We present a method for finely adjustable electroosmotic flow (EOF) velocity in cathodic direction for the optimization of separations in capillary electrophoresis. To this end, we use surface modification of the separation fused silica capillary by the covalently attached copolymer of acrylamide (AM) and 2-acrylamido-2-methyl-1-propanesulfonate (AMPS), that is, poly(AM-co-AMPS) or PAMAMPS. Coatings were formed by the in-capillary polymerization of a mixture of the neutral AM and anionic AMPS monomers premixed in various ratios in order to control the charge density of the copolymer. EOF mobility varies in the 0 to ∼40 × 10-9 m2 V-1 s-1 interval for PAMAMPS coatings ranging from 0 to 60 mol.% of charged AMPS monomer. For EOF in PAMAMPS-treated capillaries, we observed (i) a negligible dependence on pH in the 2-10 interval, (ii) a minor variance among background electrolytes (BGEs) in function of their components and (iii) its standard decrease with increasing ionic strength of the BGE. Interest in variable cathodic EOF was demonstrated by the amelioration of separation of two kinds of isomeric anionic analytes, that is, monosaccharides phosphates and helquat enantiomers, in counter-EOF mode.
Electroosmotic flow (EOF) plays a pivotal role in optimization of capillary electrophoresis (CE) separations of (bio)molecules and (bio)particles. EOF velocity is directly related to analysis time, peak resolution and separation efficiency. Here, we report a concept of charged polymer coatings of the inner fused silica capillary wall, which allows anodic EOF with mobility ranging from 0 to ∼(30-40) × 10-9 m2V-1s-1. The capillary wall is modified by covalently bound cationic copolymer poly(acrylamide-co-(3-acrylamidopropyl)trimethylammonium chloride) (PAMAPTAC) containing variable ratio of the charged monomer in the 0-60 mol. % interval. The EOF mobility showed minor variability with composition of background electrolyte (BGE) and pH in the 2-10 interval. The coatings were evaluated by CE-UV and nanospray CE-MS in the counter-EOF arrangement for a series of basic drug molecules in acetic acid based acidic BGE. Tunable EOF velocity was demonstrated as a useful tool for optimization of peak resolution, separation efficiency and migration time of analytes. Electrostatic repulsion of positively charged capillary surface was shown as beneficial for suppression of analyte adsorption, notably for hydrophobic cationic analytes.
- MeSH
- adsorpce MeSH
- elektroforéza kapilární * MeSH
- elektroosmóza * MeSH
- kationty MeSH
- polymery MeSH
- Publikační typ
- časopisecké články MeSH
Polyhydroxyalkanoates are microbial polyesters which are considered being biological alternatives to petrochemical polymers. Extremophiles, such as thermophilic PHA producers, hold promise to improve competitiveness of PHA production process. Therefore, this work aimed at isolation of new strains, which could produce PHA under elevated temperature. Since traditional Nile red staining of colonies provided false positive results in thermophiles, we developed a novel strategy of enriching microbial consortia by PHA producers. This so called "osmoselective strategy" is based on application of osmotic challenge by sudden exposition of the mixed microbial culture to hypertonic and subsequently to hypotonic conditions; moreover, this strategy relies on the fact that PHA protect bacteria from negative effects of rapid fluctuations in osmotic pressure. In combination with fast and reliable ATR-FTIR inspection of selected colonies for presence of PHA, we were able to isolate several promising thermophilic or thermotolerant PHA producing strains belonging to the genera Bacillus, Aneurinibacillus and Chelatococcus, which indeed deserves further investigation to evaluate their potential for industrial production of PHA.
- MeSH
- Alphaproteobacteria izolace a purifikace MeSH
- Bacillales izolace a purifikace MeSH
- Bacillus izolace a purifikace MeSH
- Bacteria izolace a purifikace MeSH
- bioreaktory MeSH
- DNA bakterií MeSH
- fermentace MeSH
- mikrobiální společenstva * MeSH
- osmóza MeSH
- polyhydroxyalkanoáty chemie MeSH
- sekvence nukleotidů MeSH
- termotolerance MeSH
- vysoká teplota MeSH
- Publikační typ
- časopisecké články MeSH
Electrophoretic focusing on an inverse electromigration dispersion (EMD) profile is based on a principle different from those of other electrophoretic separation methods. It has already proved its applicability in analytical practice by offering competitive separation performance and sensitivity and specific selectivity. It can be classified as an intermediate between field-driven and equilibrium gradient methods and is therefore interesting from the viewpoint of theory of separation methods. This work presents a comprehensive theoretical description of electrophoretic focusing on an inverse EMD profile comprising properties of the electrolyte system, formed gradients, and focused analyte zones. The separation properties are described in terms of resolution and peak capacity and their dependence on system and analyte properties is discussed from the viewpoint of how the counteracting phenomena of electromigration and dispersion are affected by electric current, voltage, and hydrodynamic and electroosmotic flow. The overall performance of the present method is shown to be comparable with other electrophoretic separation methods like zone electrophoresis or isoelectric focusing.
