Aquaporins (AQP) Research Papers - Academia.edu (original) (raw)

The pathophysiology of exocrine dysfunction observed in Sjögren's syndrome (SS) is not fully understood. The purpose of this study was to investigate whether autoan-tibodies against human AQP5 are present in the sera of SS patients.... more

The pathophysiology of exocrine dysfunction observed in Sjögren's syndrome (SS) is not fully understood. The purpose of this study was to investigate whether autoan-tibodies against human AQP5 are present in the sera of SS patients. Frozen sections of mouse submandibular salivary glands, CHO cells over-expressing a human AQP5–GFP fusion protein or GFP, and MDCK cells over-expressing AQP5 were used in the indirect immunofluorescence assay to detect anti-AQP5 autoantibodies in the sera from patients with primary SS. The lysates of HEK-293 cells over-expressing the AQP5–GFP fusion protein or GFP were used for immuno-precipitation. Serum IgG from the SS patients but not from the control subjects stained acinar cells in the mouse salivary glands, the signals of which colocalized with those of AQP5-specific antibodies. Serum IgG from the SS patients also selectively stained AQP5–GFP expressed in CHO cells. However, both the control and SS sera immunoprecipitated the AQP5–GFP, suggesting that autoantibodies against AQP5 were also present in the control sera. The screening of 53 control and 112 SS samples by indirect immunofluorescence assay using the AQP5-expressing MDCK cells revealed the presence of significantly higher levels of anti-AQP5 IgG in the SS samples than in the control samples with sensitivity of 0.73 and a specificity of 0.68. Furthermore, the presence of anti-AQP5 autoantibodies was associated with low resting salivary flow in SS patients. In conclusion, anti-AQP5 autoantibodies were detected in the sera from SS patients, which could be a novel biomarker of SS and provide new insight into the pathogenesis of SS.

GP.Mur is a clinically important red blood cell (RBC) phenotype in Southeast Asia. The molecular entity of GP.Mur is glycophorin B-A-B hybrid protein that promotes band 3 expression and band 3–AQP1 interaction, and alters the organization... more

GP.Mur is a clinically important red blood cell (RBC) phenotype in Southeast Asia. The molecular entity of GP.Mur is glycophorin B-A-B hybrid protein that promotes band 3 expression and band 3–AQP1 interaction, and alters the organization of band 3 complexes with Rh/RhAG complexes. GP.Mur+ RBCs are more resistant to osmotic stress. To explore whether GP.Mur+ RBCs could be structurally more resilient, we compared deformability and osmotic fragility of fresh RBCs from 145 adults without major illness (47% GP.Mur). We also evaluated potential impacts of cellular and lipid factors on RBC deformability and osmotic resistivity. Contrary to our anticipation, these two physical properties were independent from each other based on multivariate regression analyses. GP.Mur+ RBCs were less deformable than non-GP.Mur RBCs. We also unexpectedly found 25% microcytosis in GP.Mur+ female subjects (10/40). Both microcytosis and membrane cholesterol reduced deformability, but the latter was only obser...

Membrane proteins play crucial roles in a range of biological processes. High resolution structures provide insights into the functional mechanisms of membrane proteins, but detailed biophysical characterization of membrane proteins is... more

Membrane proteins play crucial roles in a range of biological processes. High resolution structures provide insights into the functional mechanisms of membrane proteins, but detailed biophysical characterization of membrane proteins is difficult. Complementary to experimental techniques, molecular dynamics simulations is a powerful tool in providing more complete description of the dynamics and energetics of membrane proteins with high spatial-temporal resolution. In this chapter, we provide a survey of the current methods and technique issues for setting up and running simulations of membrane proteins. The recent progress in applying simulations to understanding various biophysical properties of membrane proteins is outlined.

