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1
Sone, M., A. Ohno, G. J. Albrecht, K. Thurau, and F. X. Beck. "Restoration of urine concentrating ability and accumulation of medullary osmolytes after chronic diuresis." American Journal of Physiology-Renal Physiology 269, no. 4 (October 1, 1995): F480—F490. http://dx.doi.org/10.1152/ajprenal.1995.269.4.f480.
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Restoration of urine osmolality (Uosm) and medullary osmolyte contents after chronic diuresis was studied in rats infused for 6 days with furosemide and subsequently given the vasopressin analogue, 1-desamino-8-D-arginine vasopressin (DDAVP). Papillary tip intra- and extracellular electrolyte concentrations were measured by electron microprobe analysis, tissue contents of methylamines (glycerophosphorylcholine, betaine), polyols (myo-inositol, sorbitol), and several amino acids in different kidney zones by high-performance liquid chromatography. Administering DDAVP continuously after diuresis increased Uosm from (means +/- SE) 348 +/- 8 to 1,265 +/- 127 after 1 day and 2,485 +/- 186 mosmol/kgH2O after 3 days. The sum of all osmolytes at the papillary tip rose from 309.2 +/- 28.9 to 690.9 +/- 105.8 and 1,282.8 +/- 21.0 mmol/kg protein after days 1 and 3, respectively. Although interstitial tonicity (sum of Na, Cl, and K concentrations) was increased by 116 and 223% after 1 and 3 days DDAVP, intracellular tonicity was similar in chronic diuresis and following 1 or 3 days DDAVP. Coadministration of DDAVP with betaine, myo-inositol, and choline (“osmolyte treatment”) did not accelerate the restoration of Uosm but caused significantly higher contents of osmolytes (except myo-inositol) in inner medulla and/or papilla after 3 days. In a minority of animals, restoration of Uosm and reaccumulation of medullary osmolytes were impeded in both DDAVP- and DDAVP/osmolyte-treated rats. These data indicate that, after chronic diuresis, accumulation of organic osmolytes and restoration of Uosm proceed in parallel. Capacity for transport and/or synthesis of organic osmolytes, rather than their availability, appear to limit reaccumulation on the first day of recovery. By the third day, delivery of some osmolytes or their precursors may limit the restoration of medullary osmolyte content. The failure of some rats to attain sufficient concentrating ability within this time period may be related to deficient reaccumulation of medullary osmolytes.
2
Qu, Youxing, C. L. Bolen, and D. W. Bolen. "Osmolyte-driven contraction of a random coil protein." Proceedings of the National Academy of Sciences 95, no. 16 (August 4, 1998): 9268–73. http://dx.doi.org/10.1073/pnas.95.16.9268.
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The Stokes radius characteristics of reduced and carboxamidated ribonuclease A (RCAM RNase) were determined for transfer of this “random coil” protein from water to 1 M concentrations of the naturally occurring protecting osmolytes trimethylamineN-oxide, sarcosine, sucrose, and proline and the nonprotecting osmolyte urea. The denatured ensemble of RCAM RNase expands in urea and contracts in protecting osmolytes to extents proportional to the transfer Gibbs energy of the protein from water to osmolyte. This proportionality suggests that the sum of the transfer Gibbs energies of individual parts of the protein is responsible for the dimensional changes in the denatured ensemble. The dominant term in the transfer Gibbs energy of RCAM RNase from water to protecting osmolytes is the unfavorable interaction of the osmolyte with the peptide backbone, whereas the favorable interaction of urea with the backbone dominates in RCAM RNase transfer to urea. The side chains collectively favor transfer to the osmolytes, with some protecting osmolytes solubilizing hydrophobic side chains as well as urea does, a result suggesting there is nothing special about the ability of urea to solubilize hydrophobic groups. Protecting osmolytes stabilize proteins by raising the chemical potential of the denatured ensemble, and the uniform thermodynamic force acting on the peptide backbone causes the collateral effect of contracting the denatured ensemble. The contraction decreases the conformational entropy of the denatured state while increasing the density of hydrophobic groups, two effects that also contribute to the ability of protecting osmolytes to force proteins to fold.
3
Goude, Renan, St�phanie Renaud, Sylvie Bonnassie, Th�ophile Bernard, and Carlos Blanco. "Glutamine, Glutamate, and α-Glucosylglycerate Are the Major Osmotic Solutes Accumulated by Erwinia chrysanthemi Strain 3937." Applied and Environmental Microbiology 70, no. 11 (November 2004): 6535–41. http://dx.doi.org/10.1128/aem.70.11.6535-6541.2004.
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ABSTRACT Erwinia chrysanthemi is a phytopathogenic soil enterobacterium closely related to Escherichia coli. Both species respond to hyperosmotic pressure and to external added osmoprotectants in a similar way. Unexpectedly, the pools of endogenous osmolytes show different compositions. Instead of the commonly accumulated glutamate and trehalose, E. chrysanthemi strain 3937 promotes the accumulation of glutamine and α-glucosylglycerate, which is a new osmolyte for enterobacteria, together with glutamine. The amounts of the three osmolytes increased with medium osmolarity and were reduced when betaine was provided in the growth medium. Both glutamine and glutamate showed a high rate of turnover, whereas glucosylglycerate stayed stable. In addition, the balance between the osmolytes depended on the osmolality of the medium. Glucosylglycerate and glutamate were the major intracellular compounds in low salt concentrations, whereas glutamine predominated at higher concentrations. Interestingly, the ammonium content of the medium also influenced the pool of osmolytes. During bacterial growth with 1 mM ammonium in stressing conditions, more glucosylglycerate accumulated by far than the other organic solutes. Glucosylglycerate synthesis has been described in some halophilic archaea and bacteria but not as a dominant osmolyte, and its role as an osmolyte in Erwinia chrysanthemi 3937 shows that nonhalophilic bacteria can also use ionic osmolytes.
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Kossowska, Dorota, Kyungwon Kwak, and Minhaeng Cho. "Do Osmolytes Impact the Structure and Dynamics of Myoglobin?" Molecules 23, no. 12 (December 3, 2018): 3189. http://dx.doi.org/10.3390/molecules23123189.
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Osmolytes are small organic compounds that can affect the stability of proteins in living cells. The mechanism of osmolytes’ protective effects on protein structure and dynamics has not been fully explained, but in general, two possibilities have been suggested and examined: a direct interaction of osmolytes with proteins (water replacement hypothesis), and an indirect interaction (vitrification hypothesis). Here, to investigate these two possible mechanisms, we studied myoglobin-osmolyte systems using FTIR, UV-vis, CD, and femtosecond IR pump-probe spectroscopy. Interestingly, noticeable changes are observed in both the lifetime of the CO stretch of CO-bound myoglobin and the spectra of UV-vis, CD, and FTIR upon addition of the osmolytes. In addition, the temperature-dependent CD studies reveal that the protein’s thermal stability depends on molecular structure, hydrogen-bonding ability, and size of osmolytes. We anticipate that the present experimental results provide important clues about the complicated and intricate mechanism of osmolyte effects on protein structure and dynamics in a crowded cellular environment.
5
Bagnasco, S. M., M. H. Montrose, and J. S. Handler. "Role of calcium in organic osmolyte efflux when MDCK cells are shifted from hypertonic to isotonic medium." American Journal of Physiology-Cell Physiology 264, no. 5 (May 1, 1993): C1165—C1170. http://dx.doi.org/10.1152/ajpcell.1993.264.5.c1165.
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Madin-Darby canine kidney (MDCK) cells accumulate the nonperturbing osmolytes myo-inositol and betaine when grown in hypertonic medium. When returned to isotonic conditions, there is a transient basolateral efflux of these osmolytes, contributing to regulatory volume decrease. Using fura-2 fluorescence, we estimated intracellular calcium concentrations after switching MDCK cells from 500 to 300 mosM medium. Cell calcium increased 565 +/- 93 nM within 5 min. Lowering extracellular calcium inhibited the increase in cell calcium and osmolyte efflux when cells were shifted from 500 to 300 mosM medium. The calcium channel blockers lanthanum and nifedipine also inhibited osmolyte efflux after the shift from 500 to 300 mosM. In the absence of change in medium tonicity, increasing cell calcium by exposure to 1 microM ionomycin did not alter osmolyte efflux. As in PAP-HT25 cells, the cytochrome P-450 inhibitors ketoconazole and SKF-525A inhibited the efflux of both osmolytes caused by a reduction in osmolarity. Thus an early rise in cell calcium that is dependent on extra-cellular calcium and a pathway blocked by inhibitors of cytochrome P-450 oxidase are critical in regulation of osmolyte efflux when MDCK cells are shifted from hypertonic to isotonic medium.
6
Tiwari, Mrityunjay K., and Rajesh K. Murarka. "Interaction strength of osmolytes with the anion of a salt-bridge determines its stability." Physical Chemistry Chemical Physics 23, no. 9 (2021): 5527–39. http://dx.doi.org/10.1039/d0cp05378c.
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The salt-bridge (SB) interaction energy and the energy of interaction between osmolyte and SB anion are anti-linearly correlated, suggesting that by merely knowing osmolyte⋯acetate interaction, one might predict the influence of osmolytes on a SB.
7
Nakanishi, T., O. Uyama, H. Nakahama, Y. Takamitsu, and M. Sugita. "Determinants of relative amounts of medullary organic osmolytes: effects of NaCl and urea differ." American Journal of Physiology-Renal Physiology 264, no. 3 (March 1, 1993): F472—F479. http://dx.doi.org/10.1152/ajprenal.1993.264.3.f472.
