Plasma membrane-anchored fluorescent tracker based on boron-dipyrromethene

The construction of a stable-membrane tracker has significant implications for the visualization of the membrane in live cells.However,most current plasma trackers are not suitable for tracking plasma membranes for a long time due to their limited retention time.Herein,Mem580-F-Sulfo is designed to target and anchor cell membranes and therefore track cell membranes for a longer time.This tracker is composed of a lipophilic boron-dipyrromethene(BODIPY)derivative and a hydrophilic zwitterion to form an amphiphilic structure,which enables its targeting ability toward cell membranes.Moreover,a reactive ester group is included to bind with proteins through covalent bonds in cell membranes nonspecifically,which extends retention time in cell membranes.Mem580-F-Sulfo shows intense brightness(94600),with a high molar absorption coefficient of up to about 100000 L·mol^(-1)·cm^(-1)and a fluorescence quantum yield of up to 0.97.It shows fast cell membrane targeting ability and long retention up to 90 min.In brief,this work has not only developed a tracker with good cell membrane targetability but also provided a new strategy for improving the targeting stability of cell membranes.

Identification of P-type plasma membrane H^(+)-ATPases in common wheat and characterization of TaHA7 associated with seed dormancy and germination

The P-type plasma membrane(PM)H^(+)-ATPases(HAs)are crucial for plant development,growth,and defense.The HAs have been thoroughly characterized in many different plants.However,despite their importance,the functions of HAs in germination and seed dormancy(SD)have not been validated in wheat.Here,we identified 28 TaHA genes(TaHA1-28)in common wheat,which were divided into five subfamilies.An examination of gene expression in strong-and weak-SD wheat varieties led to the discovery of six candidate genes(TaHA7/-12/-14/-16/-18/-20).Based on a single nucleotide polymorphism(SNP)mutation(C/T)in the TaHA7 coding region,a CAPS marker(HA7)was developed and validated in 168 wheat varieties and 171 Chinese mini-core collections that exhibit diverse germination and SD phenotypes.We further verified the roles of the two allelic variations of TaHA7 in germination and SD using wheat mutants mutagenized with ethyl methane sulphonate(EMS)in‘Jimai 22’and‘Jing 411’backgrounds,and in transgenic Arabidopsis lines.TaHA7 appears to regulate germination and SD by mediating gibberellic acid(GA)and abscisic acid(ABA)signaling,metabolism,and biosynthesis.The results presented here will enable future research regarding the TaHAs in wheat.

Plasma‐oxidized 2D MXenes subnanochannel membrane for high‐performance osmotic energy conversion

Nanofluidic channels inspired by electric eels open a new era of efficient harvesting of clean blue osmotic energy from salinity gradients.Limited by less charge and weak ion selectivity of the raw material itself,energy conversion through nanofluidic channels is still facing considerable challenges.Here,a facile and efficient strategy to enhance osmotic energy harvesting based on drastically increasing surface charge density of MXenes subnanochannels via oxygen plasma is proposed.This plasma could break Ti–C bonds in the MXenes subnanochannels and effectively facilitate the formation of more Ti–O,C═O,O–OH,and rutile with a stronger negative charge and work function,which leads the surface potential of MXenes membrane to increase from 205 to 430 mV.This significant rise of surface charge endows the MXenes membrane with high cation selectivity,which could make the output power density of the MXenes membrane increase by 248.2%,reaching a high value of 5.92Wm^(−2)in the artificial sea‐river water system.Furthermore,with the assistance of low‐quality heat at 50℃,the osmotic power is enhanced to an ultrahigh value of 9.68Wm^(−2),which outperforms those of the state‐of‐the‐art two‐dimensional(2D)nanochannel membranes.This exciting breakthrough demonstrates the enormous potential of the facile plasma‐treated 2D membranes for osmotic energy harvesting.

Enhancing CO_(2) transport with plasma-functionalized ionic liquid membranes

The ionic liquid(IL) 1-butyl-3-methylimidazolium tetrafluoroborate treated with radiofrequency plasma is proposed for functionalization and immobilization on polyethersulfone supports to form supported ionic liquid membranes for CO_(2) separation.The effects of treatment time and transmembrane pressure difference on CO_(2) permeance were evaluated.The best gas permeation performance was obtained with a treatment time of 10 min and the transmembrane pressure difference was 0.25 MPa.Characterization of the materials by Fourier transform infrared spectroscopy,x-ray photoelectron spectroscopy and nuclear magnetic resonance spectroscopy demonstrates that the IL is grafted with carboxyl groups and deprotonated through plasma treatment.A preliminary mechanism for the plasma treatment and facilitated transport of CO_(2)has been proposed on this basis.

