Role of Acid Hydrolases During Follicular Atresia in a Vector of Chagas´disease.

LEYRIA, J; AGUIRRE, S.A.; FRUTTERO, L.L.; CARLINI, C.R.; RUBIOLO, E.R.; CANAVOSO, L.E.

Foz do Iguaçu.

Otro; XLI Reunião Anual da Sociedade Brasileira de Bioquímica e Biologia Molecular.; 2012

Sociedade Brasileira de Bioquímica e Biologia Molecular

In insects, the main yolk protein precursor, vitellogenin (Vg), is taken up by developing oocytes, stored as vitellin (Vt) in specialized structures and degraded throughout embryogenesis. Under unfavourable nutritional conditions, biochemical and cellular changes take place in the ovarian tissue and early degradation of vitellin (Vt) and the atresia of some follicles proceed until resorption. In some species, the changes accomplished during atresia are elicited to promote the recycling of proteins to sustain younger follicles. In this study, we have explored biochemical changes that take place during the process of follicular atresia induced by a nutritional deficit in the hematophagous Dipetalogaster maxima, a vector of Chagas’ disease. We have emphasized in the roles of two acid hidrolases, cathepsin D (CD) and acid phosphatase (AP). The study included assays of western-blot, the measurement of enzyme activities, immunofluoresce as well as in vitro assays of Vt proteolysis employing specific inhibitors of CD and AP. Results showed that proteolysis of Vt occurred gradually during the transition from vitellogenesis to follicular atresia. Higher activities of AP and CD were registered at early and late atresia, in comparison to pre-vitellogenesis and vitelogenesis. In vitro assays showed that AP is important in promoting Vt degradation, which in turn was mediated by CD. Altogether, the biochemical changes exhibited during follicular atresia in D. maxima could reflect the ability of the ovarian tissue to face a new vitellogenic cycle if nutritional conditions improve. The results also provide a better understanding of the biology of reproduction o Chagas’ disease vectors.