An empirical study on the dynamic effect of regional industrial carbon transfer in China

The dynamic trend of regional industrial carbon transfer along with industrial transfers in China is currently a hot topic. To explore this problem, the gravity model has been used to study the spatial distribution of industrial transfer and industrial carbon transfer. The results indicate that both barycenters are moving westward. Based on the STIRPAT model, a system-GMM model was then constructed that introduced the industrial transfer factor and its square to explore temporal changes in regional industrial carbon transfer in the course of industrial transfer. The estimated results revealed that the relationship between industrial transfer and industrial carbon transfer displays an inverted U-shaped pattern. For every 1% increase in industrial transfer, there was a 0.327% increase in industrial carbon transfer before the turning point, but industrial carbon transfer decreased by 0.07% when it passed the “peak”. Because no province had surpassed the turning point, carbon transfer during industrial transfer in China is currently in the growth phase. Moreover, real GDP per capita, industrial structure, and industrial carbon emission intensity promoted carbon emissions reduction in the course of industrial transfer.     

转移缓冲液对蛋白质印迹的影响

利用三种转移缓冲液,分别以半干和湿转法,检测癌基因产物Bcl-2, 并获得不同强度的印迹结果.不含SDS的转移缓冲液转移效果明显优于含SDS的转移缓冲液,且SDS含量越高印迹带越弱;此外,半干转移与湿转相比,可大大缩短转移时间,但转移效果不及湿转理想且稳定性较差.     

Immunoprecipitation of lipid transfer protein activity by an antibody against human plasma lipid transfer protein-I

Two lipid transfer proteins, designated lipid transfer protein-I (Mr 69 000) and lipid transfer protein-II (Mr 55 000), each of which facilitates the transfer of radiolabelled cholesteryl ester, triacylglycerol and phosphatidylcholine between plasma lipoproteins, were purified from human plasma. Immunoglobulin G was prepared from goat antiserum to human lipid transfer protein-I (i.e., anti-human LTP-I IgG). The progressive addition of anti-human LTP-I IgG to buffered solutions containing either a highly purified mixture of human lipid transfer protein-I and lipid transfer protein-II, or highly purified rabbit lipid transfer protein (Abbey, M., Calvert, G.D. and Barter, P.J. (1984) Biochim. Biophys. Acta 793, 471-480) resulted in specific immunoprecipitation and the removal of increasing amounts, up to 100%, of cholesteryl ester, triacylglycerol and phosphatidylcholine transfer activities. However, similar precipitation studies on human and rabbit lipoprotein-free plasma resulted in the progressive removal of all cholesteryl ester and triacylglycerol transfer activities but only 30% (human) or 20% (rabbit) of phosphatidylcholine transfer activity. In all cases more anti-human LTP-I IgG was required to precipitate rabbit lipid transfer activity than human lipid transfer activity. These results suggest that lipid transfer protein-I and lipid transfer protein-II have antigenic sites in common, allowing precipitation of both proteins by specific antibody to lipid transfer protein-I. Most plasma phosphatidylcholine transfer activity is mediated by a protein (or proteins) other than lipid transfer protein-I and lipid transfer protein-II. In lipoprotein-free plasma all cholesteryl ester and triacylglycerol transfer activity, and some phosphatidylcholine transfer activity, is mediated by lipid transfer protein-I (or lipid transfer protein-I and an antigenically similar protein, lipid transfer protein-II.     

Specificity of the glycolipid transfer protein from pig brain

Lipid specificity has been studied in the lipid transfer reaction facilitated by the glycolipid transfer protein from pig brain. The lipid transfer was measured by determining the transfer of a radioisotopically labeled lipid from donor liposomes to either acceptor liposomes or mitochondria. Whenever possible, the liposomes contained 1 mol % of the lipid whose transfer was under study. The transfer protein accelerates the transfer of glucosylceramide, galactosylceramide (GalCer), lactosylceramide (LacCer), galactosylceramide 3-sulfate, globotriaosylceramide, LacCer sulfate, sialosyl-LacCer, globotetraosylceramide, and globopentaosylceramide. An inverse relationship is found between the length of sugar chains in glycosphingolipids and the transfer rates. In addition to the glycosphingolipids, the transfer protein facilitates the transfer of galactosyldiacylglycerol, digalactosyldiacylglycerol, glucosyldiacylglycerol, and diglucosyldiacylglycerol. The protein does not facilitate the transfer of dimannosyldiacylglycerol. The transfer of periodate-oxidized and subsequently reduced derivatives of GalCer and LacCer is facilitated by the transfer protein. The derivatives of GalCer are transferred at lower rates than GalCer, whereas the derivatives of LacCer are transferred at higher rates than LacCer. The transfer protein does not facilitate the transfer of phosphatidylcholine, phosphatidylinositol, cholesterol, or cholesteryloleate. These results suggest that the glycolipid transfer protein from pig brain has specificity to hydroxyl groups present in the sugar residue directly linked to either ceramide or diacylglycerol. The presence of glucose or galactose linked to these hydrophobic moieties makes the glycolipid transferable by the protein.     