Hydrogen Permeation Characteristics of Pd-CuMembrane in Plasma Membrane Reactor

Hydrogen is an alternative energy source that has the potential to replace fossil fuels.One of the hydrogen applications is as a material for Polymer Electrolyte Membrane Fuel Cells(PEMFC)in fuel cell vehicles.High-purity hydrogen can be obtained using a hydrogen separation membrane to prevent unwanted contaminants from potentially harming the PEMFC components.In this study,we fabricated a plasma membrane reactor and investigated the permeation performance of a hydrogen separation membrane in a plasma membrane reactor utilizing atmospheric pressure plasma.The result showed the hydrogen permeation rate increasing with time as reactor temperature is increased through joule heating.By decreasing the gap length of the reactor from 2 to 1 mm,the hydrogen permeation rate increases by up to 40%.The hydrogen permeation rate increases by 30%when pressure is applied to the plasma membrane reactor by up to 100 kPa.

Functional analysis of MdSUT2.1,a plasma membrane sucrose transporter from apple

Sugar content is a determinant of apple(Malus×domestica Borkh.)sweetness.However,the molecular mechanism underlying sucrose accumulation in apple fruit remains elusive.Herein,this study reported the role of the sucrose transporter MdSUT2.1 in the regulation of sucrose accumulation in apples.The MdSUT2.1 gene encoded a protein with 612 amino acid residues that could be localized at the plasma membrane when expressed in tobacco leaf protoplasts.MdSUT2.1 was highly expressed in fruit and was positively correlated with sucrose accumulation during apple fruit development.Moreover,complementary growth assays in a yeast mutant validated the sucrose transport activity of MdSUT2.1.MdSUT2.1 overexpression in apples and tomatoes resulted in significant increases in sucrose,fructose,and glucose contents compared to the wild type(WT).Further analysis revealed that the expression levels of sugar metabolism-and transport-related genes SUSYs,NINVs,FRKs,HXKs,and TSTs increased in apples and tomatoes with MdSUT2.1 overexpression compared to WT.Finally,unlike the tonoplast sugar transporters MdTST1 and MdTST2,the promoter of MdSUT2.1 was not induced by exogenous sugars.These findings provide valuable insights into the molecular mechanism underlying sugar accumulation in apples.

Effects of Salinity Stress on the Levels of Covalently and Noncovalently Conjugated Polyamines in Plasma Membrane and Tonoplast Isolated from Barley Seedlings

When the 7_d old barley ( Hordeum vulgare L.) seedlings were treated with different concentrations of NaCl for 3 d, the levels of the noncovalently conjugated polyamines (PAs) in the plasma membrane and tonoplast vesicles and the covalently conjugated PAs in the membrane proteins were promoted by NaCl of low concentrations and suppressed by NaCl of high concentrations. Among the noncovalently conjugated PAs in the vesicles, spermidine (Spd) level was the most abundant, while putrescine (Put) content was predominant among the covalently conjugated PAs, accounted for 40%-70%, 35%-60%, respectively. In addition, the TLC (thin_layer chromatography) profiles of the benzoylated PAs presented an unknown polyamine with Rf =0.92 (X 0.92 ), which conjugated covalently and noncovalently in root tonoplast and its content changed as well as Spd with NaCl treatment. The total PA contents in the roots were higher than that in the leaves, and the types and contents of covalently and noncovalently conjugated PAs in the tonoplast were higher than those in the plasma membrane. The results showed that the above two PAs associated with the membrane might be essential in salt adaption of cells and the maintenance of membrane function.

Effect of Sound Stimulation on the Lipid Physical States and Metabolism of Plasma Membrane from Chrysanthemum Callus

Plasma membrane vesicles of chrysanthemum ( Dendranthema morifolium (Ramat.) Tzvel.) callus was purified by sucrose gradient centrifugation to investigate the influence of sound stimulation on the lipid physical states and metabolism of plasma membrane. The results showed that sound stimulation decreased the content of phosphodiesters and the fluorescent intensity of DPH, but increased the light scattering value of the membrane, the fluorescent intensity of MC540 and the content of phosphomonoesters, indicating that the vesicles got looser, the charge density and hydrophobicity of membrane surface decreased under sound stimulation of some strength and frequency. However, the membrane fluidity increased under the condition. Meanwhile, the anabolism of membrane lipid increased and the catabolism decreased. It can be seen that the physical state and metabolism of membrane lipid is sensitive to sound stimulation.

