Biological Membrane System Research Articles

Highly Efficient, Stable, and Easily Detachable Biological Membrane System Inspired by Water Hyacinth

Highly Efficient, Stable, and Easily Detachable Biological Membrane System Inspired by Water Hyacinth

"Cluster Bomb" Based on Redox-Responsive Carbon Dot Nanoclusters Coated with Cell Membranes for Enhanced Tumor Theranostics.

Designing intelligent stimuli-responsive nanoplatforms that are integrated with a biological membrane system and nanomaterials to realize efficient imaging and therapy of tumors still remains to be challenging. Herein, we report a unique strategy to prepare redox-responsive yellow fluorescent carbon dot nanoclusters (y-CDCs) loaded with anticancer drug doxorubicin (DOX) and coated with the cancer cell membrane (CCM) for precision fluorescence imaging and homologous targeting chemotherapy of tumors. The y-CDs with a size of 7.2 nm were first synthesized via a hydrothermal method and crosslinked to obtain redox-responsive y-CDCs with a size of 150.0 nm. The formulated y-CDCs were physically loaded with DOX with an efficiency of up to 81.0% and coated with CCM to endow them with antifouling properties, immune escape ability to escape from macrophage uptake, and homologous targeting capability to cancer cells. Within the reductive tumor microenvironment, the y-CDCs with quenched fluorescence can dissociate to form single y-CDs with recovered fluorescence and improved tumor penetration ability and simultaneously release DOX from the "cluster bomb", thus realizing efficient targeted tumor fluorescence imaging and chemotherapy. The designed y-CDCs/DOX@CCM may represent an updated nanomedicine formulation based on CDs for improved theranostics of different types of tumors.

Reclaimed water application to vegetation restoration in mining area: Determination of water quality standards and optimization of moderate treatment technology

Water shortage severely restricts vegetation restoration of mining area in the northwest China. Moderate treatment of reclaimed water is essential for improving the local ecological environment. In this study, relevant water quality standards issued by the states and research results were comprehensively considered to propose a reclaimed water quality standard suitable for vegetation restoration of mining area. The available domestic sewage and mine water was moderately treated by hybrid biological reactor system and nanofiltration membrane system, respectively. The effluent quality meet the requirement of reclaimed water quality standards in this study. This study provides theoretical support for vegetation restoration of mining area.

The Role of Protein-Lipid Interactions in the Functioning of Bitopic Membrane Proteins

The biological function of bitopic membrane proteins, having only one transmembrane segment, provides a variety of intermolecular interactions on the cell membrane. Bitopic receptors of type I are directly involved in the development and maintenance of homeostasis of tissues of the human body. Epidermal growth factor receptor (EGFR/HER) and growth hormone (GHR) receptors serve as convenient models of type I receptors to show how ligand-induced conformational rearrangements and specific dimerization of extracellular and TM domains lead to allosteric activation of cytoplasmic domains during signal transmission through the cell membrane. Disfunctioning of these receptors leads to the development of a number of human pathologies. RTK inhibitors are one of the most successful examples of targeted cancer therapy today. At the same time, Alzheimer's disease is an age-related pathology associated with the accumulation of β-amyloid peptides, - products of enzymatic cleavage by membrane sites of the amyloid precursor protein (APP). Over the several years, we experimentally determined alternative β-protein conformations in the membrane regions and TM domains of the EGFR/HER, GHR, and APP proteins in membrane-like media using high-resolution NMR spectroscopy in combination with MD relaxation. According to the recent biophysical and biochemical data, it has been shown that the functioning of these bitopic proteins is determined not only by specific protein-protein and protein-lipid interactions, but also by the physical state of the lipid environment, as one of the main components of the self-consistent biological membrane system. This allowed us to propose new principles that underlie signal transmission through the cell membrane and substrate recognition by membrane proteins, as well as the mechanisms of action of a number of pathogenic mutations in the TM domains of proteins. This work was supported by the Russian Science Foundation (project 18-14-00375).

CHARMM-GUI Membrane Builder for Complex Biological Membrane Simulations with Glycolipids and Lipoglycans.

