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

The renal (Malpighian) tubules of insects play important roles in hemolymph Ca 2+ regulation. Here we provide the first investigation into how dietary Ca 2+ loads from sucrose or blood meals affect the Ca 2+ content and mRNA expression of Ca 2+ transporters in Malpighian tubules of adult female mosquitoes. Using the yellow fever mosquito Aedes aegypti we found that feeding females for 6 days ad libitum on 10% sucrose with elevated Ca 2+ concentration led to concentration-dependent increases of the Ca 2+ content in Malpighian tubules. The increases of Ca 2+ content correlated with up-regulations of mRNAs encoding intracellular Ca 2+ -ATPases ( SERCA and SPCA ), a plasma membrane Ca 2+ -ATPase ( PMCA ), and a K + -dependent Na + /Ca 2+ exchanger ( NCKX1 ). We also found that when adult females were fed blood, tubule Ca 2+ content changed dynamically over the next 72 h in a manner consistent with redistribution of tubule Ca 2+ stores to other tissues (e.g., ovaries). The changes in tubule Ca 2+ were correlated with dynamic changes in mRNA abundances of SERCA , SPCA , PMCA , and NCKX1 . Our results are the first to demonstrate that Malpighian tubules of adult female mosquitoes have a remarkable capacity to handle high dietary Ca 2+ loads, most likely through the combination of storing excess Ca 2+ 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 Ca 2+ to other tissues during the processing of blood meals.