Activation of Plasma Membrane NADPH Oxidase and Generation of H_2O_2 Mediate the Induction of PAL Activity and Saponin Synthesis byEndogenous Elicitor in Suspension-Cultured Cells of Panax ginseng

Endogenous elicitor, termed cellulase-degraded cell wall (CDW), was prepared from the cell wall of suspension-cultured ginseng (Panax ginseng C.A. Meyer) cells via cellulase degradation. CDW activated the NADPH oxidase activity of isolated plasma membranes and stimulated in vivo H2O2 generation in ginseng cell suspensions. CDW also increased the activity of phenylalanine ammonia lyase (PAL), expression of a P. ginseng squalene epoxidase (sqe) gene and saponin synthesis. NADPH oxidase inhibitors inhibited both in vitro NADPH oxidase activity and in vivo H2O2 generation. Induction of PAL activity, saponin synthesis and sqe gene expression were all inhibited by such inhibitor treatments and reduced by incubation with catalase and HA scavengers. These data indicate that activation of NADPH oxidase and generation of H2O2 are essential signalling events mediating defence responses induced by the endogenous elicitor(s) present in CDW.

Influence of K + on the Coupling Between ATP Hydrolysis and Proton Transport by the Plasma Membrane H +_ATPase from Soybean Hypocotyls

The plasma membrane vesicles were purified from soybean (Glycine max L.) hypocotyls by two_phase partitioning methods. The stimulatory effects of K + on the coupling between ATP hydrolysis and proton transport by the plasma membrane H +_ATPase were studied. The results showed that the proton transport activity was increased by 850% in the presence of 100 mmol/L KCl, while ATP hydrolytic activity was only increased by 28.2%. Kinetic studies showed that K m of ATP hydrolysis decreased from 1.14 to 0.7 mmol/L, while V max of ATP hydrolysis increased from 285.7 to 344.8 nmol Pi·mg -1 protein·min -1 in the presence of KCl. Experiments showed that the optimum pH was 6.5 and 6.0 in the presence and absence of KCl, respectively. Further studies revealed that K + could promote the inhibitory effects of hydroxylamines and vanadates on the ATP hydrolytic activity. The above results suggested that K + could regulate the coupling between ATP hydrolysis and proton transport of the plasma membrane H +_ATPase through modulating the structure and function of the kinase and phosphatase domains of the plasma membrane H +_ATPase.

Isolation of Plasma and Thylakoid Membranes from the Heterocystous Cyanobacterium Anabaena sp. PCC 7120

利用水溶性多聚体双相法分离蓝细菌Anabaenasp .PCC 712 0质膜和类囊体膜两种膜系统。吸收光谱分析表明 ,质膜相和类囊体膜相的主要色素分别为类胡萝卜素和叶绿素。SDS_凝胶电泳显示这两种膜系统蛋白组成有很大差别。这种分离方法容易操作 ,对研究蓝细菌的膜蛋白和膜脂非常有用。

Effect of Lysophosphatidylcholine on ATP and ρ-Nitrophenyl Phosphate Hydrolysis by the Plasma Membrane H^+-ATPase from Soybean Hypocotyls

The stimulatory effect of lysophosphatidylcholine (lyso_PC) on ATP and ρ_nitrophenyl phosphate (PNPP) hydrolysis by the plasma membrane H +_ATPase from soybean (Glycine max (L.) Merr.) hypocotyls was studied. Results showed that lyso_PC stimulated the hydrolysis of ATP; ATP hydrolysis was enhanced dramatically when lyso_PC was within 0-0.03%, and increased slightly when lyso_PC was higher than 0.03%. At the concentration of 0.03%, lyso_PC stimulated ATP hydrolysis by 80.5%. Kinetics analysis showed that V max increased from 0.46 μmol P i·mg -1 protein·min -1 to 0.87 μmol P i·mg -1 protein·min -1 while K m increased from 0.88 mmol/L to 1.15 mmol/L under lyso_PC treatment. The optimum pH of ATP hydrolysis was shifted from 6.5 to 7.0 . Moreover, it was found lyso_PC enhanced the inhibition of ATP hydrolysis by hydroxylamine. In the presence of 200 mmol/L hydroxylamine, ATP hydrolysis was inhibited by 74.4%, while it was inhibited by 84.4% when treated with lyso_PC. However, PNPP hydrolysis and the inhibitory effect of vanadate were not affected by lyso_PC. The above results indicated that the kinase domain might be an action site or regulatory region of the C_terminal autoinhibitory domain in the plant plasma membrane H +_ATPase.