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Sorbitol, inositol, betaine, taurine, and glycerophosphorylcholine (GPC) are organic osmolytes that accumulate in the renal inner medulla during antidiuresis. In the cultured cell model, high medium sodium increases all the cell osmolytes and high medium urea increases cell GPC and inositol. It has been difficult, however, to discriminate between the effects of sodium and urea on organic osmolytes in water-deprived animals. To determine the nature of the in vivo responses of osmolyte accumulation induced by extracellular sodium or urea, we measured the medullary organic osmolytes and tested the degree of their linear correlation with urine and tissue parameters in control, dehydrated, salt-loaded, and urea-loaded rats. All of the osmolytes except myo-inositol increased in salt-loaded rats. Betaine and sorbitol contents in dehydrated rats were less than in salt-loaded rats, but other osmolytes increased significantly. Conversely, in urea-loaded rats, only GPC increased significantly, whereas either no change occurred for other osmolytes or sometimes betaine and sorbitol levels decreased. These data suggest that high sodium increases all of the osmolytes except myoinositol, whereas high urea increases only GPC and may decrease the renal medullary contents of betaine and sorbitol. We also demonstrated, using linear regression analysis, that urea and electrolyte in urine as well as tissue correlate well with each osmolyte measured.
8
Warskulat, Ulrich, Stefanie Brookmann, Andrea Reinen, and Dieter Häussinger. "Ultraviolet B radiation induces cell shrinkage and increases osmolyte transporter mRNA expression and osmolyte uptake in HaCaT keratinocytes." Biological Chemistry 388, no. 12 (December 1, 2007): 1345–52. http://dx.doi.org/10.1515/bc.2007.140.
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Abstract We have previously shown that compatible organic osmolytes, such as betaine, myo-inositol and taurine, are part of the stress response of normal human keratinocytes (NHKs) to ultraviolet B (UVB) radiation. In this regard, we tested human HaCaT keratinocytes as a surrogate cell line for NHK. HaCaT cells osmo-dependently express mRNA specific for transport proteins for betaine (BGT-1), myo-inositol (SMIT) and taurine (TAUT). Compared to normoosmotic (305 mosmol/l) controls, which strongly constitutively expressed BGT-1 mRNA, strong induction of SMIT and TAUT mRNA as well as low induction of BGT-1 mRNA expression was observed between 3 and 9 h after hyperosmotic exposure (405 mosmol/l). This expression correlated with an increased osmolyte uptake. Conversely, hypoosmotic (205 mosmol/l) stimulation led to a significant efflux of osmolytes. Exposure to UVB (290–315 nm) radiation induced cell shrinkage which was followed by an upregulation of osmolyte transporter mRNA levels and osmolyte uptake. These results demonstrate that human HaCaT keratinocytes possess an osmolyte strategy including UVB-induced cell shrinkage and following increased osmolyte uptake. However, several differences in osmolyte transporter expression and uptake were noted between NHK and HaCaT cells, indicating that the use of HaCaT cells as a surrogate cell line for NHK has limitations.
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Heilig, C. W., M. E. Stromski, and S. R. Gullans. "Methylamine and polyol responses to salt loading in renal inner medulla." American Journal of Physiology-Renal Physiology 257, no. 6 (December 1, 1989): F1117—F1123. http://dx.doi.org/10.1152/ajprenal.1989.257.6.f1117.
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Methylamines and polyhydric alcohols (polyols) are major organic osmolytes of the mammalian renal inner medulla and have generally been noted to change in parallel with urine osmolality. In the present study, responses of inner medullary methylamines and polyols to 5 days of salt loading were investigated. Salt loading increased plasma sodium concentration and induced a saline diuresis that resulted in a significantly lower urine osmolality (Uosmol) in salt-loaded rats (1,246 mosmol) compared with controls (2,147 mosmol). Analysis of inner medullary organic osmolytes using 1H-NMR spectroscopy and biochemical assays indicated no significant change in total methylamines, total polyols, or total osmolytes with salt loading. However, there were marked changes in individual organic osmolytes. Renal inner medullary glycerophosphorylcholine (GPC) was 41% lower in salt-loaded rats, and was the only organic osmolyte that changed in parallel with Uosmol, which was 42% lower in this group. In contrast, glycine betaine (betaine) and sorbitol contents were elevated by 286% and 33%, respectively, with salt loading, and myo-inositol (inositol) was unchanged. These findings indicate selective renal inner medullary osmolyte responses to salt loading with only GPC varying directly with changes in urine osmolality.
10
Schmolke, M., A. Bornemann, and W. G. Guder. "Site-specific regulation of organic osmolytes along the rat nephron." American Journal of Physiology-Renal Physiology 271, no. 3 (September 1, 1996): F645—F652. http://dx.doi.org/10.1152/ajprenal.1996.271.3.f645.
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The regulation of organic osmolytes was investigated in acute furosemide and chronic lithium diuresis along the nephron and in urinary bladder of rats. Sorbitol, myo-inositol, glycerophosphorylcholine, and betaine were measured enzymatically or by high performance liquid chromatography in homogenates and bioluminometrically in microdissected tubules. In untreated rats, all osmolytes except myo-inositol increased along the corticopapillary axis. An efflux of all osmolytes (-50%) was observed in homogenates of outer and inner medulla after acute furosemide diuresis (15 min, urinary osmolality = 329 mosmol/kgH2O) and for both polyols in microdissected tubules (30 min). In urinary bladder, only low concentrations of myo-inositol were found not to be affected by furosemide treatment. Chronic lithium treatment (7 days; urinary osmolality = 385 mosmol/kgH2O) decreased inner medullary but not outer medullary osmolyte concentrations. The results confirm a site-specific organic osmolyte pattern along the rat nephron, which is rapidly changed in a segment-specific way by different mechanisms of diuresis. The bladder epithelium does not accumulate organic osmolytes because no "osmotic gap" exists across the basolateral membrane. The osmotic difference across the apical membrane is maintained by the apical tightness of these cells.
11
Moran, J., D. Miranda, C. Pena-Segura, and H. Pasantes-Morales. "Volume regulation in NIH/3T3 cells not expressing P-glycoprotein. II. Chloride and amino acid fluxes." American Journal of Physiology-Cell Physiology 272, no. 6 (June 1, 1997): C1804—C1809. http://dx.doi.org/10.1152/ajpcell.1997.272.6.c1804.
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The osmolyte function of amino acids and Cl in native NIH/3T3 cells not expressing the P-glycoprotein was examined by investigating the free amino acid concentration and the swelling-activated efflux of [3H]taurine, as representative of amino acids, and of 125I, as a tracer for Cl. Taurine and 125I efflux was activated by 20 and 30% hyposmotic solutions. At 50% hyposmotic solutions, the osmolyte pool was essentially depleted. The Cl channel blockers 5-nitro-2-(3-phenylpropyl-amino)benzoic acid, 1,9-dideoxyforskolin, dipyridamole, and niflumic acid inhibited the release of the two osmolytes by 80-95%. 4,4'-Diisothiocyanostilbene-2,2'-disulfonic acid (400 microM) decreased the efflux of taurine 80% without affecting that of 125I. Linolenic and arachidonic acids (5-20 microM) showed a concentration-dependent inhibitory effect on taurine and 125I fluxes. Omission of Ca decreased osmolyte fluxes by 16%. Verapamil inhibited the osmolyte release only at 500 microM. Nimodipine at 25 and 50 microM decreased the release of [3H]taurine and 125I by approximately 60 and 80%, respectively, but this effect was independent of the presence of extracellular Ca. These results indicate that amino acids and Cl function as osmolytes during regulatory volume decrease in native NIH/ 3T3 cells.
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Hamdane, Djemel, Christophe Velours, David Cornu, Magali Nicaise, Murielle Lombard, and Marc Fontecave. "A chemical chaperone induces inhomogeneous conformational changes in flexible proteins." Physical Chemistry Chemical Physics 18, no. 30 (2016): 20410–21. http://dx.doi.org/10.1039/c6cp03635j.
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Organic osmolytes are major cellular compounds that favor protein's compaction and stabilization of the native state. Here, we have examined the chaperone effect of the naturally occurring trimethylamine N-oxide (TMAO) osmolyte on a flexible protein.
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Moeckel, Gilbert W., Li Zhang, Xiwu Chen, Michele Rossini, Roy Zent, and Ambra Pozzi. "Role of integrin α1β1 in the regulation of renal medullary osmolyte concentration." American Journal of Physiology-Renal Physiology 290, no. 1 (January 2006): F223—F231. http://dx.doi.org/10.1152/ajprenal.00371.2004.
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The mechanism by which cells sense extracellular tonicity and trigger the accumulation of protective organic osmolytes is poorly understood. It has been proposed that changes in cell volume following alteration of extracellular toncity are important initiators of signaling events that lead to osmolyte accumulation. Because the extracellular matrix receptors integrins are linked to the cytoskeleton and can transduce signals that alter cell behavior, we investigated the role of these receptors in the modulation of osmolyte accumulation in the kidney medulla under different osmotic conditions. We show that integrin α1-null mice have impaired ability to accumulate organic osmolytes in the inner medulla due to altered signaling and decreased induction of osmolyte transporters or aldose reductase gene transcription. Utilizing inner medullary collecting duct cells, we demonstrate that the lack of integrin α1β1 results in an impaired ability to induce the tonicity enhancer-binding protein TonEBP under hypertonic conditions. Furthermore, under the same conditions, integrin α1-null cells show prolonged ERK1/2 phosphorylation and decreased inositol uptake compared with control cells. The reduction of inositol uptake is significantly reversed by treatment with the MEK inhibitor PD-98059. Finally, integrin α1-null mice develop morphological changes of early tubular necrosis and increased apoptosis of renal medullary cells following dehydration. Together, these results show that integrin α1β1 is an important mediator of the compatible osmolyte response in the medulla of the mammalian kidney.