Glycolipids (such as glycoglycerolipids, glycosphingolipids, and glycosylphosphatidylinositol) and lipoglycans (such as lipopolysaccharides (LPS), lipooligosaccharides (LOS), mycobacterial lipoarabinomannan, and mycoplasma lipoglycans) are typically found on the surface of cell membranes and play crucial roles in various cellular functions. Characterizing their structure and dynamics at the molecular level is essential to understand their biological roles, but systematic generation of glycolipid and lipoglycan structures is challenging because of great variations in lipid structures and glycan sequences (i.e., carbohydrate types and their linkages). To facilitate the generation of all-atom glycolipid/LPS/LOS structures, we have developed Glycolipid Modeler and LPS Modeler in CHARMM-GUI ( http://www.charmm-gui.org ), a web-based interface that simplifies building of complex biological simulation systems. In addition, we have incorporated these modules into Membrane Builder so that users can readily build a complex symmetric or asymmetric biological membrane system with various glycolipids and LPS/LOS. These tools are expected to be useful in innovative and novel glycolipid/LPS/LOS modeling and simulation research by easing tedious and intricate steps in modeling complex biological systems and shall provide insight into structures, dynamics, and underlying mechanisms of complex glycolipid-/LPS-/LOS-containing biological membrane systems.

Effect of different ethanolic concentrations on antioxidant properties and cytoprotective activities of Platostoma palustre Blume

The objective of this study was to evaluate the antioxidant activities of Mesona procumbens ethanolic extracts (MPEEs) which displayed variable antioxidant levels with different ethanolic concentrations. Compared to MPEEs with 20, 40 and 80% ethanol, the 60% MPEE exhibited a higher total phenol content (TPC), total flavonoid content (TFC), 1,1-diphenyl-2-picryl hydrazyl (DPPH)- and 2,2-azino-bis-(3-ethyl benzothiazoline-6-sulphonic acid (ABTS)-scavenging activities, reducing power, protection of Raw 264.7 mouse macrophages against H2O2-induced damage, and inhibition of reactive oxygen species (ROS) induced by 2,2-azobis(2-amidino propane) dihidrochloride (AAPH). IC50 values of DPPH and ABTS radicals by MPEEs were highly and significantly associated with TPCs and TFCs. The most significant protective effect against oxidative DNA damage was also found to be the 60% MPEE at a concentration of 3.6 mg/mL. In addition, the cell viability test showed that none of the MPEEs had any cell toxicity up to a concentration of 250 μg/mL. The 60% MPEE exhibited higher in vitro and ex vivo antioxidant activities, possessed a protective capability for the biological membrane system, and can be used as a functional ingredient representing a potential source of natural antioxidants to prevent and treat oxidative stress-related disorders.

Wastewater treatment in submerged aerated biofilter under condition of high ammonium concentration

Abstract Treatment of wastewater produced in Service Areas (SA) located on expressways and highways is a worldwide problem because of increasing amount of roads and specific composition of those kinds of sewage. Insufficient removal of pollutants from wastewater discharged into surface water may cause serious environmental problems. In the present study efficiency of treatment of wastewater with high ammonium concentration in biological membrane system used on SA was investigated. Concentrations of ammonia nitrogen in wastewater flowing into bioreactor in none of the tested objects did not fall below 99.0 mg of N-NH4·dm−3. Because of high ammonium content in sewage and high pH reaching value about 9, it is almost impossible to create favorable conditions for microorganisms that run purification processes resulting in low efficiency of phosphorus and nitrogen removal (reduction of biogenic compounds did not exceed 15%). Treatment of wastewater consisting mainly of urine with commonly used biological membrane technology has to be widely tested to perform suitable quality of discharged wastewater, to provide safety of surface water environment.

Interactions between magnetic nanoparticles and model lipid bilayers—Fourier transformed infrared spectroscopy (FTIR) studies of the molecular basis of nanotoxicity

The toxicity of nanoparticles (nanotoxicity) is often associated with their interruption of biological membranes. The effect of polymer-coated magnetic nanoparticles (with different Fe3O4 core sizes and different polymeric coatings) on a model biological membrane system of vesicles formed by dimyristoylphosphatidylcholine (DMPC) was studied. Selected magnetic nanoparticles with core sizes ranging from 3 to 13 nm (in diameter) were characterised by transmission electron microscopy. Samples with 10% DMPC and different nanoparticle concentrations were studied by attenuated total reflectance—Fourier transform infrared spectroscopy to establish the influence of nanoparticles on the phase behaviour of model phospholipid systems.

Nitrogen Removal along Vertical direction by Plant Biological Membrane System

Based on the equipment of integrated constructed wetlands (ICWs) with independent intellectual property rights. Plant biological membrane system (PBMS) was constructed to purify nitrogen of sanitary sewage. PBMS includes palm silk, non-woven and floating plant (Trifolium repens L.). Total nitrogen (TN), ammonia nitrogen (NH3-N) was investigated to evaluate the effects of the layered purification and resistance to the outside impact. The results showed that layered purification occurred along the flowing vertical direction. The average removal rate of TN, NH3-N and total dissolved solids was 65.6%, 60.7% and 38.7%, respectively. The TN and NH3-N removal load of the lower, middle and upper layer were 1.0, 0.8, 0.7g/ (m2.d) and 0.8, 0.8, 0.3g/ (m2.d), respectively. The higher concentration of inflow the stronger resists impact load capability. The TN and NH3-N average removal load of the lower, middle and upper layer were 4.1, 1.88, 1.57 times and 3.13, 1.25, 1 time than those of the stable phase, respectively.

