Morphological and biochemical changes during the transition from vitellogenesis to follicular regression in the hematophagous Dipetalogaster maxima (Hemiptera: Reduviidade).

AGUIRRE SA; FRUTTERO LL; LEYRIA J; SETTEMBRINI BEATRIZ P; CARLINI CR; RUBIOLO ER; CANAVOSO LE

Foz de Iguazu

Congreso; (XXXIX Annual Meeting of The Brazilian Biochemistry and Molecular Society; 2010

Sociedad Brasileña de Bioquimica y Biología Molecular

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.,Rubiolo, E.R., Canavoso, L.E. Dpto. Bioquímica Clínica, CIBICI-CONICET, Fac. Cs. Químicas, UNC, Argentina, 2 Museo Argentino de Cs. Naturales-CONICET, Argentina. 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 of ovarioles were poor-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.   Key words: Vitellogenesis, follicular regression, metabolic resources, Dipetalogaster maxima.