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Kwon, E. D., J. A. Dooley, K. Y. Jung, P. M. Andrews, A. Garcia-Perez, and M. B. Burg. "Organic osmolyte distribution and levels in the mammalian urinary bladder in diuresis and antidiuresis." American Journal of Physiology-Renal Physiology 271, no. 1 (July 1, 1996): F230—F233. http://dx.doi.org/10.1152/ajprenal.1996.271.1.f230.
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Inositol, sorbitol, glycerophosphocholine (GPC), and betaine are organic osmolytes that are accumulated by renal medullary cells in response to hyperosmotic stress. Previous screening studies, using nuclear magnetic resonance spectroscopy, have shown some of these same compounds to be present in extracts of whole urinary bladder from rabbits and rats. In the present study, we used high-performance liquid chromatography to quantify levels of these compounds in the separated epithelium and muscle of bladders taken from normal rabbits as well as diuretic and thirsted rats. We find that 1) high concentrations of organic osmolytes, namely inositol, GPC, and sorbitol, are present in urinary bladder; 2) levels of these osmolytes in the bladder epithelium are higher than in the muscle; 3) increased urinary osmolality due to antidiuresis is associated with a 2.4-fold increase in total osmolyte levels in rat bladder epithelium and a lesser (1.5-fold) increase in the muscle, compared with corresponding levels in tissues from diuretic animals; and 4) these increases in total osmolyte amounts in the epithelium are due to increased levels of GPC, sorbitol, and perhaps inositol (P = 0.07), whereas only GPC increases in the bladder muscle.
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Verma, R., N. Singh, and P. Chaudhuri (Chattopadhyay). "Nanoparticles Mediated Protein Stability in Comparison with Osmolytes: in vivo Approach." Asian Journal of Chemistry 33, no. 6 (2021): 1433–38. http://dx.doi.org/10.14233/ajchem.2021.23219.
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The native three-dimensional structure of protein is quite unstable under critical destabilizing conditions. In order to enhance the stability and activity for a proper folded environment of a protein, many stabilizing materials are added such as nanoparticles and osmolytes to an unfolded state of protein. Osmolytes are the important group of molecules which are engaged by the cell as an adaption in the severe conditions. In this communication, a comparative in vivo study is reported for imparting the status of stability and folding ability of zebrafish dihydrofolate reductase (zDHFR) protein with gold nanoparticles and various osmolytes (glycerol, glucose and betain). Present observations revealed that the interaction of gold nanoparticles (AuNPs) with bacteria at the cellular level helps in maintaining the stability of protein more effectively than osmolytes which could be used for many biological and pharmacological approaches although glycerol as an osmolyte also stabilizes the protein at a significant level.
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Arns, Loana, Vitor Schuabb, Shari Meichsner, Melanie Berghaus, and Roland Winter. "The Effect of Natural Osmolyte Mixtures on the Temperature-Pressure Stability of the Protein RNase A." Zeitschrift für Physikalische Chemie 232, no. 5-6 (May 24, 2018): 615–34. http://dx.doi.org/10.1515/zpch-2017-1039.
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Abstract In biological cells, osmolytes appear as complex mixtures with variable compositions, depending on the particular environmental conditions of the organism. Based on various spectroscopic, thermodynamic and small-angle scattering data, we explored the effect of two different natural osmolyte mixtures, which are found in shallow-water and deep-sea shrimps, on the temperature and pressure stability of a typical monomeric protein, RNase A. Both natural osmolyte mixtures stabilize the protein against thermal and pressure denaturation. This effect seems to be mainly caused by the major osmolyte components of the osmolyte mixtures, i.e. by glycine and trimethylamine-N-oxide (TMAO), respectively. A minor compaction of the structure, in particular in the unfolded state, seems to be largely due to TMAO. Differences in thermodynamic properties observed for glycine and TMAO, and hence also for the two osmolyte mixtures, are most likely due to different solvation properties and interactions with the protein. Different from TMAO, glycine seems to interact with the amino acid side chains and/or the backbone of the protein, thus competing with hydration water and leading to a less hydrated protein surface.
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Huang, Xi, Yanmei Huang, Raj Chinnappan, Claire Bocchini, Michael C. Gustin, and Michael Stern. "The Drosophila inebriated-Encoded Neurotransmitter/Osmolyte Transporter: Dual Roles in the Control of Neuronal Excitability and the Osmotic Stress Response." Genetics 160, no. 2 (February 1, 2002): 561–69. http://dx.doi.org/10.1093/genetics/160.2.561.
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Abstract Water reabsorption by organs such as the mammalian kidney and insect Malpighian tubule/hindgut requires a region of hypertonicity within the organ. To balance the high extracellular osmolarity, cells within these regions accumulate small organic molecules called osmolytes. These osmolytes can accumulate to a high level without toxic effects on cellular processes. Here we provide evidence consistent with the possibility that the two protein isoforms encoded by the inebriated (ine) gene, which are members of the Na+/Cl−-dependent neurotransmitter/osmolyte transporter family, perform osmolyte transport within the Malpighian tubule and hindgut. We show that ine mutants lacking both isoforms are hypersensitive to osmotic stress, which we assayed by maintaining flies on media containing NaCl, KCl, or sorbitol, and that this hypersensitivity is completely rescued by high-level ectopic expression of the ine-RB isoform. We provide evidence that this hypersensitivity represents a role for ine that is distinct from the increased neuronal excitability phenotype of ine mutants. Finally, we show that each ine genotype exhibits a “threshold” [NaCl]: long-term maintenance on NaCl-containing media above, but not below, the threshold causes lethality. Furthermore, this threshold value increases with the amount of ine activity. These data suggest that ine mutations confer osmotic stress sensitivity by preventing osmolyte accumulation within the Malpighian tubule and hindgut.
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Kunte, Hans Jörg. "Osmoregulation in Bacteria: Compatible Solute Accumulation and Osmosensing." Environmental Chemistry 3, no. 2 (2006): 94. http://dx.doi.org/10.1071/en06016.
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Environmental Context.Bacteria and Archaea have developed two basic mechanisms to cope with osmotic stress. The ‘salt-in-cytoplasm mechanism’ involves adjusting the salt concentration in the cytoplasm according to the environmental osmolarity and the ‘organic-osmolyte mechanism’ involves accumulating uncharged, highly water-soluble organic compounds in order to maintain an osmotic equilibrium with the surrounding medium. This highlight gives an overview of the osmoadaptation of prokaryotes employing the organic-osmolyte strategy and introduces a model explaining the fine-tuning of osmoregulatory osmolyte synthesis. Abstract.Bacteria and Archaea have developed two basic mechanisms to cope with osmotic stress, the salt-in-cytoplasm mechanism, and the organic-osmolyte mechanism. Organic osmolytes or so-called compatible solutes can be accumulated in molar concentration in the cytoplasm and allow for the adaptation of bacterial cells to varying salt concentrations. The biosynthetic pathways of compatible solutes and different compatible solute transport systems are described. A model for osmoregulatory compatible solute accumulation is introduced.
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Sharma, Anket, Babar Shahzad, Vinod Kumar, Sukhmeen Kaur Kohli, Gagan Preet Singh Sidhu, Aditi Shreeya Bali, Neha Handa, Dhriti Kapoor, Renu Bhardwaj, and Bingsong Zheng. "Phytohormones Regulate Accumulation of Osmolytes Under Abiotic Stress." Biomolecules 9, no. 7 (July 17, 2019): 285. http://dx.doi.org/10.3390/biom9070285.
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Plants face a variety of abiotic stresses, which generate reactive oxygen species (ROS), and ultimately obstruct normal growth and development of plants. To prevent cellular damage caused by oxidative stress, plants accumulate certain compatible solutes known as osmolytes to safeguard the cellular machinery. The most common osmolytes that play crucial role in osmoregulation are proline, glycine-betaine, polyamines, and sugars. These compounds stabilize the osmotic differences between surroundings of cell and the cytosol. Besides, they also protect the plant cells from oxidative stress by inhibiting the production of harmful ROS like hydroxyl ions, superoxide ions, hydrogen peroxide, and other free radicals. The accumulation of osmolytes is further modulated by phytohormones like abscisic acid, brassinosteroids, cytokinins, ethylene, jasmonates, and salicylic acid. It is thus important to understand the mechanisms regulating the phytohormone-mediated accumulation of osmolytes in plants during abiotic stresses. In this review, we have discussed the underlying mechanisms of phytohormone-regulated osmolyte accumulation along with their various functions in plants under stress conditions.
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Karsten, U., KD Barrow, O. Nixdorf, and RJ King. "The Compability with Enzyme Activity of Unusual Organic Osmolytes from Mangrove Red Algae." Functional Plant Biology 23, no. 5 (1996): 577. http://dx.doi.org/10.1071/pp9960577.
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The effects of organic osmolytes synthesised and accumulated by red algae from mangrove habitats were investigated on the in vitro activities of two major enzymes, one of the citric acid cycle (malate dehydrogenase, MDH) and one of the oxidative pentose phosphate pathway (glucose-6- phosphate dehydrogenase, G6PDH). These enzymes were extracted from the mangrove algae Bostrychia tenella, Caloglossa leprieurii, Catenella nipae and Stictosiphonia hookeri. In each case, activity of the enzymes was inhibited with increasing NaCl concentrations up to 600 mM . In contrast, equimolar concentrations of mannitol (the major osmolyte in C. leprieurii), sorbitol (the major osmolyte in B. Tenella and S. hookeri) and a heteroside mixture (of which floridoside is the major osmolyte in C. nipae) did not inhibit enzyme function. Dulcitol, the second most important organic osmolyte in B. tenella, exerted no negative effect at its maximum solubility of 180 rnM on the salt-sensitive MDH. These data are all consistent with the proposed function of these organic compounds as compatible solutes.