High-frequency ultrasound is used in this study to measure noninvasively, by means of osmotic loading, changes in speed of sound and cartilage thickness caused by variations of the salt concentration in the external bath. Articular cartilage comprises three main structural components: Water, collagen fibrils and proteoglycan macromolecules carrying negative charges. The negatively charged groups of proteoglycans attract cations and water into tissue and govern its shrinkage/swelling behavior, which is a fundamental mechano-electrochemical function of cartilage tissue. In this study, the mechano-electrochemical behavior of cartilage is modeled by a diffusion model. The proposed model enables simulations of cartilage osmotic loading under various parameter settings and allows to quantify cartilage mechanical properties. This theoretical model is derived from the kinetic theory of diffusion. The objectives of the study are to quantify time dependent changes in cartilage thickness, and in speed of sound within tissue with help of the finite element based simulations and data from experiments. Experimental data are obtained from fresh and trypsinized ovine patella samples. Results show that the proposed diffusion model is capable to describe transient osmotic loading of cartilage. Mean values and their deviations of the relative changes of cartilage characteristics in response to chemical loading are presented.
- MeSH
- biologické modely * MeSH
- kloubní chrupavka * diagnostické zobrazování MeSH
- osmóza MeSH
- ovce MeSH
- proteoglykany MeSH
- ultrasonografie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Peptides derived from non-functional precursors play important roles in various developmental processes, but also in (a)biotic stress signaling. Our (phospho)proteome-wide analyses of C-TERMINALLY ENCODED PEPTIDE 5 (CEP5)-mediated changes revealed an impact on abiotic stress-related processes. Drought has a dramatic impact on plant growth, development and reproduction, and the plant hormone auxin plays a role in drought responses. Our genetic, physiological, biochemical, and pharmacological results demonstrated that CEP5-mediated signaling is relevant for osmotic and drought stress tolerance in Arabidopsis, and that CEP5 specifically counteracts auxin effects. Specifically, we found that CEP5 signaling stabilizes AUX/IAA transcriptional repressors, suggesting the existence of a novel peptide-dependent control mechanism that tunes auxin signaling. These observations align with the recently described role of AUX/IAAs in stress tolerance and provide a novel role for CEP5 in osmotic and drought stress tolerance.
- MeSH
- Arabidopsis genetika metabolismus fyziologie MeSH
- biologický transport genetika MeSH
- fosfoproteiny metabolismus MeSH
- fyziologická adaptace * genetika MeSH
- fyziologický stres * genetika MeSH
- genetická transkripce MeSH
- kyseliny indoloctové metabolismus MeSH
- období sucha MeSH
- osmóza MeSH
- peptidy metabolismus MeSH
- proteasomový endopeptidasový komplex metabolismus MeSH
- proteiny huseníčku metabolismus MeSH
- proteom metabolismus MeSH
- proteomika * MeSH
- regulace genové exprese u rostlin MeSH
- semenáček růst a vývoj MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
Polyhydroxyalkanoates (PHA) are microbial polyesters which accumulate as intracellular granules in numerous prokaryotes and mainly serve as storage materials; beyond this primary function, PHA also enhance the robustness of bacteria against various stress factors. We have observed that the presence of PHA in bacterial cells substantially enhances their ability to maintain cell integrity when suddenly exposed to osmotic imbalances. In the case of the non-halophilic bacterium Cupriavidus necator, the presence of PHA decreased plasmolysis-induced cytoplasmic membrane damage during osmotic up-shock, which subsequently enabled the cells to withstand subsequent osmotic downshock. In contrast, sudden induction of osmotic up- and subsequent down-shock resulted in massive hypotonic lysis of non-PHA containing cells as determined by Transmission Electron Microscopy and Thermogravimetrical Analysis. Furthermore, a protective effect of PHA against hypotonic lysis was also observed in the case of the halophilic bacterium Halomonas halophila; here, challenged PHA-rich cells were capable of retaining cell integrity more effectively than their PHA-poor counterparts. Hence, it appears that the fact that PHA granules, as an added value to their primary storage function, protect halophiles from the harmful effect of osmotic down-shock might explain why PHA accumulation is such a common feature among halophilic prokaryotes. The results of this study, apart from their fundamental importance, are also of practical biotechnological significance: because PHA-rich bacterial cells are resistant to osmotic imbalances, they could be utilized in in-situ bioremediation technologies or during enrichment of mixed microbial consortia in PHA producers under conditions of fluctuating salinity.