Polar Residues and Their Positional Context Dictate the Transmembrane Domain Interactions of Influenza A Neuraminidases

Interactions that facilitate transmembrane domain (TMD) dimerization have been identified mainly using synthetic TMDs. Here, we investigated how inherent properties within natural TMDs modulate their interaction strength by exploiting the sequence variation in the nine neuraminidase subtypes (N1-N9) and the prior knowledge that a N1 TMD oligomerizes. Initially, consensus TMDs were created from the influenza A virus database, and their interaction strengths were measured in a biological membrane system. The TMD interactions increased with respect to decreasing hydrophobicity across the subtypes (N1-N9) and within the human N1 subtype where the N1 TMDs from the pandemic H1N1 strain of swine origin were found to be significantly less hydrophobic. The hydrophobicity correlation was attributed to the conserved amphipathicity within the TMDs as the interactions were abolished by mutating residues on the polar faces that are unfavorably positioned in the membrane. Similarly, local changes enhanced the interactions only when a larger polar residue existed on the appropriate face in an unfavorable membrane position. Together, the analysis of this unique natural TMD data set demonstrates how polar-mediated TMD interactions from bitopic proteins depend on which polar residues are involved and their positioning with respect to the helix and the membrane bilayer.

The Regeneration Water Research Based on the Characteristics of Jiangnan Water in the Green Ecological Building Area

The recycled water is the important way to solve the shortage of water resources. In China the recycled water use in the jiangnan region is still in start level, rare setting up reclaimed water system inside the village . According to designing water system in jiangnan area, using the high quality miscellaneous drainage for raw water, filtering the all sizes of particle in water, and adopting the biological membrane system decompose the organic therein, the water after disinfection can be as the non potable water. This water system is simple in technology, not occupying the land, four years of recyclable cost and the operation maintenance costs are low.

The investigation of dairy industry wastewater treatment in a biological high performance membrane system

The dairy industry is generally considered to be the largest source of food processing wastewater in many countries. The highly variable nature of dairy wastewaters in terms of volumes and flowrates and in terms of high organic materials contents such as COD 921–9004 mg L −1, BOD 483–6080 mg L −1, TN of 8–230 mg L −1 and SS of 134–804 mg L −1 makes the choice of an effective wastewater treatment regime difficult. A high performance bioreactor, an aerobic jet loop reactor, combined with a ceramic membrane filtration unit, was used to investigate its suitability for the treatment of the dairy processing wastewater. The oxygen transfer rates of the bioreactor were found to be very high (100–285 h −1) on the operating conditions. A loading rate of 53 kg COD m −3 d −1 resulted in 97–98% COD removal efficiencies under 3 h hydraulic retention time. The high MLSS concentrations could be retained in the system (up to 38,000 mg L −1) with the contribution of UF (ultrafiltration) unit. During the filtration of activated sludge, the fluxes decreased with increasing MLSS. Cake formation fouling was determined as dominant fouling mechanisms. The results demonstrate that jet loop membrane bioreactor system was a suitable and effective treatment choice for treating dairy industry wastewater.

Comparison of the antioxidant properties of emu oil with other avian oils

The antioxidant properties of emu oil were compared with oils derived from the fat of other avian species. We first examined their free radical scavenging activity against the 2,2-diphenyl-1-picryl hydracyl radical. The concentration of emu oil in the test solution that caused 50% neutralisation (IC50) was variable (24.5 ± 5.9 mg/mL, range 5.3–55.4 mg/mL), but similar to values obtained for other ratites (10.7 ± 5.9 mg/mL). In contrast, the IC50 values for duck and chicken oil were much higher (118.0 ± 8.1 mg/mL). The variability in the radical scavenging activity of emu oil preparations may reflect variations in the diets of the birds, the processing protocol and/or the storage age of the oil. We also evaluated some of the ratite oils for their inhibitory capacity on human erythrocyte membrane oxidation, by measuring the reduction of the thiobarbituric acid-reactive substance (TBAR) production. Emu oil had a greater effect in decreasing TBAR production than either the ostrich or rhea oil, suggesting that it offers more protection than the other ratite oils against oxidative damage. In conclusion, we demonstrated that emu oil has both antioxidant properties in vitro and a protective role against oxidative damage in a model biological membrane system. The antioxidant or radical scavenging properties of emu oil appear to be due to minor constituents in the non-triglyceride fraction of the oil, while its high ratio of unsaturated to saturated fatty acids (UFA : SFA) offers protection against oxidative damage.