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Kumar, Raj, Jenna F. DuMond, Shagufta H. Khan, E. Brad Thompson, Yi He, Maurice B. Burg, and Joan D. Ferraris. "NFAT5, which protects against hypertonicity, is activated by that stress via structuring of its intrinsically disordered domain." Proceedings of the National Academy of Sciences 117, no. 33 (August 3, 2020): 20292–97. http://dx.doi.org/10.1073/pnas.1911680117.
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Nuclear Factor of Activated T cells 5 (NFAT5) is a transcription factor (TF) that mediates protection from adverse effects of hypertonicity by increasing transcription of genes, including those that lead to cellular accumulation of protective organic osmolytes. NFAT5 has three intrinsically ordered (ID) activation domains (ADs). Using the NFAT5 N-terminal domain (NTD), which contains AD1, as a model, we demonstrate by biophysical methods that the NTD senses osmolytes and hypertonicity, resulting in stabilization of its ID regions. In the presence of sufficient NaCl or osmolytes, trehalose and sorbitol, the NFAT5 NTD undergoes a disorder-to-order shift, adopting higher average secondary and tertiary structure. Thus, NFAT5 is activated by the stress that it protects against. In its salt and/or osmolyte-induced more ordered conformation, the NTD interacts with several proteins, including HMGI-C, which is known to protect against apoptosis. These findings raise the possibility that the increased intracellular ionic strength and elevated osmolytes caused by hypertonicity activate and stabilize NFAT5.
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Sanchez-Olea, R., M. Morales, O. Garcia, and H. Pasantes-Morales. "Cl channel blockers inhibit the volume-activated efflux of Cl and taurine in cultured neurons." American Journal of Physiology-Cell Physiology 270, no. 6 (June 1, 1996): C1703—C1708. http://dx.doi.org/10.1152/ajpcell.1996.270.6.c1703.
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The effects of the Cl channel blockers 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB), 1,9-dideoxyforskolin (DDF), dipyridamole, and niflumic acid and of the polyunsaturated fatty acids arachidonic, linolenic, and linoleic acids on regulatory volume decrease (RVD) and associated 125I and [3H]taurine fluxes in cultured rat cerebellar granule neurons were examined. Dose-response curves of NPPB, DDF, and dipyridamole showed 20-100% inhibition of RVD and osmolyte fluxes. Niflumic acid was less potent, requiring 150-600 microM to show effects of this magnitude. The polyunsaturated fatty acids (5-20 microM) inhibited 80-90% RVD and osmolyte fluxes, with arachidonic acid exhibiting the most potent effect. The volume-associated taurine efflux was somewhat higher in younger neurons, but the pharmacological sensitivity was essentially the same in immature and mature cells. The effects of all tested drugs on 125I and [3H]taurine fluxes were remarkably similar, indicating a close pharmacological sensitivity of the transport mechanism for the two osmolytes. This is in line with the suggestion of a common pathway for the volume-associated release of Cl and amino acids functioning as osmolytes.
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Honarbakhsh, Shirin, Mojtaba Zaghari, and Mahmood Shivazad. "Investigation of feeding betaine as an osmoprotectant in broiler chicks." Proceedings of the British Society of Animal Science 2007 (April 2007): 242. http://dx.doi.org/10.1017/s1752756200021451.
Full textAbstract:
Trimethylglycine has two primary metabolic roles: it is a methyl group donor and an osmolyte that assists in cellular water homeostasis. Tissues that rely on zwitterionic betaine as an osmolyte include the intestines, kidney, liver, brain and leukocytes. Osmolytes are particularly important in situations in which cellular dehydration is present because these compounds help minimize water loss despite a prevailing osmotic gradient. Thus, water balance homeostasis is an important factor for cells exposed to a variety of osmotic conditions (Klasing et al., 2002). For example, the osmotic pressure of the intestinal contents varies during the process of digestion. The osmotic difference between the intestinal epithelium and the luminal fluid is likely to necessitate means to control the osmotic pressure inside the intestinal epithelial cells. Betaine, as an organic compatible osmolyte, is one of the most likely candidates for the task.
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Peterson, D. P., K. M. Murphy, R. Ursino, K. Streeter, and P. H. Yancey. "Effects of dietary protein and salt on rat renal osmolytes: covariation in urea and GPC contents." American Journal of Physiology-Renal Physiology 263, no. 4 (October 1, 1992): F594—F600. http://dx.doi.org/10.1152/ajprenal.1992.263.4.f594.
Full textAbstract:
Renal medullary cells contain high levels of (glycine) betaine, glycerophosphorylcholine (GPC), myo-inositol, and sorbitol. Two functions of these have been proposed: 1) that they are compatible osmolytes which regulate cell volume (against high external NaCl) without inhibiting proteins and 2) that methylamines (GPC and betaine) are counteracting osmolytes which stabilize proteins against perturbation from high renal urea. As a test of the latter, osmolyte contents in kidney medullas were measured in rats subjected to three types of dietary manipulation: 1) diets with protein and NaCl contents varied oppositely, 2) diets with a constant low NaCl and varied protein content, and 3) a low-calorie diet. With low-protein and low-calorie diets, only renal contents of urea, GPC, and inositol decreased; betaine and sorbitol contents increased such that contents of total nonurea organic osmolytes remained constant. With high-protein diets, only renal contents of sodium, urea, and GPC increased, with the latter giving total organic osmolytes a consistent correlation to sodium. Across all diets, the only consistent (linear) correlations were 1) between urea and GPC contents, supporting previous suggestions that GPC is the major counteractant to urea, and 2) between total organic osmolytes and sodium (but not urea) contents, as predicted by the compatible osmolytes hypothesis.
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Yancey, P. H., and M. B. Burg. "Distribution of major organic osmolytes in rabbit kidneys in diuresis and antidiuresis." American Journal of Physiology-Renal Physiology 257, no. 4 (October 1, 1989): F602—F607. http://dx.doi.org/10.1152/ajprenal.1989.257.4.f602.
Full textAbstract:
Sorbitol, glycerophosphorylcholine (GPC), inositol, and betaine are organic osmolytes that accumulate in renal medullary cells. Two roles have been proposed for them: 1) that all four are “compatible osmolytes” that help regulate cell volume without disturbing function, and 2) that the methylamines (GPC and betaine) are “counteracting osmolytes,” i.e., stabilizers that offset the perturbing effects of the high urea concentration. To test these hypotheses we have measured the osmolyte gradients in diuresis and antidiuresis in rabbit kidneys cut in 7 sections along the corticopapillary axis. In both antidiuresis and diuresis, inositol was highest in the outer medulla and decreased toward the tip of the inner medulla. In antidiuresis, contents of sodium, urea, sorbitol, GPC, and betaine increased monotonically toward the tip of the inner medulla. All osmolytes were significantly lower in diuresis compared with antidiuresis in two or more kidney sections. Urea, GPC, and sorbitol had the greatest differences between the two states. The sum of the four (mainly intracellular) compatible osmolytes showed a strong linear correlation with Na (presumably mostly extracellular), with a similar slope in both states, consistent with the compatible osmolytes hypothesis. Considering the osmolytes individually, only two linear correlations were highly significant and had similar slopes in both diuresis and antidiuresis: betaine with Na and GPC with urea. The latter is consistent with the counteracting osmolytes hypothesis, suggesting that GPC is the main agent stabilizing against urea in the renal medulla.
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Liao, Yi-Ting, Anthony C. Manson, Michael R. DeLyser, William G. Noid, and Paul S. Cremer. "TrimethylamineN-oxide stabilizes proteins via a distinct mechanism compared with betaine and glycine." Proceedings of the National Academy of Sciences 114, no. 10 (February 22, 2017): 2479–84. http://dx.doi.org/10.1073/pnas.1614609114.
Full textAbstract:
We report experimental and computational studies investigating the effects of three osmolytes, trimethylamineN-oxide (TMAO), betaine, and glycine, on the hydrophobic collapse of an elastin-like polypeptide (ELP). All three osmolytes stabilize collapsed conformations of the ELP and reduce the lower critical solution temperature (LSCT) linearly with osmolyte concentration. As expected from conventional preferential solvation arguments, betaine and glycine both increase the surface tension at the air–water interface. TMAO, however, reduces the surface tension. Atomically detailed molecular dynamics (MD) simulations suggest that TMAO also slightly accumulates at the polymer–water interface, whereas glycine and betaine are strongly depleted. To investigate alternative mechanisms for osmolyte effects, we performed FTIR experiments that characterized the impact of each cosolvent on the bulk water structure. These experiments showed that TMAO red-shifts the OH stretch of the IR spectrum via a mechanism that was very sensitive to the protonation state of the NO moiety. Glycine also caused a red shift in the OH stretch region, whereas betaine minimally impacted this region. Thus, the effects of osmolytes on the OH spectrum appear uncorrelated with their effects upon hydrophobic collapse. Similarly, MD simulations suggested that TMAO disrupts the water structure to the least extent, whereas glycine exerts the greatest influence on the water structure. These results suggest that TMAO stabilizes collapsed conformations via a mechanism that is distinct from glycine and betaine. In particular, we propose that TMAO stabilizes proteins by acting as a surfactant for the heterogeneous surfaces of folded proteins.
