Calcium- regulated fusion of yolk granules is important for yolk degradation during early embryogenesis of Rhodnius prolixus Stahl

• Autor(a) principal: Ramos, Isabela Barbosa
• Data de Publicação: 2007
• Outros Autores: Miranda, Kildare Rocha de, Souza, Wanderley de, Santos, Danielle Maria Perpétua de Oliveira, Lima, Ana Paula Cabral de Araújo, Sorgine, Marcos Henrique Ferreira, Machado, Ednildo de Alcântara
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional do INMETRO
• Texto Completo: http://hdl.handle.net/10926/1651

This study examined the process of membrane fusion of yolk granules (YGs) during early embryogenesis of Rhodnius prolixus. We show that eggs collected at days·0 and 3 after oviposition contain different populations of YGs, for example day-3 eggs are enriched in large YGs (LYGs). Day-3 eggs also contain the highest free [Ca2+] during early embryogenesis of this insect. In vitro incubations of day-0 YGs with [Ca2+] similar to those found in day-3·eggs resulted in the formation of LYGs, as observed in vivo. Fractionation of LYGs and small YGs (SYGs) and their subsequent incubation with the fluorescent membrane marker PKH67 showed a calciumdependent transference of fluorescence from SYGs to LYGs, possibly as the result of membrane fusion. Acid phosphatase and H+-PPase activities were remarkably increased in day-3 LYGs and in calcium-treated day-0 LYGs. Both fractions were found to contain vitellins as major components, and incubation of YGs with calcium induced yolk proteolysis in vitro. Altogether, our results suggest that calcium-induced membrane fusion events take part in yolk degradation, leading to the assembly of the yolk mobilization machinery.