In recent years, the recirculating aquaponics system has gained high attention and significant popularity for organic vegetables and fruits production which contributes to the sustainable aquaculture for tropical regions. This review aims... more

In recent years, the recirculating aquaponics system has gained high attention and significant popularity for organic vegetables and fruits production which contributes to the sustainable aquaculture for tropical regions. This review aims to summarize the possibility for practicing intercropping in aquaponics to produce high-quality fruits, vegetables and fish without any chemical fertilizer and minimum ecological impact for a sustainable agriculture. Although many studies have addressed about aquaponics for producing high-value crops such as tomato, cucumber, and lettuce, there is still a lack of complete information to support the development of intercropping in aquaponics and limited focus on its commercial implementation. Moreover, this study will focus first on the requirements for inserting intercropping in aquaponics and technical improvements needed to adapt as potential for sustainable food production system to increase productivity around the world, especially in countries have deficiency in water and land resources as well as soil problem like salinity and reduce environmental emissions. Secondly, the insertion of intercropping in aquaponics must be for crops with high value and for crops that can complement together such as tomato with basil and tomato with lettuce. Thirdly, in technical improvement in this study will summarize the strategies and factors that affect the intercropping in aquaponics system such as the nutrients needed for crops under intercropping aquaponics, stocking density and feeding rate which are important to know the concentration of ammonia that is produced and converted to nitrate so that the plants can uptake it. Studying the requirements for inserting and improving intercropping in aquaponics will increase our understanding of needed for new agriculture technique that contributes to the sustainable aquaponics for tropical regions.

In recent years, the recirculating aquaponics system has gained high attention and significant popularity for organic vegetables and fruits production which contributes to the sustainable aquaculture for tropical regions. This review aims... more

In recent years, the recirculating aquaponics system has gained high attention and significant popularity for organic vegetables and fruits production which contributes to the sustainable aquaculture for tropical regions. This review aims to summarize the possibility for practicing intercropping in aquaponics to produce high-quality fruits, vegetables and fish without any chemical fertilizer and minimum ecological impact for a sustainable agriculture. Although many studies have addressed about aquaponics for producing high-value crops such as tomato, cucumber, and lettuce, there is still a lack of complete information to support the development of intercropping in aquaponics and limited focus on its commercial implementation. Moreover, this study will focus first on the requirements for inserting intercropping in aquaponics and technical improvements needed to adapt as potential for sustainable food production system to increase productivity around the world, especially in countries...

Sertoli cells play a key role in the establishment of an adequate luminal environment in the seminiferous tubules of the male reproductive tract. Secretion of the seminiferous tubular fluid (STF) is vital for the normal occurrence of... more

Sertoli cells play a key role in the establishment of an adequate luminal environment in the seminiferous tubules of the male reproductive tract. Secretion of the seminiferous tubular fluid (STF) is vital for the normal occurrence of spermatogenesis and for providing a means of transport to the developing spermatozoa. However, several studies on this subject have not completely clarified the origin and composition of this fluid. Electrolyte and water are central components of STF. Sertoli cells secrete an iso-osmotic fluid with a higher content of K+ than the blood and express various membrane and water transporters (Na+/K+-ATPase; Ca2+-ATPase; V-type ATPase; Cl− channels; CFTR Cl− channels; K+ channels; L-, T- and N-type Ca2+ channels; Na+/H+ exchangers; Na+-driven HCO3−/Cl− exchangers (NDCBEs); Na+/HCO3− cotransporters (NBCes); Na+–K+–2Cl− cotransporter; Na+/Ca2+ exchanger; and aquaporins 0 and 8) involved in cellular and secretory functions. Studies with knockout mice for some of these transporters showed tubular fluid accumulation and associated infertility, revealing the relevance of these processes for the normal occurrence of spermatogenesis. Nevertheless, the role of the several membrane transporters in the establishment of STF electrolyte composition needs to be further elucidated. This review summarizes the available data on the ionic composition of STF and on the Sertoli cell membrane mechanisms responsible for ion and water movement. Deepening the knowledge on the mechanisms involved in the secretion, composition and regulation of SFT is essential and will be a major step in understanding the infertility associated with some pathological conditions.

