Carbonic anhydrase in the midgut of larval Aedes aegypti: cloning, localization and inhibition.
The larval mosquito midgut exhibits one of the highest pH values known in a biological system. While the pH inside the posterior midgut and gastric caeca ranges between 7.0 and 8.0, the pH inside the anterior midgut is close to 11.0. Alkalization is likely to involve bicarbonate/carbonate ions. These ions are produced in vivo by the enzymatic action of carbonic anhydrase. The purpose of this study was to investigate the role of this enzyme in the alkalization mechanism, to establish its presence and localization in the midgut of larval Aedes aegypti and to clone and characterize its cDNA. Here, we report the physiological demonstration of the involvement of carbonic anhydrase in midgut alkalization. Histochemistry and in situ hybridization showed that the enzyme appears to be localized throughout the midgut, although preferentially in the gastric caeca and posterior regions with specific cellular heterogeneity. Furthermore, we report the cloning and localization of the first carbonic anhydrase from mosquito larval midgut. A cDNA clone from Aedes aegypti larval midgut revealed sequence homology to alpha-carbonic anhydrases from vertebrates. Bioinformatics indicates the presence of at least six carbonic anhydrases or closely related genes in the genome of another dipteran, the fruit fly Drosophila melanogaster. Molecular analyses suggest that the larval mosquito may also possess multiple forms.
Corena
Maria  Pilar
M
The Whitney Laboratory, University of Florida, Saint Augustine, FL 32080, USA.
Seron
Theresa J
TJ
Lehman
Herm K
HK
Ochrietor
Judith D
JD
Kohn
Andrea
A
Tu
Chingkuang
C
Linser
Paul J
PJ
D000330:Aedes / Q000201:enzymology*; D000595:Amino Acid Sequence; D000818:Animals; D002257:Carbonic Anhydrase Inhibitors / Q000494:pharmacology*; D002256:Carbonic Anhydrases / Q000235:genetics* / Q000378:metabolism; D004064:Digestive System / Q000201:enzymology*; D006801:Humans; D017403:In Situ Hybridization; D007814:Larva; D008969:Molecular Sequence Data; D010103:Oxygen Isotopes; D010802:Phylogeny; D010957:Plasmids; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D002257:Carbonic Anhydrase Inhibitors; D010103:Oxygen Isotopes; D002256:Carbonic Anhydrases