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Previous results showed that mRNA encoding a putative aquaporin (AQP) (GenBankaccession number AF218314) is present in the tracheolar cells associated with female Aedes aegyptiMalpighian tubules. In this study, immuno-histochemistry detected the protein,AeaAQP, also in tra-cheolar cells, suggesting its involvement in water movement in the respiratory system. When expressed in Xenopus oocytes,AeaAQP increased the osmotic water permeability from15·10 )6 to 150 ·10 )6 mÆs )1 , whichwas inhibited by mercury ions. No permeability to glycerol or other solute was observed | Eur. J. Biochem. 270 422-429 2003 FEBS 2003 doi 10.1046 j.1432-1033.2003.03389.x Mosquito Aedes aegypti aquaporin present in tracheolar cells transports water not glycerol and forms orthogonal arrays in Xenopus oocyte membranes Laurence Duchesne1 Jean-Francois Hubert1 Jean-Marc Verbavatz2 Daniel Thomas1 and Patricia V. Pietrantonio3 1UMR CNRS 6026 Interactions Cellulaires et Moléculaires Universite de Rennes I Rennes France 2Service de Biologie Cellulaire CEA Saclay France 3Department of Entomology Texas A M University College Station TX USA Previous results showed that mRNA encoding a putative aquaporin AQP GenBank accession number AF218314 is present in the tracheolar cells associated with female Aedes aegypti Malpighian tubules. In this study immunohistochemistry detected the protein AeaAQP also in tra-cheolar cells suggesting its involvement in water movement in the respiratory system. When expressed in Xenopus oocytes AeaAQP increased the osmotic water permeability from 15 X 10-6 to 150 X 10-6 m-s-1 which was inhibited by mercury ions. No permeability to glycerol or other solute was observed. AeaAQP expressed in oocytes was solubilized as a homotetramer in nondenaturing detergent as deduced from velocity centrifugation on density gradients. Phylogenetic analysis of MIP major intrinsic protein family sequences shows that AeaAQP clusters with other native orthogonal array forming proteins. Specific orthogonal arrays were detected by freeze-fracture analysis of AeaAQP oocyte membranes. We conclude that in tracheolar cells of A. aegypti AeaAQP is probably a highly water-permeable homotetrameric MIP which natively can form 2D crystals. Keywords aquaporin insect respiration Malpighian tubule tracheolar cell tracheoles. Knowledge on insect respiration is abundant in the areas of morphology of the respiratory system its adaptations and the physics of respiration 1-3 . By contrast the molecular mechanisms of tracheole ventilation are poorly understood. Early work by .