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Jackson, P. S., R. Morrison, and K. Strange. "The volume-sensitive organic osmolyte-anion channel VSOAC is regulated by nonhydrolytic ATP binding." American Journal of Physiology-Cell Physiology 267, no. 5 (November 1, 1994): C1203—C1209. http://dx.doi.org/10.1152/ajpcell.1994.267.5.c1203.
Full textAbstract:
Efflux of intracellular organic osmolytes to the external medium is a ubiquitous response to cell swelling. Accumulating evidence indicates that volume regulatory loss of structurally unrelated organic osmolytes from cells is mediated by a relatively nonselective volume-sensitive anion channel. In C6 cells, we have termed this channel VSOAC for volume-sensitive organic osmolyte-anion channel. Swelling-induced activation of VSOAC required the presence of ATP or nonhydrolyzable ATP analogues [adenosine 5'-O-(3-thiotriphosphate), adenylylmethyl-enediphosphonate (AMP-PCP), or 5'-adenylylimidodiphosphate] in the patch pipette. Sustained activation of VSOAC also required ATP. Channel rundown was observed when cellular ATP levels were lowered by intracellular dialysis with the patch pipette solution. Rundown was prevented by the ATP analogue AMP-PCP. Passive swelling-induced myo-[3H]inositol and [3H]taurine efflux was blocked by metabolic inhibitors that decreased cellular ATP levels. Titration of cellular ATP levels with azide demonstrated that the apparent dissociation constant (Kd) for ATP of both myo-inositol and taurine efflux was approximately 1.7 mM. The high Kd for ATP indicates that cellular metabolic state plays an important role in modulating organic osmolyte loss. Regulation of VSOAC activity by ATP prevents depletion of metabolically expensive organic osmolytes when cellular energy production is reduced. In addition, ATP-dependent regulation provides essential feedback to minimize the loss of energy-producing carbon sources such as pyruvate, short-chain fatty acids, ketone bodies, and amino acids, which readily permeate this channel.
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Sterns, R. H., J. Baer, S. Ebersol, D. Thomas, J. W. Lohr, and D. E. Kamm. "Organic osmolytes in acute hyponatremia." American Journal of Physiology-Renal Physiology 264, no. 5 (May 1, 1993): F833—F836. http://dx.doi.org/10.1152/ajprenal.1993.264.5.f833.
Full textAbstract:
The defense of brain volume during hyponatremia cannot be explained by the losses of brain sodium and potassium. We have examined the brain losses of organic osmolytes in rats after 24 h of severe hyponatremia induced by the administration of vasopressin and 5% dextrose in water. Normonatremic controls and animals with intermediate plasma sodium concentration ([Na]) were produced in vasopressin-treated animals by the administration of isocaloric gavages containing varying amounts of NaCl and free water. The animals were killed at 24 h by decapitation, and one brain hemisphere was quickly frozen in liquid nitrogen for organic osmolyte determinations. When compared with controls (plasma [Na] = 139 +/- 1.5 mM), hyponatremic animals (plasma [Na] = 96 +/- 1 mM) had significantly reduced brain contents for sodium, potassium, chloride, glutamate, myo-inositol, N-acetylaspartate, aspartate, creatine, taurine, gamma-aminobutyric acid, and phosphoethanolamine. Plasma [Na] was highly correlated (P < 0.001) with the brain contents for sodium, potassium, and organic osmolytes. Whereas the observed increase in brain water during hyponatremia was only 4.8%, by calculation, brain swelling without brain organic osmolyte losses would have been 11%, an amount that jeopardizes survival.
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Stevens, M. J., D. N. Henry, T. P. Thomas, P. D. Killen, and D. A. Greene. "Aldose reductase gene expression and osmotic dysregulation in cultured human retinal pigment epithelial cells." American Journal of Physiology-Endocrinology and Metabolism 265, no. 3 (September 1, 1993): E428—E438. http://dx.doi.org/10.1152/ajpendo.1993.265.3.e428.
Full textAbstract:
A "compatible osmolyte hypothesis" proposes that intracellular nonionic organic osmolytes such as sorbitol, myo-inositol, taurine, betaine, and glycerophosphorylcholine respond coordinately to changes in external osmolality, thereby maintaining the intracellular ionic milieu. Osmoregulation may be the primary physiological function of aldose reductase, which catalyzes the conversion of glucose to sorbitol. Glucose-induced sorbitol accumulation in isosmotic hyperglycemic states is associated with compensatory depletion of myo-inositol and taurine. Because such depletion may predispose to chronic diabetic complications, the relationship between osmolyte shifts and aldose reductase gene expression was studied in two human retinal pigment epithelial cell lines, one exhibiting osmoregulated and the other high basal aldose reductase gene expression. High basal expression of the aldose reductase gene was associated with rapid sorbitol accumulation and myo-inositol depletion in response to hyperglycemic (20 mM) concentrations of glucose. Myo-inositol and sorbitol behaved as compensating intracellular osmolytes by accumulating markedly in response to hyperosmolality (300 mM mannitol). Thus the pattern of response of myo-inositol to hyperglycemic and hyperosmotic levels of glucose and mannitol was related to the degree of basal aldose reductase gene expression, which may therefore influence the development of diabetic complications.
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Kim, Sung-Hye, Yong-Bin Yan, and Hai-Meng Zhou. "Role of osmolytes as chemical chaperones during the refolding of aminoacylase." Biochemistry and Cell Biology 84, no. 1 (February 1, 2006): 30–38. http://dx.doi.org/10.1139/o05-148.
Full textAbstract:
The refolding and reactivation of aminoacylase is particularly difficult because of serious off-pathway aggregation. The effects of 4 osmolytes — dimethylsulphoxide, glycerol, proline, and sucrose — on the refolding and reactivation of guanidine-denaturated aminoacylase were studied by measuring aggregation, enzyme activity, intrinsic fluorescence spectra, 1-anilino-8-naphthalenesulfonate (ANS) fluorescence spectra, and circular dishroism (CD) spectra. The results show that all the osmolytes not only inhibit aggregation but also recover the activity of aminoacylase during refolding in a concentration-dependent manner. In particularly, a 40% glycerol concentration and a 1.5 mol/L sucrose concentration almost completely suppressed the aminoacylase aggregation. The enzyme activity measurements revealed that the influence of glycerol is more significant than that of any other osmolyte. The intrinsic fluorescence results showed that glycerol, proline, and sucrose stabilized the aminoacylase conformation effectively, with glycerol being the most effective. All 4 kinds of osmolytes reduced the exposure of the hydrophobic surface, indicating that osmolytes facilitate the formation of protein hydrophobic collapse. The CD results indicate that glycerol and sucrose facilitate the return of aminoacylase to its native secondary structure. The results of this study suggest that the ability of the various osmolytes to facilitate the refolding and renaturation of aminoacylase is not the same. A survey of the results in the literature, as well as those presented here, suggests that although the protective effect of osmolytes on protein activity and structure is equal for different osmolytes, the ability of osmolytes to facilitate the refolding of various proteins differs from case to case. In all cases, glycerol was found to be the best stabilizer and a folding aid.Key words: protein aggregation, aminoacylase, chaperone, osmolytes, protein refolding.
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Angelidis, Apostolos S., and Gary M. Smith. "Three Transporters Mediate Uptake of Glycine Betaine and Carnitine by Listeria monocytogenes in Response to Hyperosmotic Stress." Applied and Environmental Microbiology 69, no. 2 (February 2003): 1013–22. http://dx.doi.org/10.1128/aem.69.2.1013-1022.2003.
Full textAbstract:
ABSTRACT The uptake and accumulation of the potent osmolytes glycine betaine and carnitine enable the food-borne pathogen Listeria monocytogenes to proliferate in environments of elevated osmotic stress, often rendering salt-based food preservation inadequate. To date, three osmolyte transport systems are known to operate in L. monocytogenes: glycine betaine porter I (BetL), glycine betaine porter II (Gbu), and a carnitine transporter OpuC. We investigated the specificity of each transporter towards each osmolyte by creating mutant derivatives of L. monocytogenes 10403S that possess each of the transporters in isolation. Kinetic and steady-state osmolyte accumulation data together with growth rate experiments demonstrated that osmotically activated glycine betaine transport is readily and effectively mediated by Gbu and BetL and to a lesser extent by OpuC. Osmotically stimulated carnitine transport was demonstrated for OpuC and Gbu regardless of the nature of stressing salt. BetL can mediate weak carnitine uptake in response to NaCl stress but not KCl stress. No other transporter in L. monocytogenes 10403S appears to be involved in osmotically stimulated transport of either osmolyte, since a triple mutant strain yielded neither transport nor accumulation of glycine betaine or carnitine and could not be rescued by either osmolyte when grown under elevated osmotic stress.
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Ferraris, J. D., M. B. Burg, C. K. Williams, E. M. Peters, and A. Garcia-Perez. "Betaine transporter cDNA cloning and effect of osmolytes on its mRNA induction." American Journal of Physiology-Cell Physiology 270, no. 2 (February 1, 1996): C650—C654. http://dx.doi.org/10.1152/ajpcell.1996.270.2.c650.
Full textAbstract:
Cells generally adapt to long-term hyperosmolality by accumulating compatible organic osmolytes, thereby helping to normalize both volume and intracellular inorganic ion concentration. When organic osmolytes are accumulated, as in renal inner medullary cells, it is the sum of their concentrations that is theoretically important. In effect, when one organic osmolyte rises, the others generally fall to maintain their sum approximately constant. The present study addresses the mechanism controlling betaine accumulation. Hypertonicity induces accumulation of betaine, sorbitol, inositol, and other organic osmolytes in PAP-HT25 cells, a line derived from rabbit renal papilla. Hypertonicity increases the betaine transporter expression in these cells. To obtain a specific probe for betaine transporter mRNA, we cloned from PAP-HT25 cells a cDNA that encodes the full protein. We then examined the effect of betaine, sorbitol, and inositol on betaine transporter mRNA abundance. Increased accumulation of any of these three organic osmolytes reduces betaine transporter mRNA. We previously observed similar results for aldose reductase, the enzyme responsible for osmotically regulated sorbitol accumulation. We conclude that the accumulation of organic osmolytes regulates betaine transporter gene expression. Because the aldose reductase gene is controlled in a similar fashion, we surmise that the two genes share a common signal for induction.
