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Guoli Zhou, Roger MiesfeldDepartment of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USAAbstract: Amino acids in the mosquito blood meal have two forms, protein-bound and plasma-free amino acids. To determine if the metabolic fate and flux of these two forms of blood meal amino acids are distinct, we fed mosquitoes eight [14C]-labeled amino acids, seven of which are essential for mosquitoes (leucine, valine, isoleucine, phenylalanine, lysine, arginine, histidine), and one that can be readily converted to metabolic fuel (alanine). These 14C tracer amino acids were either incorporated into an in vitro synthesized protein (protein-bound) and fed with blood to mosquitoes, or fed individually (free) with blood. In both forms, leucine had the highest relative flux with regard to synthesizing mosquito body lipid reserves, whereas histidine and arginine were the most highly excreted. We also found that protein-bound phenylalanine was incorporated at the highest rate into egg proteins, while plasma-free isoleucine was readily incorporated into egg proteins. Considering that plasma-free amino acids are rapidly absorbed and metabolized within the first eight hours post-blood meal, it is likely that the difference in egg protein incorporation reflects differential utilization of plasma-free isoleucine and phenylalanine. In order to determine if the metabolic fate of plasma-free isoleucine is affected by the origin of host blood or the number of gonotrophic cycles, we supplemented porcine and human blood with [14C]-isoleucine in the absence or presence of 200 µM unlabeled isoleucine. Our data show that host blood does not affect isoleucine incorporation into protein, and that plasma-free isoleucine incorporated into maternal proteins during the first gonotrophic cycle functions as an isoleucine reservoir for the second gonotrophic cycle.Keywords: amino acid metabolism, metabolic flux, metabolic fate, gonotrophic cycle, host preference |