Platelet rich fibrin is not a barrier membrane!Or is it?

Platelet-rich fibrin(PRF)is widely used in dentistry and other fields of medicine,and its use has become popular in dental implantology.In several published studies,PRF has been used as a barrier membrane.A barrier membrane is a sheet of a certain material that acts as a biological and mechanical barrier against the invasion of cells that are not involved in bone formation,such as epithelial cells.Among the basic requirements of a'barrier membrane,occlusivity,stiffness,and space maintenance are the criteria that PRF primarily lacks;therefore,it does not fall under the category of barrier membranes.However,there is evidence that PRF membranes are useful in significantly improving wound healing.Does the PRF membrane act as a barrier?Should we think of adding or subtracting some points from the ideal requirements of a barrier membrane,or should we coin a new term or concept for PRF that will incorporate some features of a barrier membrane and be a combination of tissue engineering and biotechnology?This review is aimed at answering the basic question of whether the PRF membrane should be considered a barrier membrane or whether it is something more beyond the boundaries of a barrier membrane.

Effects of salinity on activities of H^+-ATPase, H^+-PPase and membrane lipid composition in plasma membrane and tonoplast vesicles isolated from soybean(Glycine max L.) seedlings

The effects of NaCl stress on the H +-ATPase, H +-PPase activity and lipid composition of plasma membrane(PM) and tonoplast(TP) vesicles isolated from roots and leaves of two soybean cultivars(Glycine max L.) differing in salt tolerance(Wenfeng7, salt-tolerant; Union, salt-sensitive) were investigated. When Wenfeng7 was treated with 0.3%(W/V) NaCl for 3 d, the H +-ATPase activities in PM and TP from roots and leaves exhibited a reduction and an enhancement, respectively. The H +-PPase activity in TP from roots also increased. Similar effects were not observed in roots of Union. In addition, the increases of phospholipid content and ratios of phospholipid to galactolipid in PM and TP from roots and leaves of Wenfeng7 may also change membrane permeability and hence affect salt tolerance.

Changes of plasma membrane ATPase activity, membrane potential and transmembrane proton gradient in Kandelia candel and Avicennia marina seedlings with various salinities

The salt-secreting mangrove, Avicennia marina, and non-salt-secreting mangrove, Kandelia candel were cultivated in sand with various salinities(0‰, 10‰, 20‰, 30‰, 40‰) for 60 d. Plasma membrane vesicles of high-purity in leaves and roots of A.marina and K. candel seedlings were obtained by two-phase partitioning. The function of the plasma membranes, the activity of ATPase, membrane potential and transmembrane proton gradient, at various salinities were investigated. The results showed that within a certain range of salinity(A. marina and roots of K. candel: 0—30‰; leaves of K.candel: 0—20‰), the activity of ATPase increased with increasing salinity, while high salinity(above 30‰ or 20‰) inhibited ATPase activity. In comparison with A. marina, K. candel appeared to be more sensitive to salinity. The dynamics of membrane potential and transmembrane proton gradient in leaves and roots of A. marina and K. candel seedlings were similar to that of ATPase. When treated directly by NaCl all the indexes were inhibited markedly: there was a little increase within 0—10‰(K. candel) or 0—20‰(A. marina) followed by sharp declining. It indicated that the structure and function of plasma membrane was damaged severely.

Water relations and an expression analysis of plasma membrane intrinsic proteins in sensitive and tolerant rice during chilling and recovery

A symptom of chilling injury is development of water deficit in shoots, resulting from an imbalance of water transport and transpiration. In this work, two rice varieties （Oryza sativa L. var. Wasetoitsu and Somewake） seedlings were chilled at 7 ℃, followed by recovery at 28 ℃. Based on the growth phenotype and electrolyte leakage tests, Somewake was shown to be a chilling-tolerant variety, and Wasetoitsu a chilling-sensitive one. The chilling stress reduced markedly the relative water content （RWC） of leaves, accumulative transpiration and osmotic root hydraulic conductivity （Lp） in both varieties. But when retumed to 28 ℃, the water relation balance of Somewake recovered better. The mRNA expression profile of all the 11 plasma membrane intrinsic proteins （PIPs）, a subgroup of aquaporins, was subsequently determined by real-time reverse transcription （RT）-PCR with TaqMan-minor grove binder （MGB） probes derived from rice var. Nipponbare during chilling treatment and recovery. Most of the PIP genes was down-regulated at the low temperature, and recovered at the warm temperature. The relative expression of some PIPs in both Somewake and Wasetoitsu decreased in parallel during the chilling. However during the recovery, the relative expression of OsPIP1;1, OsPIP2;1, OsPIP2;7 in shoots and OsPIP1：1, OsPIP2：1 in roots were significantly higher in Somewake than Wasetoitsu. This supports the role of PIPs in re-establishing water balance after chilling conditions. We discuss the diversified roles played by members of the aquaporin PIP subfamily in plant chilling tolerance depending on aquaporin isoforms, plant tissue and the stage of chilling duration.

