We have reported that Aedes aegypti female mosquitoes possess a remarkable biological system to survive toxic ammonia concentrations released by blood meal digestion using previously unknown metabolic pathways present in this organism. Specifically, we have found that Ae. aegypti can detoxify ammonia by the same metabolic pathways that nitrogen fixing plants and bacteria use, unlike all other insects that have been studied. Mosquitoes can also use the nitrogen from the amide group of glutamine to produce uric acid as vertebrates do, and more surprisingly, mosquitoes hydrolyze uric acid into urea through the same metabolic pathway that some fish and amphibians use. Since the coordinated operation of these multiple metabolic pathways prevents a lethal ammonia concentration in the mosquito tissues after a blood meal, it impels us to know how these metabolic pathways are interconnected and regulated. Therefore, the main purpose of the grant application is to elucidate the metabolic regulation of nitrogen waste, as well as to analyze the flux of C and N molecules involved in ammonia metabolism in mosquitoes. These studies will be performed using a combination of RNA interference and mass spectrometry techniques. Attempts to control mosquito populations using biorational approaches depend on a thorough understanding of mosquito biology and metabolism. So, if the experiments that we propose are conducted successfully, they will open up new and exciting discoveries that could be applied for the design and implementation of better strategies for mosquito control. The following specific aims will be pursued: 1- Identify the mechanisms involved in the regulation of nitrogen waste in mosquitoes. 2- Investigate the flux of C and N molecules involved in ammonia metabolism in mosquitoes. According to our preliminary data, the metabolic regulation of nitrogen waste appears to be tightly- regulated in Ae. aegypti mosquitoes. Therefore, our objective is to understand how this regulatory mechanism controls the ammonia metabolism in adult female mosquitoes.
Mosquitoes are vectors of etiological agents that cause more than one million deaths annually. In spite of the global efforts to eradicate this serious worldwide problem, the insecticide-resistant mosquitoes, drug- resistant parasites, and socio-politico-economic obstacles, have made the efforts insufficient for controlling the mosquito populations, and therefore the diseases that they transmit. Thus, new control strategies are needed based on the new knowledge of biochemical and physiological process that operate in mosquitoes. We have observed Ae. aegypti females have a powerful biochemical-physiological machine for coping with the toxic ammonia concentrations generated during a blood meal digestion. This is a critical detoxification process that allows the females to maintain ammonia levels below lethal concentration. In this grant application, we propose to unravel the mechanisms of metabolic regulation for nitrogen waste, as well as the fluxes of C and N molecules involved in ammonia metabolism. We anticipate that the data collected by these studies will identify critical metabolic targets that have the potential to be selectively inhibited by small molecules that block the synthesis and/or excretion of nitrogen waste in mosquitoes.
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|Isoe, Jun; Scaraffia, Patricia Y (2013) Urea synthesis and excretion in Aedes aegypti mosquitoes are regulated by a unique cross-talk mechanism. PLoS One 8:e65393|