Characterization of Carbonic Anhydrase 9 in the Alimentary Canal of Aedes aegypti and Its Relationship to Homologous Mosquito Carbonic Anhydrases

Abstract

In the mosquito midgut, luminal pH regulation and cellular ion transport processes are important for the digestion of food and maintenance of cellular homeostasis. pH regulation in the mosquito gut is affected by the vectorial movement of the principal ions including bicarbonate/carbonate and protons. As in all metazoans, mosquitoes employ the product of aerobic metabolism carbon dioxide in its bicarbonate/carbonate form as one of the major buffers of cellular and extracellular pH. The conversion of metabolic carbon dioxide to bicarbonate/carbonate is accomplished by a family of enzymes encoded by the carbonic anhydrase gene family. This study characterizes Aedes aegypti carbonic anhydrases using bioinformatic, molecular, and immunohistochemical methods. Our analyses show that there are fourteen Aedes aegypti carbonic anhydrase genes, two of which are expressed as splice variants. The carbonic anhydrases were classified as either integral membrane, peripheral membrane, mitochondrial, secreted, or soluble cytoplasmic proteins. Using polymerase chain reaction and Western blotting, one of the carbonic anhydrases, Aedes aegypti carbonic anhydrase 9, was analyzed and found in each life stage, male/female pupae, male/female adults, and in the female posterior midgut. Next, carbonic anhydrase 9 was analyzed in larvae and adults using confocal microscopy and was detected in the midgut regions. According to our analyses, carbonic anhydrase 9 is a soluble cytoplasmic enzyme found in the alimentary canal of larvae and adults and is expressed throughout the life cycle of the mosquito. Based on previous physiological analyses of adults and larvae, it appears AeCA9 is one of the major carbonic anhydrases involved in producing bicarbonate/carbonate which is involved in pH regulation and ion transport processes in the alimentary canal. Detailed understanding of the molecular bases of ion homeostasis in mosquitoes will provide targets for novel mosquito control strategies into the new millennium.

Larvicidal Activity of Cinnamic Acid Derivatives: Investigating Alternative Products for Aedes aegypti L. Control

“…Specifically, CA has been proposed to play an important role in bicarbonate metabolism, pH regulation and ions transportation in the alimentary canal of Ae. aegypti [ 38 ]. Thus, its inhibition is a strategy to explore for the development of larvicidal compounds.…”

The genome of the brackish-water malaria vectorAnopheles aquasalis

“…albimanus , when exposed to gradual changes in saline water, specialized non-dorsal anterior rectal (non-DAR) cells undergo changes in the localization of V-type ATPases and K+/Na+ ATPases proteins, allowing the production of super osmotic urine and disrupting the ion reabsorption system in non-DAR cells (8, 9). Other studies in mosquitoes have also suggested the importance of Carbonic Anhydrase (CA) and aquaporins to osmoregulation in saline environments (10, 12). We found that An.…”

“…Studies on the tolerance of An. albimanus to saltwater also suggest the importance of V-type ATPase, carbonic anhydrase, and K+/Na+ ATPase proteins to osmoregulation (8)(9)(10)(11)(12), and studies in other insects have shown the role of aquaporins in such process. Orthology searches suggest that An.…”

“…albimanus (8,9). Other molecular and transcriptome studies also suggest that other genes, such as aquaporin and carbonic anhydrases, in conjunction with transcription modulation, are essential for mosquito survival in hyperosmotic or hypo-osmotic environments (10)(11)(12) Besides its peculiar ecological features, recent research recognized An. aquasalis as an important model for studying the interaction with human Plasmodium and murine models such as P. yoelii nigeriensis (13)(14)(15).…”