- MeSH
- Bacteria cytologie účinky léků metabolismus MeSH
- Cupriavidus necator cytologie účinky léků metabolismus ultrastruktura MeSH
- Halomonas cytologie účinky léků metabolismus ultrastruktura MeSH
- mikrobiální viabilita účinky léků MeSH
- osmóza * MeSH
- polyhydroxyalkanoáty farmakologie MeSH
- teplota MeSH
- termogravimetrie MeSH
- Publikační typ
- časopisecké články MeSH
Over the past few decades, reverse osmosis (RO) has been the dominant technology employed in zero liquid discharge (ZLD) systems for industrial wastewater treatment (WWT). However, RO is limited to a maximum operating salinity of about 75 g kg-1. Electrodialysis (ED) is a potentially attractive option as it can achieve much higher concentrations, thereby reducing the capacity and energy demand of the subsequent evaporation step. Feed-and-bleed experiments were undertaken on a laboratory-scale ED stack using a series of model solutions based on the most common inorganic salts with the aim of determining maximum achievable concentrations. The maximum salt concentration achievable via ED ranged between 104.2 and 267.6 g kg-1, with levels predominantly limited by water transport. In addition, a straightforward review of how ED incorporation can affect ZLD process economics is presented. The operational cost of an ED-based ZLD system for processing RO retentate was almost 20% lower than comparable processes employing high-efficiency RO and disc tubular RO. As the ED-based ZLD system appears economically preferable, and as maximum achievable concentrations greatly exceeded RO operating limits, it would appear to be a promising approach for bridging the gap between RO and evaporation, and may even eliminate the evaporation step altogether.
During plant growth and defense, cell cycle activity needs to be coordinated with cell wall integrity. Little is known about how this coordination is achieved. Here, we investigated coordination in Arabidopsis thaliana seedlings by studying the impact of cell wall damage (CWD, caused by cellulose biosynthesis inhibition) on cytokinin homeostasis, cell cycle gene expression and cell shape in root tips. CWD inhibited cell cycle gene expression and increased transition zone cell width in an osmosensitive manner. These results were correlated with CWD-induced, osmosensitive changes in cytokinin homeostasis. Expression of CYTOKININ OXIDASE/DEHYDROGENASE 2 and 3 (CKX2, CKX3), which encode cytokinin-degrading enzymes, was induced by CWD and reduced by osmoticum treatment. In nitrate reductase1 nitrate reductase2 (nia1 nia2) seedlings, CKX2 and CKX3 transcript levels were not increased and cell cycle gene expression was not repressed by CWD. Moreover, established CWD-induced responses, such as jasmonic acid, salicylic acid and lignin production, were also absent, implying a central role of NIA1/2-mediated processes in regulation of CWD responses. These results suggest that CWD enhances cytokinin degradation rates through a NIA1/2-mediated process, leading to attenuation of cell cycle gene expression.
- MeSH
- Arabidopsis cytologie účinky léků genetika MeSH
- benzamidy farmakologie MeSH
- biologické modely MeSH
- buněčná stěna účinky léků metabolismus MeSH
- buněčný cyklus účinky léků genetika MeSH
- cytokininy farmakologie MeSH
- fenotyp MeSH
- homeostáza účinky léků MeSH
- kořeny rostlin cytologie účinky léků růst a vývoj MeSH
- messenger RNA genetika metabolismus MeSH
- nitrátreduktasa metabolismus MeSH
- osmóza MeSH
- proteiny huseníčku metabolismus MeSH
- regulace genové exprese u rostlin * účinky léků MeSH
- semenáček účinky léků genetika MeSH
- sorbitol farmakologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Part I on head-column field-amplified sample stacking comprised a detailed study of the electrokinetic injection of a weak base across a short water plug into a phosphate buffer at low pH. The water plug is converted into a low conductive acidic zone and cationic analytes become stacked at the interface between this and a newly formed phosphoric acid zone. The fundamentals of electrokinetic processes occurring thereafter were studied experimentally and with computer simulation and are presented as part II. The configuration analyzed represents a discontinuous buffer system. Computer simulation revealed that the phosphoric acid zone at the plug-buffer interface becomes converted into a migrating phosphate buffer plug which corresponds to the cationically migrating system zone of the phosphate buffer system. Its mobility is higher than that of the analytes such that they migrate behind the system zone in a phosphate buffer comparable to the applied background electrolyte. The temporal behaviour of the current and the conductivity across the water plug were monitored and found to reflect the changes in the low conductivity plug. Determination of the buffer flow in the capillary revealed increased pumping caused by the mismatch of electroosmosis within the low conductivity plug and the buffer. This effect becomes elevated with increasing water plug length. For plug lengths up to 1% of the total column length the flow quickly drops to the electroosmotic flow of the buffer and simulations with experimentally determined current and flow values predict negligible band dispersion and no loss of resolution for both low and large molecular mass components.
