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Inorganic Polyphosphate Characterization on the Early Embryogenesis of Periplaneta americana
Gomes, F.M.a; Motta, L.M.a; Ramos, I.B.a; Santiago, M.F.b; Machado, E.A.a
a - Laboratório de Entomologia Médica, Departamento de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro
b - Laboratório de Neurobiologia Celular e Molecular, Departamento de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro
Inorganic polyphosphate (PolyP) is a linear polymer of tens and even hundreds of orthophosphate (Pi) residues linked by high-energy phosphoanhydride bonds. Some different functions have been described for polyphosphates: ATP substitute, reservoir of Pi, chelator of metal ions, buffer against alkalis and others. Likely a prominent precursor in prebiotic evolution, PolyP is found in nature and in different living groups (bacteria, fungi, protozoa, plants and mammals) and is believed to exist in every living thing. Nevertheless, there is no previous description of polyphosphates in insects.
The present work describes the existence of polyphosphate molecules in the eggs of Periplaneta americana, a cockroach model. Polyphosphate was detected by paper chromatography revealed with ammonium molybdate and toluidine blue and had the variation along the embryogenesis analyzed with DAPI. This same reagent was used for the localization of PolyP with confocal microscopy. Free calcium and Pi variation along the embryogenesis were also analyzed and correlated with the PolyP variation. Finally, electrophoretic assays were used to determine the size distribution of this molecule within the eggs
Paper chromatography suggested significant amounts of Pi and PolyP in the eggs during the first day of embryogenesis. DAPI fluorimetry detected a peak of PolyP in the first 24 hours of embryogenesis and a minimum around the fifth day. Calcium variation seemed to be inversely correlated with the PolyP content. At the same time, Pi variation seemed to be proportional to the PolyP variation. PolyP was preferentially stored inside small yolk granules smaller than 5 µm and concentrated in two mains sizes.
This work was supported by CNPQ, FAPERJ, PRONEX.
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