectada com diferentes doses miracidiais (5 ou 50) de E. paraensei e ap?s uma, duas, tr?s e quatro semanas de infec??o os moluscos foram dissecados para a coleta da hemolinfa, conchas e tecidos (complexo g?nadagl?ndula digestiva- GGD). Observou-se a oviposi??o dos moluscos. Na hemolinfa foram dosadas prote?nas totais, ur?ia, ?cido ?rico, c?lcio, colesterol e triacilglicerol, bem como as atividades das transaminases (ALT e AST). Nos tecidos foram mensurados os conte?dos de lip?deos neutros (?cidos graxos, triacilglecerol, colesterol e colesterol esterificado) e nas conchas, quantificados os conte?dos de carbonato de c?lcio (CaCO3). Diferen?as significativas foram observadas no estado bioenerg?tico dos moluscos infectados com ambas as doses miracidiais em rela??o ao grupo controle (n?o-infectado), provavelmente em consequ?ncia da intensa forma??o de amino?cidos gliconeog?nicos a partir do catabolismo prot?ico em resposta ao estresse gerado pelo parasitismo. O aumento da calcemia pode ser justificado devido ao alto consumo energ?tico nos moluscos infectados, onde o metabolismo anaer?bico pode estar mais ativo culminando com o ac?mulo de ?cidos org?nicos que diminuem o pH da hemolinfa. Simultaneamente, acentuados decr?scimos dos conte?dos de c?lcio nas conchas foram constatados em B. glabrata infectadas por ambas as doses miracidiais (5 e 50) de E. paraensei, o que coincidiu com o pico da calcemia nestes mesmos organismos. Diminui??es no conte?do de prote?nas totais na hemolinfa dos organismos infectados foram observadas, relacionando-se com o prov?vel aumento das vias gliconeog?nicas. Este consumo prot?ico ? confirmado pelo aumento das atividades das transaminases (ALT e AST), efeito tamb?m decorrente ao aparecimento de r?dias no molusco, bem como, ratificado pelo ac?mulo de ?cido ?rico e ur?ia. Aumentos significativos na oviposi??o tamb?m foram evidenciados. Em adi??o, a significativa altera??o no perfil lip?dico dos moluscos infectados indica intensa utiliza??o desse substrato tanto pelo hospedeiro intermedi?rio quanto pelo parasito, sugerindo sua prov?vel participa??o no metabolismo energ?tico e estrutural. Os resultados observados neste estudo indicam que a infec??o com cinco ou 50 mirac?dios de E. paraensei provocou consider?veis altera??es metab?licas em B. glabrata, sendo que os moluscos expostos a maior carga miracidial apresentaram os maiores danos, caracterizando uma resposta dose-dependente.