Involvement of Plasma Membrane Ca^(2+)/H^+ Antiporter in Cd^(2+) Tolerance

Cation exchangers （CAXs） belong to the cation/Ca2＋exchanger superfamily which have been extensively investigated in plant tonoplasts over the last decade. Recently, the roles of CAXs involved in heavy metal accumulation and tolerance in plants have been studied for phytoremediation and food security. In this mini review, we summarize the roles of the Ca2＋/H＋ antiporter in Ca2＋ signal transduction, maintaining ion homeostasis and sequestering heavy metals into the vacuole. Moreover, we present a possible role of the plasma membrane Ca2＋/H＋ antiporter in heavy metal detoxification.

Surface Modification of Polypropylene Microporous Membrane by Atmospheric-pressure Plasma Induced N-vinyl-2-pyrrolidone Graft Polymerization

Membrane surfaces modified with poly（N-vinyl-2-pyrrolidone） （PNVP） can be endowed with hydrophilicity, biocompatibility and functionality. In this work, atmospheric pressure dielectric barrier discharge plasma graft polymerization of N-vinyl-2-pyrrolidone （NVP） onto polypropylene （PP） microporous membrane surface was studied. The experimental results reveal that plasma treatment conditions, such as discharge power, treatment time and adsorbed NVP amount, have remarkable effects on the grafting degree of NVP. Structural and morphological changes on the membrane surfaces were characterized by attenuated total reflection-Fourier transform infrared spectroscopy （FT-IR/ATR）, X-ray photoelectron spectroscope （XPS） and field emission scanning electron microscopy （FE-SEM）. Water contact angles of the membrane surfaces were also measured by the sessile drop method. Water contact angles on the membrane surfaces decrease with the increase of NVP grafting degree, which indicates an enhanced hydrophilicity for the modified membranes. The effects of grafting degrees on pure water fluxes were also measured. It is shown that pure water fluxes increase with grafting degree firstly and then decrease adversely. Finally, filtration of bovine serum albumin （BSA） solution and platelets adhesion of the PNVP modified membranes show good protein resistance and potential biocompatibility due to the enhancement of surface hydrophilicity.

Surface Modification of Polyvinylidene Fluoride (PVDF) Membranes by Low-Temperature Plasma with Grafting Styrene

In order to control the surface pore sizes of polyvinylidene fluoride membranes and their distribution, low temperature plasma-induced grafting modifications of PVDF were studied to prepare hydrophobe membranes. By argon （Ar） treating and subsequent grafting reaction, a hydrophobe monomer, styrene, was introduced into the PVDF membrane. Fourier transform infrared attenuated total reflection （FTIR-ATR） was utilized to characterize the chemical and physical changes in the Ar plasma modified membrane. The surface modifications of PVDF membranes were investigated by using scanning electron microscopy （SEM）, atomic force microscopy （AFM） and differential scanning calorimeter （DSC）. The water permeability and the solute rejection were measured by PVDF membrane modified in different graft conditions. Results demonstrated that the pores in the modified membranes get smaller and the distribution of pores gets narrowed with the increase in grafting reaction duration. Longer graft time caused the water flux of PVDF membrane to decrease from 578 kg/（m^2· h） to 23 kg/（m^2· h） and the solute rejection to increase from 73% to 92%.

Argon Plasma-Induced Graft Polymerization of PEGMA on Chitosan Membrane Surface for Cell Adhesion Improvement

For its biocompatibility and biodegradability, chitosan has had considerable atten- tion for biomedical applications in recent years. In this paper, polymerization of poly （ethylene glycol） methyl ether methacrylate （PEGMA） was grafted onto chitosan membrane surface through argon plasma-induced graft polymerization. The surface properties after modification were characterized by contact angle measurement, X-ray photoelectron spectroscopy （XPS） and atomic force microscopy （AFM）, respectively. The results indicated that PEGMA can be grafted successfully onto chitosan membrane surface. The surface hydrophilicity and free energy were improved and the surface roughness increased after modification. The adhesion of a human corneal epithelial cell （HCEC） on chitosan membrane surface was enhanced due to improvement of surface free energy and roughness.