(2nd Place) Impact of blood feeding on the immunochemical expression of PMCA in Malpighian tubules of adult female Aedes aegypti

Renal (Malpighian) tubules of female Aedes aegypti contribute to hemolymph calcium (Ca²⁺) homeostasis mainly via Ca²⁺ sequestration into the intracellular compartments and Ca²⁺ secretion into the tubule lumen and/or mosquito hemolymph. Plasma membrane Ca²⁺-ATPase (PMCA), a putative Ca²⁺ extrusion mechanism, exhibited differential mRNA expression in mosquito Malpighian tubules within 72 h post blood feeding (PBF), suggesting a potential role of PMCA in the renal Ca²⁺ regulation of female mosquitoes during blood meal processing. To add further insights into how PMCA contribute to renal Ca²⁺ homeostasis in female Ae. aegypti, here we used semi-quantitative immunochemical approaches to characterize the abundance and localization of PMCA-like immunoreactivity in Ae. aegypti Malpighian tubules PBF. Western blots with an antibody against Drosophila PMCA revealed evidence for the presence of at least two PMCA-like proteins in mosquito Malpighian tubules: a 115 kDa isoform and a 109 kDa isoform. Intriguingly, the 115 kDa isoform increased in abundance PBF, while that of the 109 kDa isoform decreased. Whole mount immunohistochemistry on Malpighian tubules showed that PMCA-like immunolabeling occurred both intracellularly in principal cells and on the basolateral membrane of stellate cells. Moreover, signaling appeared strengthened in stellate cells PBF, but weakened in principal cells. Taken together, these results suggest that different PMCA isoforms might localize in stellate cells and principal cells respectively, where they may perform unique roles but collectively contribute to the renal regulation of hemolymph Ca²⁺ homeostasis in female Ae. aegypti, especially under the context of blood feeding.