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Wirthensohn, G., S. Lefrank, M. Schmolke, and W. G. Guder. "Regulation of organic osmolyte concentrations in tubules from rat renal inner medulla." American Journal of Physiology-Renal Physiology 256, no. 1 (January 1, 1989): F128—F135. http://dx.doi.org/10.1152/ajprenal.1989.256.1.f128.
Full textAbstract:
Glycerophosphorylcholine, inositol, and sorbitol were measured in rat kidney homogenates and tubules from inner medulla and papilla by enzymatic spectrophotometric techniques. Organic osmolytes exhibited their highest concentrations in the papillary tip. In contrast to glycerophosphorylcholine and sorbitol, inositol was of similar high concentrations in inner and outer medulla. Freshly prepared inner medullary tubules maintained tissue osmolyte concentrations under control, antidiuretic, and furosemide diuretic conditions. When tubules were incubated in vitro over 90 min, tubular organic osmolyte concentrations decreased as a function of extracellular NaCl, but not urea concentrations. Organic osmolyte disappearance from cells was quantitatively recovered from the medium. In contrast, medium lactate dehydrogenase activity did not rise in parallel and tubular ATP remained constant. Glucose up to a concentration of 200 mM increased tubule and medium sorbitol. The results obtained indicate that glycerophosphorylcholine, sorbitol, and inositol rapidly adapt their intracellular concentrations to extracellular NaCl osmolality by a change in tubular plasma membrane permeability. In addition sorbitol levels are regulated by the extracellular glucose concentration.
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Lien, Y. H., M. M. Pacelli, and E. J. Braun. "Characterization of organic osmolytes in avian renal medulla: a nonurea osmotic gradient system." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 264, no. 6 (June 1, 1993): R1045—R1049. http://dx.doi.org/10.1152/ajpregu.1993.264.6.r1045.
Full textAbstract:
We measured the organic osmolytes present in the renal cortex and medullary cones of adult female domestic fowl before and after 48 h of water deprivation. Urine osmolality increased from 198 +/- 82 to 569 +/- 42 mosmol/kgH2O after water deprivation. In water-deprived birds, the major organic osmolytes, myoinositol, betaine, and taurine, in the medullary cones increased by 40, 100, and 24%, respectively, compared with control birds. No sorbitol was detected, and glycerophosphorylcholine (GPC) content was not affected by water deprivation. In the renal cortex, only betaine content increased significantly (4.8 +/- 0.6 vs. 3.1 +/- 0.3 mmol/kg wet wt) after water deprivation. In this study, we demonstrated that birds, like mammals, accumulate organic osmolytes in response to the increased interstitial osmolality that occurs during antidiuresis. Because urea is nearly absent in the avian medullary interstitium, our observation that GPC is not osmoregulated in the avian kidney supports the idea that GPC is the “counteracting osmolyte” for urea in the mammalian kidney. Furthermore, the organic osmolytes present in avian medullary cones are remarkably similar to those of the mammalian outer medulla. This similarity may be relevant to the morphological analogy of the two regions.
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Gullans, S. R., J. D. Blumenfeld, J. A. Balschi, M. Kaleta, R. M. Brenner, C. W. Heilig, and S. C. Hebert. "Accumulation of major organic osmolytes in rat renal inner medulla in dehydration." American Journal of Physiology-Renal Physiology 255, no. 4 (October 1, 1988): F626—F634. http://dx.doi.org/10.1152/ajprenal.1988.255.4.f626.
Full textAbstract:
Osmotically active organic solutes, osmolytes, exist at high concentrations in the renal inner medulla; however, their modulation during antidiuresis remains largely undefined. Renal osmolyte levels were measured by nuclear magnetic resonance spectroscopy and biochemical assays in perchloric acid extracts from normal and dehydrated (3 days) rats. Dehydration increased urine osmolality from 1,503 to 3,748 mosmol/kg and inner medullary urea content from 2,036 to 4,405 nmol/mg protein. In addition, inner medullary trimethylamines [glycerophosphorylcholine (GPC) and betaine] and polyhydric alcohols (inositol and sorbitol) significantly increased by 95 and 78%, respectively. Ninhydrin-positive substances (amino acids), although abundant, were unchanged. Renal cortex also contained GPC, betaine, and inositol but only inositol increased with dehydration. Analysis of correlations among inner medullary osmolytes showed that only GPC was consistently elevated by dehydration and was not directly correlated with the other osmolytes. In contrast, betaine and inositol contents were linearly related to each other and both tended to rise only when sorbitol content was unchanged. In conclusion, the major osmolytes in the rat renal inner medulla can increase during antidiuresis but they are regulated in a complex manner.
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Panuszko, Aneta, Maciej Pieloszczyk, Anna Kuffel, Karol Jacek, Karol A. Biernacki, Sebastian Demkowicz, Janusz Stangret, and Piotr Bruździak. "Hydration of Simple Model Peptides in Aqueous Osmolyte Solutions." International Journal of Molecular Sciences 22, no. 17 (August 28, 2021): 9350. http://dx.doi.org/10.3390/ijms22179350.
Full textAbstract:
The biology and chemistry of proteins and peptides are inextricably linked with water as the solvent. The reason for the high stability of some proteins or uncontrolled aggregation of others may be hidden in the properties of their hydration water. In this study, we investigated the effect of stabilizing osmolyte–TMAO (trimethylamine N-oxide) and destabilizing osmolyte–urea on hydration shells of two short peptides, NAGMA (N-acetyl-glycine-methylamide) and diglycine, by means of FTIR spectroscopy and molecular dynamics simulations. We isolated the spectroscopic share of water molecules that are simultaneously under the influence of peptide and osmolyte and determined the structural and energetic properties of these water molecules. Our experimental and computational results revealed that the changes in the structure of water around peptides, caused by the presence of stabilizing or destabilizing osmolyte, are significantly different for both NAGMA and diglycine. The main factor determining the influence of osmolytes on peptides is the structural-energetic similarity of their hydration spheres. We showed that the chosen peptides can serve as models for various fragments of the protein surface: NAGMA for the protein backbone and diglycine for the protein surface with polar side chains.
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Nakanishi, T., R. S. Balaban, and M. B. Burg. "Survey of osmolytes in renal cell lines." American Journal of Physiology-Cell Physiology 255, no. 2 (August 1, 1988): C181—C191. http://dx.doi.org/10.1152/ajpcell.1988.255.2.c181.
Full textAbstract:
In renal medullas during antidiuresis, the extracellular fluid is hyperosmotic because of high concentrations of NaCl and urea. Under those conditions, the cells contain high concentrations of organic osmolytes, namely sorbitol, myo-inositol, glycerophosphorylcholine (GPC), and betaine to balance the extracellular hyperosmolality. These organic osmolytes increase cell osmolality without perturbing the intracellular milieu in ways that would degrade the function of cellular macromolecules. The present study surveyed a number of cell lines for the ability to survive in media with high concentrations of NaCl and/or urea and for the accumulation of organic osmolytes. Of the renal cell lines tested, MDCK, GRB-MAL1, and A6 cells proliferated in hyperosmotic media, but medullary interstitial cells LLC-PK1 and LLC-PK3 did not proliferate, nor did nonrenal HTC-BH cells, MDCK, LLC-PK1, and LLC-PK3 cells contained higher concentrations of myo-inositol, GPC, and betaine when cultured in media containing high NaCl (with or without high urea) and much lower or undetectable levels of these osmolytes when grown in isosmotic media. Sorbitol, and to a lesser extent myo-inositol, were elevated in GRB-MAL1 cells in media hyperosmotic with NaCl but not in isosmotic media. There was less accumulation of organic osmolytes when only urea was added to increase osmolality. Thus the same osmolytes were accumulated by one or another cell line in vitro as were previously found in renal medullas. These cell lines provide models for studying osmolyte accumulation.
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Fox, M. A., J. P. White, A. H. F. Hosie, E. M. Lodwig, and P. S. Poole. "Osmotic Upshift Transiently Inhibits Uptake via ABC Transporters in Gram-Negative Bacteria." Journal of Bacteriology 188, no. 14 (July 15, 2006): 5304–7. http://dx.doi.org/10.1128/jb.00262-06.
Full textAbstract:
ABSTRACT ATP-binding cassette transporters from several rhizobia and Salmonella enterica serovar Typhimurium, but not secondarily coupled systems, were inhibited by high concentrations (100 to 500 mM) of various osmolytes, an effect reversed by the removal of the osmolyte. ABC systems were also inactivated in isolated pea bacteroids, probably due to the obligatory use of high-osmolarity isolation media. Measurement of nutrient cycling in isolated pea bacteroids is impeded by this effect.
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Wemekamp-Kamphuis, Henrike H., Roy D. Sleator, Jeroen A. Wouters, Colin Hill, and Tjakko Abee. "Molecular and Physiological Analysis of the Role of Osmolyte Transporters BetL, Gbu, and OpuC in Growth of Listeria monocytogenes at Low Temperatures." Applied and Environmental Microbiology 70, no. 5 (May 2004): 2912–18. http://dx.doi.org/10.1128/aem.70.5.2912-2918.2004.