Mechanisms for regulating electron transfer in multi-centre redox proteins.

Protein-mediated electron transfer is a key process in nature. Many of the proteins involved in such electron transfers are complex and contain a number of redox-active cofactors. The very complexity of these multi-centre redox proteins has made it difficult to fully understand the various electron transfer events they catalyse. This is sometimes because the electron transfer steps themselves are gated or coupled to other processes such as proton transfer. However, with the molecular structures of many of these proteins now available it is possible to probe these electron transfer reactions at the molecular level. It is becoming apparent that many of these multi-centre redox proteins have rather subtle and elegant ways for regulating electron transfer. The purpose of this article is to illustrate how nature has used different approaches to control electron transfer in a number of different systems. Illustrative examples include: thermodynamic control of electron transfer in flavocytochromes b(2) and P450 BM3; a novel control mechanism involving calmodulin-binding-dependent electron transfer in neuronal nitric oxide synthase; the probable gating of electron transfer by ATP hydrolysis in nitrogenase; conformational gating of electron transfer in cytochrome cd(1); the regulation of electron transfer by protein dynamics in the cytochrome bc(1) complex; and finally the coupling of electron transfer to proton transfer in cytochrome c oxidase.     

Stimulated and co-operative electron transfer in energy conversion and catalysis.

A new mechanism of electron transfer, stimulated electron transfer, is postulated, in which an electronic feedback is drastically increasing both the rate of electron transfer and the propagation of free energy along electron transferring molecular pathways. In principle, the idea of pushing a system far from equilibrium to achieve a high reaction rate and co-operative phenomena is applied to molecular electron transfer. The effect is calculated from a semiclassical kinetic model of a chain redox reaction with autocatalytic feedback on individual rate constants, where the steps have subsequently been minimized to obtain a continuous electron transfer pathway with electronic feedback. The influence of inhomogeneities and asymmetries in the electron transfer path and of vectorial components (electrical field, gradient of redox potential) are discussed as well as the acceleration of individual and multiple electron transfer as a function of feedback. Examples of autocatalytic feedback are provided including mechanisms involving electron transfer proteins and multi-centre electron transfer catalysts. Such a phenomenon can be described for molecular and interfacial electron transfer in analogy to stimulated and coherent light emission. The results suggest that autocatalytic or stimulated electron transfer may be a key to the understanding of efficient electron transfer and co-operative multi-electron transfer catalysis in biology and a challenge for fuel production mechanisms in artificial photosynthesis and fuel cycles.     

Interaction of plasma-derived lipid transfer protein with macrophages in culture

This study investigates the ability of human plasma-derived lipid transfer protein to facilitate lipid transfer to and from intact viable cells in culture. Mouse peritoneal macrophages or J774 macrophages were preincubated with acetylated low density lipoprotein and [3H]oleate/albumin to promote the intracellular synthesis and accumulation of cholesteryl [3H]oleate and 3H-labeled triglyceride. The addition of partially purified lipid transfer protein to cultures of lipid-loaded macrophages resulted in a time and concentration-dependent transfer of radiolabeled cholesteryl ester and triglyceride from macrophages to the medium. At 48 hr, lipid transfer protein facilitated the net transfer of 16 and 11% of cellular cholesteryl ester and triglyceride radioactivity, respectively, to the medium; transfer in the absence of the lipid transfer protein was less than 2%. The transfer of cholesteryl ester radioactivity was accompanied by a similar decrease in cellular cholesteryl ester mass indicating a net transfer event. Lipid transfer from cells was not dependent on the presence of a lipoprotein acceptor in the medium; however, low and high density lipoproteins present at 200 micrograms cholesterol/ml did significantly stimulate the transfer protein-facilitated efflux of these lipids. Lipid transfer protein did not appear capable of transferring radiolabeled lipid from low density or high density lipoprotein to macrophages. Radiolabeled cholesteryl ester and triglyceride transferred from cells to the medium by lipid transfer protein were associated with large molecular weight (greater than 2 x 10(6)) components in the medium with an average density greater than 1.21 g/ml; these lipids were not associated with lipid transfer protein itself. However, these radiolabeled lipids were readily incorporated into low or high density lipoproteins when these lipoproteins were added to the medium either during or after its incubation with cells. It is concluded that lipid transfer protein can facilitate the net efflux of cholesteryl esters from intact, living macrophages. These studies suggest a novel and potentially antiatherogenic role for lipid transfer protein.     

