Characterization of pH and ion regulatory proteins in larval mosquitoes

Mosquitoes have long been a major cause of human morbidity and mortality, and as a result, worldwide efforts are underway to control these disease vectors. Evidence suggests that targeting the larval stages of the mosquito lifecycle in addition to the adult stage may facilitate vector control. In order to specifically and safely target mosquito larvae using control methods, a thorough understanding of the biological systems crucial for larval survival is necessary. Here I characterize proteins that influence larvae's ability to tightly control the pH within their alimentary canal, as well as proteins involved in their ability to adapt to varying environmental conditions. Uncovering the methods of pH and ion regulation employed by larvae in both of these processes could lead to the discovery of novel targets and new and improved larvicides.;First, I report the cloning and characterization of novel carbonic anhydrase transcripts from the larval Anopheles gambiae alimentary canal. Mosquito larvae generate a highly alkaline pH in a restricted area of the alimentary canal, and carbonic anhydrase is a crucial enzyme for the generation and maintenance of this pH. Characterization of mRNA expression and protein distribution in the case of one CA, AgCA9, reveal an alternate pathway for bicarbonate/carbonate transport into the lumen of the alimentary canal, updating the current model for larval pH regulation. Additionally, RNA interference work in an An. gambiae larval cell line demonstrates that AgCA9 is a protein capable of being manipulated by RNAi and suggests that this technique can be used to silence a CA in live mosquito larvae.;Finally, antibody immunolocalization of AgCA9 reveals a novel subset of cells in the rectum of anopheline larvae. I characterize the cells of this rectum using immunohistochemistry, physiology, and pharmacology and use this data to develop a putative model of ion regulation in the anopheline rectum. This model supports my current hypothesis that anopheline larvae shift protein distribution to change the primary function of the rectum from absorption, in larvae reared in fresh water, to secretion, in larvae reared in saline water. Additionally, this work emphasizes the differences in rectal structure and protein regulation between anophelines and culicines, and suggests that these two subfamilies may be employ very different adaptive and regulatory strategies.