Full textAbstract:
ABSTRACT Listeria monocytogenes is a ubiquitous food-borne pathogen found widely distributed in nature as well as an undesirable contaminant in a variety of fresh and processed foods. This ubiquity can be at least partly explained by the ability of the organism to grow at high osmolarity and reduced temperatures, a consequence of its ability to accumulate osmo- and cryoprotective compounds termed osmolytes. Single and multiple deletions of the known osmolyte transporters BetL, Gbu, and OpuC significantly reduce growth at low temperatures. During growth in brain heart infusion broth at 7°C, Gbu and OpuC had a more pronounced role in cryoprotection than did BetL. However, upon the addition of betaine to defined medium, the hierarchy of transporter importance shifted to Gbu > BetL > OpuC. Upon the addition of carnitine, only OpuC appeared to play a role in cryoprotection. Measurements of the accumulated osmolytes showed that betaine is preferred over carnitine, while in the absence of a functional Gbu, carnitine was accumulated to higher levels than betaine was at 7°C. Transcriptional analysis of the genes encoding BetL, Gbu, and OpuC revealed that each transporter is induced to different degrees upon cold shock of L. monocytogenes LO28. Additionally, despite being transcriptionally up-regulated upon cold shock, a putative fourth osmolyte transporter, OpuB (identified by bioinformatic analysis and encoded by lmo1421 and lmo1422), showed no significant contribution to listerial chill tolerance. Growth of the quadruple mutant LO28ΔBCGB (ΔbetL ΔopuC Δgbu ΔopuB) was comparable to the that of the triple mutant LO28ΔBCGsoe (ΔbetL ΔopuC Δgbu) at low temperatures. Here, we conclude that betaine and carnitine transport upon low-temperature exposure is mediated via three osmolyte transporters, BetL, Gbu, and OpuC.
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Nakanishi, T., F. Nishihara, A. Yamauchi, S. Yamamoto, M. Sugita, and Y. Takamitsu. "NaCl and/or urea infusion fails to increase renal inner medullary myo-inositol in protein-deprived rats." American Journal of Physiology-Renal Physiology 271, no. 6 (December 1, 1996): F1255—F1263. http://dx.doi.org/10.1152/ajprenal.1996.271.6.f1255.
Full textAbstract:
As we recently demonstrated that in potassium depletion a decrease in inner medullary organic osmolytes might precede and cause a renal concentrating defect, we hypothesized that in the protein deprivation the same mechanism may occur. To clarify the relationship between renal medullary organic osmolytes and urine concentration defects during protein deprivation, we examined the effect of protein malnutrition on organic osmolyte content after water deprivation or sodium and/or urea infusion. Water deprivation did not restore urine urea and osmolality or tissue sodium and urea in protein-deprived rats to control levels. NaCl infusion only increased urinary and medullary Na. Urea infusion increased medullary urea but not urine urea. NaCl plus urea infusion increased only urinary sodium and urea. Regardless of the protocols of hyperosmolality used, protein deprivation significantly decreased the medullary contents of myo-inositol and taurine and the level of sodium-dependent myo-inositol transporter mRNA. We conclude that factors other than NaCl and urea but associated with protein feeding are responsible for the decreased accumulation of organic osmolytes.
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Cowin, Gary J., Stuart Crozier, Zoltan H. Endre, I. Anne Leditschke, and Ian M. Brereton. "Cortical and medullary betaine-GPC modulated by osmolality independently of oxygen in the intact kidney." American Journal of Physiology-Renal Physiology 277, no. 3 (September 1, 1999): F338—F346. http://dx.doi.org/10.1152/ajprenal.1999.277.3.f338.
Full textAbstract:
Renal osmolyte concentrations are reduced during reflow following ischemia. Osmolyte decreases may follow oxygen depletion or loss of extracellular osmolality in the medulla. Image-guided volume-localized magnetic resonance (MR) microspectroscopy was used to monitor regional osmolytes during hyposmotic shock and hypoxia in the intact rat kidney. Alternate spectra were acquired from 24-μl voxels in cortex and medulla of the isolated perfused kidney. There was a progressive decrease in the combined betaine-glycerophosphorylcholine (GPC) peak intensity of 21% in cortex and 35% in medulla of normoxic kidneys between 60 and 160 min after commencing perfusion. Hypoxia had no significant effect on the betaine-GPC peak intensity in cortex or medulla, despite a dramatic reduction in tubular sodium, potassium, and water reabsorption. The results suggest that cortical and medullary intracellular osmolyte concentrations depend on osmotically regulated channels that are insensitive to oxygen and dissociated from the oxygen-dependent parameters of renal function, the fractional excretion of sodium, the fractional excretion of potassium, and urine-to-plasma inulin concentration ratio.
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Bedford, Jennifer J., John P. Leader, Rena Jing, Logan J. Walker, Janet D. Klein, Jeff M. Sands, and Robert J. Walker. "Amiloride restores renal medullary osmolytes in lithium-induced nephrogenic diabetes insipidus." American Journal of Physiology-Renal Physiology 294, no. 4 (April 2008): F812—F820. http://dx.doi.org/10.1152/ajprenal.00554.2007.
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In lithium-induced nephrogenic diabetes insipidus (NDI), alterations in renal medullary osmolyte concentrations have been assumed but never investigated. Amiloride can modify lithium-induced NDI, but the impact of amiloride in lithium-induced NDI on renal medullary osmolytes, aquaporins, and urea transporters is unknown and is the basis of this study. Rats fed lithium (60 mmol/kg dry food) over 4 wk developed NDI. Urine osmolality fell to 287 ± 19 mosmol/kgH2O (controls 1,211 ± 90 mosmol/kgH2O). Organic osmolytes in the renal medulla showed significant decreases compared with controls [inositol 221 ± 35 to 85 ± 10 mmol/kg protein; sorbitol 35 ± 9 to 3 ± 1 mmol/kg protein; glycerophosphorylcholine (GPC) 352 ± 80 to 91 ± 20 mmol/kg protein; and glycine betaine 69 ± 11 to 38 ± 38 mmol/kg protein]. Medullary urea content fell from 2,868 ± 624 to 480 ± 117 mmol/kg protein. Concurrent administration of amiloride (0.2 mmol/l) in the drinking water restored urine osmolality (1,132 ± 154 mosmol/kgH2O), and reduced urine volume. Medullary osmolyte content were restored to control values (inositol, 232 ± 12; sorbitol 32 ± 6; GPC, 244 ± 26; glycine betaine, 84 ± 5 mmol/kg protein). Medullary urea rose to 2,122 ± 305 mmol/kg protein. Reduced AQP2, AQP3, and urea transporter (UT-A1) expression was significantly reversed following amiloride therapy. Data presented here provide further understanding of how amiloride may substantially restore the lithium-induced impaired renal concentrating mechanism.
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Eun, Changsun. "Osmosis-Driven Water Transport through a Nanochannel: A Molecular Dynamics Simulation Study." International Journal of Molecular Sciences 21, no. 21 (October 28, 2020): 8030. http://dx.doi.org/10.3390/ijms21218030.
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In this work, we study a chemical method to transfer water molecules from a nanoscale compartment to another initially empty compartment through a nanochannel. Without any external force, water molecules do not spontaneously move to the empty compartment because of the energy barrier for breaking water hydrogen bonds in the transport process and the attraction between water molecules and the compartment walls. To overcome the energy barrier, we put osmolytes into the empty compartment, and to remove the attraction, we weaken the compartment-water interaction. This allows water molecules to spontaneously move to the empty compartment. We find that the initiation and time-transient behavior of water transport depend on the properties of the osmolytes specified by their number and the strength of their interaction with water. Interestingly, when osmolytes strongly interact with water molecules, transport immediately starts and continues until all water molecules are transferred to the initially empty compartment. However, when the osmolyte interaction strength is intermediate, transport initiates stochastically, depending on the number of osmolytes. Surprisingly, because of strong water-water interactions, osmosis-driven water transport through a nanochannel is similar to pulling a string at a constant speed. Our study helps us understand what minimal conditions are needed for complete transfer of water molecules to another compartment through a nanochannel, which may be of general concern in many fields involving molecular transfer.
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Andriyanto, Mochlisin, and Miftahul Huda Fendiyanto. "PENGGUNAAN SENYAWA OSMOLIT DAN ALKALIN PADA PENYADAPAN TANAMAN KARET (Hevea brasiliensis)." Jurnal Agro Estate 3, no. 2 (December 19, 2019): 110–20. http://dx.doi.org/10.47199/jae.v3i2.101.
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Stimulants are one of the common ways to increase yield in rubber plants. Recent, the stimulant that is widely used in rubber tapping is ethephon. Ethephon material can prolong the flow of latex so that yield increases. The combination of osmolyte and alkaline compounds is expected to be an alternative stimulant. Therefore, this study aimed to examine the use of osmolytes and alkaline in rubber plants. This research was conducted at the Experimental Design of the Sungei Putih Estate Research, Deli Serdang, North Sumatra in May-September 2016 with PB 260 clones planting year 2010 with a tapping system S/2 D3 Ga1.0 6 / y (m) in panel B0-2. The experimental design used was a Randomized Complete Block Design (RCBD) with 28 combinations of treatments. The observation parameters in this study were yield (g/p/s), girth (cm) before treatment application and yield (g/p/s) and yield (kg/ha/year) after treatment application. The observations showed that the addition of stimulants with osmolyte and alkaline compounds had a significant effect yield on rubber (g/p/s) in the first tapping slices. The 5% osmolyte and 10% alkaline compounds have yield rubber which is comparable to the application of stimulants made from ethephon in the first tapping slices. Application of 5% osmolyte and 10% alkaline compounds can be used as an alternative stimulant in rubber plants.