Bile is primarily secreted in hepatocytes (i.e. the canalicular bile) and subsequently delivered to the intrahepatic bile ducts, where is modified by cholangiocytes (i.e. the ductal bile). Bile formation is the result of the coordinated... more

Bile is primarily secreted in hepatocytes (i.e. the canalicular bile) and subsequently delivered to the intrahepatic bile ducts, where is modified by cholangiocytes (i.e. the ductal bile). Bile formation is the result of the coordinated interactions of membrane-transport systems that generate the vectorial movement of solutes and osmotically driven water molecules. Hepatocytes and cholangiocytes express aquaporins, specialized membrane channel proteins that facilitate the osmotic transport of water. In this review, we provide a summary of what is known on liver AQPs and their significance in canalicular and ductal bile formation under normal and pathological conditions.

Purpose. To determine the complete primary structure, including posttranslational modifica- tions, of bovine lens major intrinsic protein (MIP) using a recently developed combination of liquid chromatography and mass spectrometry.... more

Purpose. To determine the complete primary structure, including posttranslational modifica- tions, of bovine lens major intrinsic protein (MIP) using a recently developed combination of liquid chromatography and mass spectrometry. Methods. The MIP was isolated from bovine lenses by sucrose gradient centrifugation and was cleaved widi cyanogen bromide (CNBr). A high-performance liquid chromatographic system, developed for hydrophobic protein analysis, was used

In this study we have compared the short-term effects of both NaCl and HgCl2 on aquaporins of Capsicum annuum L. plants, in order to determine whether or not they are similar. Stomatal conductance, turgor, root hydraulic conductance and... more

In this study we have compared the short-term effects of both NaCl and HgCl2 on aquaporins of Capsicum annuum L. plants, in order to determine whether or not they are similar. Stomatal conductance, turgor, root hydraulic conductance and water status were measured after 0.5, 2, 4 and 6 h of NaCl (60 mmol/L) or HgCl2 (50 μmol/L) treatment. When 60 mmol/L NaCl was added to the nutrient solution, a large decrease in stomatal conductance was observed after 2 h. However, when HgCl2 (50 μmol/L) was added, the decrease occurred after 4 h. The number of open stomata closed was always lower in plants treated with HgCl2 than in plants treated with NaCl. The water content of the Hg2+-treated plants was decreased, compared with controls and NaCl-treated. The root hydraulic conductance decreased after HgCl2 and NaCl treatment plants. Turgor of leaf epidermal cells was greatly reduced in plants treated with HgCl2, but remained constant in the NaCl treatment, compared with control plants. The fact that the stomatal conductance was reduced more rapidly after NaCl addition, followed by the stomatal closure, and that both water content and turgor did not differ from the control suggests that in NaCl-treated plants there must be a signal moving from root to shoot. Therefore, the control of plant homeostasis through a combined regulation of root and stomatal exchanges may be dependent on aquaporin regulation.

The ability of neutrophils to sense and move to sites of infection is essential for our defense against pathogens. For motility, lamellipodium extension and stabilization are prerequisites, but how cells form such membrane protrusions is... more

The ability of neutrophils to sense and move to sites of infection is essential for our defense against pathogens. For motility, lamellipodium extension and stabilization are prerequisites, but how cells form such membrane protrusions is still obscure. Using contrast-enhanced video microscopy and Transwell assays, we show that water-selective aquaporin channels regulate lamellipodium formation and neutrophil motility. Addition of anti-aquaporin-9 antibodies, HgCl(2), or tetraethyl ammonium inhibited the function(s) of the channels and blocked motility-related shape changes. On human neutrophils, aquaporin-9 preferentially localized to the cell edges, where N-formyl peptide receptors also accumulated, as assessed with fluorescence microscopy. To directly visualize water fluxes at cell edges, cells were loaded with high dilution-sensitive, self-quenching concentrations of fluorophore. In these cells, motile regions always displayed increased fluorescence compared with perinuclear regi...