Plasmid Specificity of The Origin of Transfer of Sex Factor F

The ability of F-like plasmids to promote transfer from the F origin of transfer was determined. Chromosome transfer was measured from plasmid derivatives of RecA(-) Hfr deletion strains which had lost all the F transfer genes but which in some cases retained, and in others had also lost, the origin sequence. ColV2 and ColVBtrp could initiate transfer from the F origin, but R100-1, R1-19, and R538-1 drd could not. These results can be correlated with the plasmid specificity of the traI components of the different plasmid transfer systems, supporting the hypothesis that the origin of transfer is the site of action of the traI product. Most F-like plasmids, including R1-19 and R538-1 drd, could transfer ColE1, consistent with previous findings that the (plasmid-specific) traI product is not necessary for ColE1 transfer by Flac; ColE1 transfer may be initiated by a ColE1-or host-determined product. R100-1 and R136fin(-) could not transfer ColE1 efficiently, apparently because of differences residing in their pilus-forming genes.     

Plasma lipid transfer proteins

PURPOSE OF REVIEW: Plasma cholesteryl ester transfer protein and phospholipid transfer protein are involved in lipoprotein metabolism. Conceivably, manipulation of either transfer protein could impact atherosclerosis and other lipid-driven diseases. RECENT FINDINGS: Cholesteryl ester transfer protein mediates direct HDL cholesteryl ester delivery to the liver cells; adipose tissue-specific overexpression of cholesteryl ester transfer protein in mice reduces the plasma HDL cholesterol concentration and adipocyte size; cholesteryl ester transfer protein TaqIB polymorphism is associated with HDL cholesterol plasma levels and the risk of coronary heart disease. In apolipoprotein B transgenic mice, phospholipid transfer protein deficiency enhances reactive oxygen species-dependent degradation of newly synthesized apolipoprotein B via a post-endoplasmic reticulum process, as well as improving the antiinflammatory properties of HDL in mice. Activity of this transfer protein in cerebrospinal fluid of patients with Alzheimer's disease is profoundly decreased and exogenous phospholipid transfer protein induces apolipoprotein E secretion by primary human astrocytes in vitro. SUMMARY: Understanding the relationship between lipid transfer proteins and lipoprotein metabolism is expected to be an important frontier in the search for a therapy for atherosclerosis.     

Charged membrane surfaces impede the protein-mediated transfer of glycosphingolipids between phospholipid bilayers

A lipid transfer protein that facilitates the transfer of glycolipids between donor and acceptor membranes has been investigated using a fluorescence resonance energy transfer assay. The glycolipid transfer protein (23-24 kDa, pI 9.0) catalyzes the high specificity transfer of lipids that have sugars beta-linked to either a ceramide or a diacylglycerol backbone, such as simple glycolipids and gangliosides, but not the transfer of phospholipids, cholesterol, or cholesterol esters. In this study, we examined the effect of different charged lipids on the rate of transfer of anthrylvinyl-labeled galactosylceramide (1 mol %) from a donor to acceptor vesicle population at neutral pH. Compared to neutral donor vesicle membranes, introduction of negatively charged lipid at 5 or 10 mol % into the donor vesicles significantly decreased the transfer rate. Introduction of the same amount of negative charge into the acceptor vesicle membrane did not impede the transfer rate as effectively. Also, positive charge in the donor vesicle membrane was not as effective at slowing the transfer rate as was negative charge in the donor vesicle. Increasing the ionic strength of the buffer with NaCl significantly reversed the charge effects. At neutral pH, the transfer protein (pI congruent with 9.0) is expected to be positively charged, which may promote association with the negatively charged donor membrane. Based on these and other experiments, we conclude that the transfer process follows first-order kinetics and that the off-rate of the transfer protein from the donor vesicle surface is the rate-limiting step in the transfer process.     

