Transcriptomic evidence of a dramatic functional transition of the Malpighian tubules after a blood meal in the Asian tiger mosquito (Aedes albopictus)

In adult female mosquitoes, the renal (Malpighian) tubules play a key role in the acute processing of blood meals by excreting the excess salt and water that are ingested.  This post-prandial diuresis starts during the engorgement of blood and lasts for the next 1-2 hours.  However, once the stresses to salt and water balance are alleviated, it is unclear how the Malpighian tubules contribute to the chronic processing of blood meals, when large amounts of metabolic wastes (e.g., NH₃, heme) are generated via the digestion of hemoglobin and other blood proteins.  The goal of this study is to use a transcriptomics approach to provide insights into the putative physiological roles of Malpighian tubules in the chronic processing of blood meals.  We used RNA-Seq to sequence the cDNAs expressed in the Malpighian tubules of adult female mosquitoes (Asian tiger mosquito; Aedes albopictus) at specific time points after a blood meal (3 h, 12 h, 24 h).  Tubules from non-blood fed females were used as controls.  We detected more than 1800 transcripts that were differentially expressed in tubules from blood fed females.  A DAVID functional cluster analysis of the ~900 down-regulated transcripts suggests an apparent decrease in the diuretic capacity of the tubules within the first 24 h. A similar analysis of the ~900 up-regulated transcripts suggests an increase putative new role, a chronic detoxification and excretion of toxic NH₃ and heme metabolites derived from a blood meal within the first 24 h.  Supported by an OARDC SEEDS grant to PMP.