Biochemical and Cellular Characterization of Follicular Regression in Dipetalogaster maxima, a Vector of Chagas’ Disease

AGUIRRE, S.A.; LEYRIA, J.; FRUTTERO, L.L.; FREDE, S.; SETTEMBRINI, B.P.; RUBIOLO, E.R.; CANAVOSO, L.E.

Foz do Iguaçu, Paraná

Otro; XXXIX Reunião Anual da Sociedade Brasileira de Bioquímica e Biologia Molecular; 2010

Sociedade Brasileira de Bioquímica e Biologia Molecular

In some insects, a successful reproduction cycle needs a compromise between two processes: vitellogenesis and follicular regression. During the regression phase, several changes promote atrophy of some follicles and oocyte resorption. In this work, we have analyzed the biochemical and cellular changes during early and late stages of follicular regression in Dipetalogaster maxima, a vector of Chagas’ disease. The study included the measurement of circulating vitellogenin (Vg) as well as vitellin (Vt), total lipids (L) and carbohydrates (CH) in ovary. Proteolytic events were assessed by determining the activity of total cathepsins and cathepsin D in ovary. Cellular approaches included scanning electron microscopy, fluorescent microscopy, immunohistochemistry and in vivo assays with monodansylcadaverin, a marker of autophagy. The regression phase was characterized by a significant decrease of Vg levels and its uptake by oocytes. Most ovarioles were poorly developed, contained small metabolic resources (L and CH) and showed terminal atretic follicles. During early regression, a gradual activation of cathepsin D was also observed. At a cellular level, an intense phagocytic activity and cell death patterns compatible with apoptosis and autophagy were observed. We concluded that in D. maxima, follicular regression is a physiological and gradual event that induces oocyte resorption to supply nutrients to younger follicles.