RNA-seq comparison of larval and adult malpighian tubules of Aedes aegypt, the yellow fever mosquito

The life history of Ae. aegypti presents its diuretic system with diverse challenges - during the larval and pupal life stages mosquitoes are aquatic, following adult emergence they become terrestrial.  This shifts the organism within minutes from an aquatic environment where water is readily available to a terrestrial environment where dehydration is a threat. Additionally, female mosquitoes take large blood meals which present entirely new sets of challenges to the diuretic system. 

In order to determine differences in gene expression associated with these different life stages, we performed an RNA-seq analysis of the Malpighian tubules in Ae. aegypti.  We compared transcript abundance in 4th instar larva to that of adult females, 3 days post-eclosion and analyzed the data with focus on transcripts potentially involved in diuresis. We compared our results against the model of potassium- and sodium chloride excretion in the Malpighian tubules proposed by Beyenbach (2011), which involves at least 8 ion transporters and a proton-pump.

We found 8,584 of 18,769 (45.7%) transcripts to have at least a 2.5 fold change in expression levels between the two groups.  We identified two transporter genes that are highly expressed in the adult Malpighian tubules which may play important roles in diuresis, which had not previously been part of the model. We were also able to identify candidates for hypothesized sodium and chloride channels which previously had not been recognized because they are members of large gene families. We confirmed the involvement in adult diuresis of some proteins via RNAi-mediated knockdown.