Electron capture negative chemical ionization mass spectrometry and tandem mass spectrometry analysis of β‐carotene, α‐tocopherol and their oxidation products

AbstractThe biological antioxidants α‐tocopherol, 1, and β‐carotene, 4, and products of their antioxidant reactions are potentially important indicators of biological antioxidant status and functions. Electron capture by compounds 1 and 4 and their oxidation products yields intense molecular anions with little fragmentation. Collision‐induced dissociation of the molecular anions was studied by linked‐scaning (B/E = constant) on a reverse‐geometry magnetic‐sector mass spectrometer. Both 1 and 4 and their products undergo extensive diagnostic cleavages of their hydrocarbon chains, apparently via charge‐remote fragmentation. Electron capture negative chemical ionization mass spectrometry appears uniquely suited to structure identification studies of antioxidants and their oxidation products. This methodology is used to identify oxidation products of 1 and 4 from a model biological membrane system subjected to peroxyl radical attack.

Lipid bilayers: membrane-protein electrostatic interactions: Current Opinion in Structural Biology 1991, 1:185–190

In the past year, several studies have characterized the energetics of peptide binding to charged membranes. The results of this and other work suggest a role for electrostatics in fundamental processes, such as the folding of membrane proteins. An electrostatic mechanism has also been shown to be responsible for lipid asymmetry in a biological membrane system.

Universality in interacting membranes: The effect of cosurfactants on the interfacial rigidity.

We report on synchrotron x-ray scattering studies of multimembrane systems in the fluid L/sub ..cap alpha../ phase. By embedding cosurfactant molecules in a model biological membrane (di-myristoyl-phosphoridyl-choline) system, we dramatically reduce the bending rigidity of the fluid bilayer. This effect leads to a crossover from a microscopically driven to a fluctuation-induced universal regime for intermembrane interactions. Studies of a homologous cosurfactant series, with varying hydrocarbon chain length between 5 and 12, allow us to attribute this reduction in k/sub c/ to the thinning of the membrane.

The alteration of rabbit skeletal sarcoplasmic reticulum function by N-acylethanolamine, a lipid associated with myocardial infarction

The ability of N-acylethanolamines (pharmacologically active lipid metabolites which accumulate in canine myocardium during experimentally induced infarctions) to alter Ca 2+ fluxes in a biological membrane system was studied using sarcoplasmic reticulum vesicles prepared from rabbit skeletal muscle. The effects of two N-acylethanolamines, the N-oleyl and N-lauryl derivatives, were compared to those of the lipophilic drugs, dibucaine and propranolol. The rate and extent of Ca 2+ sequestration, Ca 2+-Mg 2+-ATPase activity and retention time of Ca 2+ by the vesicles were all stimulated at low concentrations of the four compounds studied and inhibited at higher concentrations. The stoichiometry between Ca 2+-pumping rates and ATPase activity was partially “uncoupled” indicating that both the calcium pump and the membrane permeability were affected by the drugs. However, although all four compounds exhibited the same qualitative behavior, the effects of the two N-acylethanolamines were more pronounced than dibucaine and propranolol and occurred at much lower concentrations. These results suggest that the N-acylethanolamines may have important physiological effects in the myocardium and, at least at lower concentrations, stimulate myocardial contractility by increasing the rate of calcium flux across the sarcoplasmic reticulum.

96] Proton, carbon-13, and phosphorus-31 NMR methods for the investigation of rhodopsin-lipid interactions in retinal rod outer segment membranes

This chapter discusses the nuclear magnetic resonance (nmr) methods for the investigation of rhodopsin–lipid interactions in retinal rod outer segment (ROS) membranes. The rhodopsin-containing disk membranes of the retinal ROS represent an attractive model for the study of lipid–protein interactions in a native biological membrane system. The native ROS membrane phospholipid composition is well characterized, and a number of intriguing problems relating to the structural and functional role of the highly polyunsaturated ROS phospholipids are evident, which appear amenable to investigation using biophysical techniques. NMR spectra of good quality and resolution can be obtained from photoreceptor membrane preparations, so that their phospholipid organization and dynamic properties can be investigated in a manner quite analogous to nmr studies of simpler model lipid bilayer systems. NMR is a useful analytical tool for characterizing the isolated ROS membrane components.