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Pliego-Marín, Lina, Javier López-Baltazar, and Edilberto Aragón-Robles. "Características físicas, nutricionales y capacidad germinativa de frijol criollo bajo estrés hídrico." Revista Mexicana de Ciencias Agrícolas, no. 6 (June 5, 2018): 1197–209. http://dx.doi.org/10.29312/remexca.v0i6.1283.
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El género Phaseolus se encuentra ampliamente distribuido en el país, en una variedad de condiciones edafoclimáticas, esto ha permitido que los agricultores del estado de Oaxaca, dada su orografía seleccionen materiales que se adapten a sus particulares condiciones. El presente trabajo se realizó en el Instituto Tecnológico del Valle de Oaxaca (ITVO), con la finalidad de evaluar colectas de semillas de frijoles criollos (Phaseolus vulgaris y Phaseolus lunatus) procedentes de los Valles Centrales de Oaxaca en cuanto a sus características físicas, nutrimentales y capacidad de germinación bajo condiciones de estrés hídrico, generado por la adición de osmolitos en el medio de germinación. Se pudo observar una variación biológica en cuanto a características físicas relacionadas con tamaño, color y peso. Los resultados indican que en relación a su composición nutricional estas colectas presentan contenidos de proteínas, grasas y fibra cruda en porcentajes similares a los reportados en otros estudios. La capacidad germinativa varió entre las colectas aun en condiciones normales (control), el valor más bajo lo presentó la colecta frijolón (52.5%), mientras que las colectas negro delgado, blanco delgado, negro grueso y colorado tuvieron el porcentaje de germinación mas alto en condiciones limitantes de agua. El PEG fue el osmolito que más redujo la capacidad germinativa de las semillas, y en el caso de sacarosa se observó que ésta favoreció el porcentaje de germinación con respecto al resto de los osmolitos utilizados.
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Wettstein, Matthias, Thorsten Peters-Regehr, Ralf Kubitz, Richard Fischer, Claudia Holneicher, Irmhild Mönnighoff, and Dieter Häussinger. "Release of osmolytes induced by phagocytosis and hormones in rat liver." American Journal of Physiology-Gastrointestinal and Liver Physiology 278, no. 2 (February 1, 2000): G227—G233. http://dx.doi.org/10.1152/ajpgi.2000.278.2.g227.
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Betaine, taurine, and inositol participate as osmolytes in liver cell volume homeostasis and interfere with cell function. In this study we investigated whether osmolytes are also released from the intact liver independent of osmolarity changes. In the perfused rat liver, phagocytosis of carbon particles led to a four- to fivefold stimulation of taurine efflux into the effluent perfusate above basal release rates. This taurine release was inhibited by 70–80% by the anion exchange inhibitor DIDS or by pretreatment of the rats with gadolinium chloride. Administration of vasopressin, cAMP, extracellular ATP, and glucagon also increased release of betaine and/or taurine, whereas insulin, extracellular UTP, and adenosine were without effect. In isolated liver cells, it was shown that parenchymal cells and sinusoidal endothelial cells, but not Kupffer cells and hepatic stellate cells, release osmolytes upon hormone stimulation. This may be caused by a lack of hormone receptor expression in these cells, because single-cell fluorescence measurements revealed an increase of intracellular calcium concentration in response to vasopressin and glucagon in parenchymal cells and sinusoidal endothelial cells but not in Kupffer cells and hepatic stellate cells. The data show that Kupffer cells release osmolytes during phagocytosis via DIDS-sensitive anion channels. This mechanism may be used to compensate for the increase in cell volume induced by the ingestion of phagocytosable material. The physiological significance of hormone-induced osmolyte release remains to be evaluated.
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Gardner, K. D., R. H. Glew, A. P. Evan, J. A. McAteer, and J. Bernstein. "Why renal cysts grow." American Journal of Physiology-Renal Physiology 266, no. 3 (March 1, 1994): F353—F359. http://dx.doi.org/10.1152/ajprenal.1994.266.3.f353.
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The growth of renal cysts leads to morbidity, contributes to mortality, and is a lesson in applied physiology. The fact that chemical, electrical, osmotic, and hydrostatic driving forces determine cyst volumes is inferred from observations that cyst fluids vary in their concentrations of osmotically active substances. Most have concentrations of sodium-based salts that are lower and nonsodium-based salts that are higher than those present in normal plasma. Nonsodium solutes include osmolytes that normally are present in higher concentrations inside of cells, including potassium, amino acids, and so-called idiogenic osmoles. The basic process of cyst growth therefore involves 1) the osmotic equilibration of water across cysts walls that have variable permeability characteristics and 2) the replacement of sodium salts with other osmotically active solutes in cyst fluids. Cyst volume is governed by the amounts and kinds of osmolytes that enter and become entrapped in lumina. Proliferation and necrosis of mural cells are events that are fundamental to the growth of renal cysts.
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Warepam, Marina, and Laishram Rajendrakumar Singh. "Osmolyte mixtures have different effects than individual osmolytes on protein folding and functional activity." Archives of Biochemistry and Biophysics 573 (May 2015): 77–83. http://dx.doi.org/10.1016/j.abb.2015.03.017.
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Nakanishi, T., A. Yamauchi, H. Nakahama, Y. Yamamura, Y. Yamada, Y. Orita, Y. Fujiwara, N. Uyeda, Y. Takamitsu, and M. Sugita. "Organic osmolytes in rat renal inner medulla are modulated by vasopressin V1 and/or V2 antagonists." American Journal of Physiology-Renal Physiology 267, no. 1 (July 1, 1994): F146—F152. http://dx.doi.org/10.1152/ajprenal.1994.267.1.f146.
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For the purpose of clarifying the role of vasopressin V1 and V2 receptors in osmolyte accumulation, we determined the effects on the inner medullary osmolyte content of the administration of orally active vasopressin V1 and/or V2 receptor antagonists OPC-21268 (i.e., 1-(1-[4-(3-acetylaminopropoxy)benzoyl]-4-piperidyl)- 3,4-dihydro-2(1H)-quinolinone) and OPC-31260 (i.e., 5-dimethylamino-1-[4-(2-methylbenzoylamino)benzoyl]-2,3,4,5-tet rah ydro-1H- benzazepine] under a condition of maximal urine concentration achieved by water deprivation for 4 days. Taurine content increased significantly with the use of the V2 antagonist, irrespective of the use of the V1 antagonist. Inner medullary betaine content decreased with the administration of the V1 antagonist, irrespective of the administration of V2 antagonist. The administration of either the V1 or V2 antagonist alone did not affect sorbitol content, aldose reductase activity, or aldose reductase mRNA abundance in renal inner medulla. However, the combined administration of the V1 and V2 antagonists decreased all of these significantly. Myo-inositol content was not affected by the administration of the V1 or V2 antagonists. Glycerophosphorylcholine content was decreased with the use of the V2 antagonist, irrespective of the use of the V1 antagonist, and this effect paralleled urine osmolality. In conclusion, the individual organic osmolytes responded differently to the antagonists of vasopressin V1 and/or V2 receptors. The mechanisms linked to vasopressin V1 and/or V2 receptors appeared to modulate the accumulation of some organic osmolytes in the inner medulla. Aldose reductase mRNA abundance and sorbitol accumulation in the inner medulla appeared to be mediated through either V1 or V2 receptors.(ABSTRACT TRUNCATED AT 250 WORDS)
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Murdock, Lindsay, Tangi Burke, Chelsea Coumoundouros, Doreen E. Culham, Charles E. Deutch, James Ellinger, Craig H. Kerr, et al. "Analysis of Strains Lacking Known Osmolyte Accumulation Mechanisms Reveals Contributions of Osmolytes and Transporters to Protection against Abiotic Stress." Applied and Environmental Microbiology 80, no. 17 (June 20, 2014): 5366–78. http://dx.doi.org/10.1128/aem.01138-14.
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ABSTRACTOsmolyte accumulation and release can protect cells from abiotic stresses. InEscherichia coli, known mechanisms mediate osmotic stress-induced accumulation of K+glutamate, trehalose, or zwitterions like glycine betaine. Previous observations suggested that additional osmolyte accumulation mechanisms (OAMs) exist and their impacts may be abiotic stress specific. Derivatives of the uropathogenic strain CFT073 and the laboratory strain MG1655 lacking known OAMs were created. CFT073 grew without osmoprotectants in minimal medium with up to 0.9 M NaCl. CFT073 and its OAM-deficient derivative grew equally well in high- and low-osmolality urine pools. Urine-grown bacteria did not accumulate large amounts of known or novel osmolytes. Thus, CFT073 showed unusual osmotolerance and did not require osmolyte accumulation to grow in urine. Yeast extract and brain heart infusion stimulated growth of the OAM-deficient MG1655 derivative at high salinity. Neither known nor putative osmoprotectants did so. Glutamate and glutamine accumulated after growth with either organic mixture, and no novel osmolytes were detected. MG1655 derivatives retaining individual OAMs were created. Their abilities to mediate osmoprotection were compared at 15°C, 37°C without or with urea, and 42°C. Stress protection was not OAM specific, and variations in osmoprotectant effectiveness were similar under all conditions. Glycine betaine and dimethylsulfoniopropionate (DMSP) were the most effective. Trimethylamine-N-oxide (TMAO) was a weak osmoprotectant and a particularly effective urea protectant. The effectiveness of glycine betaine, TMAO, and proline as osmoprotectants correlated with their preferential exclusion from protein surfaces, not with their propensity to prevent protein denaturation. Thus, their effectiveness as stress protectants correlated with their ability to rehydrate the cytoplasm.