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Changes in oogenesis of Rhodnius prolixus during the infection of the fungi Aspergillus Niger.
Belmonte, R.1; Medeiros, M.N.1; Medeiros, L.N.2; Kurtenbach, E.2; Masuda H.3; Machado E.A.1
1 Laboratorio de Entomologia Médica, IBCCF, UFRJ
2 Laboratorio de Expressao Heterologa de Proteinas, IBM, UFRJ
3 Laboratorio de Bioquimica de Insetos, IBM, UFRJ
Insect oogenesis is a well-coordinated process that basically involves the synthesis of yolk protein and its uptake by developing follicles. The resorption of follicles is a strategy to reallocate resources into others metabolic pathways. Many models have showed that resorption is induced by immune challenge but the molecules involved in this signaling still unknown.
Insects have an immune system that is based in physical, cellular and humoral constituents. The humoral constituent comprises the synthesis of peptides and proteins with antimicrobial activity. Many of these antimicrobial peptides have been characterized as a response for bacterial infection, but little is known about the antifungal peptides.
Our main goal in this work is to access the physiological changes of adult females of Rhodnius prolixus inoculated with Aspergillus niger conidia. The haemolymph was also studied with SDS-PAGE and methods to measure protein concentration during the fungal infection.
Using the quantity of 105 conidia via haemocoel the pathogenicity was low (mortality equal to control). Females infected with these fungi had a slower oviposition rhythm with the total number of eggs laid lower them control. After dissection of bugs followed by observation in a stereomicroscope we could notice follicles in the process of resorption and immune nodules (cellular immune response) 48 hours post infection.
We are also looking for antifungal activity in the haemolymph, as preliminary tests showed a strong reduction in the growth of the fungi incubated with the haemolymph of the infected females.
The higher protein concentration of the infected insects haemolymph along with a slower weight loss supports the idea that they are saving up resources to fend off the infection.
The results obtained so far indicated that there is a correlation between the immune and the reproductive system and we intend to characterize the molecules that are involved in this correlation. It is also our objective to isolate and characterize immune peptides with antifungal actitvity.
Supported by CNPQ, FAPERJ and PRONEX
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