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Int J Biol Sci 2013; 9(8):842-852. doi:10.7150/ijbs.6628

Research Paper

Inorganic Polyphosphates Regulate Hexokinase Activity and Reactive Oxygen Species Generation in Mitochondria of Rhipicephalus (Boophilus) microplus Embryo

Amanda Fraga1, Jorge Moraes1,2, José Roberto da Silva1,2, Evenilton P. Costa3, Jackson Menezes1,2, Itabajara da Silva Vaz Jr2,4, Carlos Logullo2,3, Rodrigo Nunes da Fonseca1,2, Eldo Campos1,2✉

1. Laboratório Integrado de Bioquímica—Hatisaburo Masuda, UFRJ, Polo Barreto, Av. São José do Barreto nº 764, São Jose do Barreto, CEP 27971-550, Macaé, RJ, Brazil;
2. Instituto Nacional de Ciência e Tecnologia—Entomologia Molecular, Rio de Janeiro, RJ, CEP 21941-590, Brazil;
3. Laboratório de Química e Função de Proteínas e Peptídeos and Unidade de Experimentação Animal-CBB-UENF, Avenida Alberto Lamego, 2000, Horto, Campos dos Goytacazes, RJ, CEP 28015-620, Brazil;
4. Centro de Biotecnologia e Faculdade de Veterinária, UFRGS, Avenida Bento Gonçalves, 9090, Porto Alegre, RS, C.P. 15005, CEP 91501-970, Brazil.

Abstract

The physiological roles of polyphosphates (poly P) recently found in arthropod mitochondria remain obscure. Here, the possible involvement of poly P with reactive oxygen species generation in mitochondria of Rhipicephalus microplus embryos was investigated. Mitochondrial hexokinase and scavenger antioxidant enzymes, such as superoxide dismutase, catalase, and glutathione reductase were assayed during embryogenesis of R. microplus. The influence of poly P3 and poly P15 were analyzed during the period of higher enzymatic activity during embryogenesis. Both poly Ps inhibited hexokinase activity by up to 90% and, interestingly, the mitochondrial membrane exopolyphosphatase activity was stimulated by the hexokinase reaction product, glucose-6-phosphate. Poly P increased hydrogen peroxide generation in mitochondria in a situation where mitochondrial hexokinase is also active. The superoxide dismutase, catalase and glutathione reductase activities were higher during embryo cellularization, at the end of embryogenesis and during embryo segmentation, respectively. All of the enzymes were stimulated by poly P3. However, superoxide dismutase was not affected by poly P15, catalase activity was stimulated only at high concentrations and glutathione reductase was the only enzyme that was stimulated in the same way by both poly Ps. Altogether, our results indicate that inorganic polyphosphate and mitochondrial membrane exopolyphosphatase regulation can be correlated with the generation of reactive oxygen species in the mitochondria of R. microplus embryos.

Keywords: inorganic polyphosphate, reactive oxygen species, arthropod, mitochondria, scavenger antioxidant enzymes.

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How to cite this article:
Fraga A, Moraes J, da Silva JR, Costa EP, Menezes J, da Silva Vaz Jr I, Logullo C, da Fonseca RN, Campos E. Inorganic Polyphosphates Regulate Hexokinase Activity and Reactive Oxygen Species Generation in Mitochondria of Rhipicephalus (Boophilus) microplus Embryo. Int J Biol Sci 2013; 9(8):842-852. doi:10.7150/ijbs.6628. Available from http://www.ijbs.com/v09p0842.htm