Germ band retraction as a landmark in glucose metabolism during Aedes aegypti embryogenesis
1 Laboratório de Química e Função de Proteínas e Peptídeos and Laboratório de Biotecnologia-CBB-UENF, Av Alberto Lamego, 2000, Horto, CEP 28015-620 Campos dos Goytacazes, RJ, Brazil
2 Centro de Biotecnologia do Estado do Rio Grande do Sul and Faculdade de Veterinária, UFRGS, Av Bento Gonçalves 9500, CP 15005, 91501-970, Porto Alegre, RS, Brazil
3 Laboratório de Fisiologia e Controle de Artrópodes Vetores, IOC - Fiocruz, Av. Brasil 4365, CEP 21045-900 Rio de Janeiro, RJ, Brazil
4 Laboratório de Entomologia, IBEx, Rio de Janeiro, RJ, Brazil
5 Instituto de Bioquímica Médica - UFRJ/Macaé and Núcleo em Ecologia e Desenvolvimento Sócio-Ambiental de Macaé-NUPEM-UFRJ, Av São José do Barreto s/n, CEP 27971-550, São José do Barreto, Macaé, RJ, Brazil
BMC Developmental Biology 2010, 10:25 doi:10.1186/1471-213X-10-25Published: 25 February 2010
The mosquito A. aegypti is vector of dengue and other viruses. New methods of vector control are needed and can be achieved by a better understanding of the life cycle of this insect. Embryogenesis is a part of A. aegypty life cycle that is poorly understood. In insects in general and in mosquitoes in particular energetic metabolism is well studied during oogenesis, when the oocyte exhibits fast growth, accumulating carbohydrates, lipids and proteins that will meet the regulatory and metabolic needs of the developing embryo. On the other hand, events related with energetic metabolism during A. aegypti embryogenesis are unknown.
Glucose metabolism was investigated throughout Aedes aegypti (Diptera) embryonic development. Both cellular blastoderm formation (CBf, 5 h after egg laying - HAE) and germ band retraction (GBr, 24 HAE) may be considered landmarks regarding glucose 6-phosphate (G6P) destination. We observed high levels of glucose 6-phosphate dehydrogenase (G6PDH) activity at the very beginning of embryogenesis, which nevertheless decreased up to 5 HAE. This activity is correlated with the need for nucleotide precursors generated by the pentose phosphate pathway (PPP), of which G6PDH is the key enzyme. We suggest the synchronism of egg metabolism with carbohydrate distribution based on the decreasing levels of phosphoenolpyruvate carboxykinase (PEPCK) activity and on the elevation observed in protein content up to 24 HAE. Concomitantly, increasing levels of hexokinase (HK) and pyruvate kinase (PK) activity were observed, and PEPCK reached a peak around 48 HAE. Glycogen synthase kinase (GSK3) activity was also monitored and shown to be inversely correlated with glycogen distribution during embryogenesis.
The results herein support the hypothesis that glucose metabolic fate changes according to developmental embryonic stages. Germ band retraction is a moment that was characterized as a landmark in glucose metabolism during Aedes aegypti embryogenesis. Furthermore, the results also suggest a role for GSK3 in glycogen balance/distribution during morphological modifications.