Dietary calcium (Ca2+) impacts Ca2+content and molecular expression of Ca2+-transporters in Malpighian tubules of the yellow fever mosquito,Aedes aegypti

Abstract

AbstractThe renal (Malpighian) tubules of insects play important roles in hemolymph Ca2+regulation. Here we provide the first investigation into how dietary Ca2+loads from sucrose or blood meals affect the Ca2+content and mRNA expression of Ca2+transporters in Malpighian tubules of adult female mosquitoes. Using the yellow fever mosquitoAedes aegyptiwe found that feeding females for 6 daysad libitumon 10% sucrose with elevated Ca2+concentration led to concentration-dependent increases of the Ca2+content in Malpighian tubules. The increases of Ca2+content correlated with up-regulations of mRNAs encoding intracellular Ca2+-ATPases (SERCAandSPCA), a plasma membrane Ca2+-ATPase (PMCA), and a K+-dependent Na+/Ca2+exchanger (NCKX1). We also found that when adult females were fed blood, tubule Ca2+content changed dynamically over the next 72 h in a manner consistent with redistribution of tubule Ca2+stores to other tissues (e.g., ovaries). The changes in tubule Ca2+were correlated with dynamic changes in mRNA abundances ofSERCA,SPCA,PMCA, andNCKX1. Our results are the first to demonstrate that Malpighian tubules of adult female mosquitoes have a remarkable capacity to handle high dietary Ca2+loads, most likely through the combination of storing excess Ca2+within intracellular compartments and secreting it into the tubule lumen for excretion. Our results also suggest that the Malpighian tubules play key roles in supplying Ca2+to other tissues during the processing of blood meals.