Transfer factors: identification of conserved sequences in transfer factor molecules

BACKGROUND: Transfer factors are small proteins that "transfer" the ability to express cell-mediated immunity from immune donors to non-immune recipients. We developed a process for purifying specific transfer factors to apparent homogeneity. This allowed us to separate individual transfer factors from mixtures containing several transfer factors and to demonstrate the antigen-specificity of transfer factors. Transfer factors have been shown to be an effective means for correction of deficient cellular immunity in patients with opportunistic infections, such as candidiasis or recurrent Herpes simplex and to provide prophylactic immunity against varicella-zoster in patients with acute leukemia. MATERIALS AND METHODS: Transfer factors of bovine and murine origin were purified by affinity chromatography and high performance liquid chromatography. Cyanogen bromide digests were sequenced. The properties of an apparently conserved sequence on expression of delayed-type hypersensitivity by transfer factor recipients were assessed. RESULTS: A novel amino acid sequence, LLYAQDL/VEDN, was identified in each of seven transfer factor preparations. These peptides would not transfer expression of delayed-type hypersensitivity to recipients, which indicates that they are not sufficient for expression of the specificity or immunological properties of native transfer factors. However, administration of the peptides to recipients of native transfer factors blocked expression of delayed-type hypersensitivity by the recipients. The peptides were not immunosuppressive. CONCLUSIONS: These findings suggest that the peptides may represent the portion of transfer factors that binds to the "target cells" for transfer factors. Identification of these cells will be helpful in defining the mechanisms of action of transfer factors.     

Net mass transfer of galactosylceramide facilitated by glycolipid transfer protein from pig brain: a monolayer study

A net mass transfer of galactosylceramide (GalCer) and galactosyldiacylglycerol (GalDG) is catalyzed by the glycolipid transfer protein from pig brain. GalCer and GalDG are transferred from a monolayer to phosphatidylcholine vesicles in the subphase or from a glycolipid monolayer to a phosphatidylcholine monolayer. No transfer of phosphatidylcholine is measured under these conditions. It is found that the glycolipid transfer protein functions as a carrier and that glycolipid is bound to less than 50% of the transfer protein. The presence of lipid-free proteins fits with the proposed mechanism of net mass transfer. The glycolipid transfer is influenced by the fluidity of the lipid interface and by the matrix lipid of the interface. GalCer transfer is stimulated in the presence of GalDG.     

Oxygen transfer properties of bubbles in animal cell culture media

Oxygen transfer rates were determined in a bubble aerated animal cell bioreactor. It was found that the oxygen transfer rates increased in the following order: large bubbles ( approximately 5 mm diameter) < intermediate bubbles ( approximately 1 mm diameter) < micron-sized bubbles ( approximately 100 mum diameter). Under certain conditions, the micron-sized bubbles were capable of achieving oxygen transfer rate up to 100 h(-1), a 10-20-fold higher transfer rate than the large bubbles. The effects of medium composition on oxygen transfer rates were different for the three ranges of bubbles studied. For the large bubbles, oxygen transfer rates decreased with increasing medium complexity. The lowest oxygen transfer rate was found in new-born calf serum (NBCS) and/or Pluronic F-68 supplemented media. For the intermediate and micron-sized bubbles, supplementation with NBCS into the culture media resulted in decreased oxygen transfer rate. However, further supplementation with Pluronic F-68 enhanced oxygen transfer rate greatly for both types of bubbles. The highest oxygen transfer rate was found for micron-sized bubbles in Pluronic F-68 supplemented media containing antifoam agent and NBCS.     

Effects of inhibition of the B subunit of DNA gyrase on conjugation in Escherichia coli.

Antagonism of the DNA gyrase B subunit in the donor bacterium by coumermycin or thermal inactivation inhibited transfer of plasmid R64drd-11. Coumermycin also inhibited Hfr transfer, with kinetics after drug removal suggesting that transfer resumed from the point of inhibition, in contrast to inhibition with nalidixic acid, after which transfer reinitiated from the origin of transfer.     

Laser-flash photolysis indicates that internal electron transfer is triggered by proton uptake by Alcaligenes xylosoxidans copper-dependent nitrite reductase

Enzyme-catalysed electron transfer reactions are often controlled by protein motions and coupled to chemical change such as proton transfer. We have investigated the nature of this control in the blue copper-dependent nitrite reductase from Alcaligenes xylosoxidans (AxNiR). Inter-Cu electron transfer from the T1Cu site to the T2Cu catalytic site in AxNiR occurs via a proton-coupled electron transfer mechanism. Here we have studied the kinetics of both electron and proton transfer independently using laser-flash photolysis for native AxNiR and its proton-channel mutant N90S. In native AxNiR, both inter-Cu electron transfer and proton transfer exhibit similar rates, and show an unusual dependence on the nitrite concentration. An initial decrease in the observed rates at low nitrite concentrations is followed by an increase in the observed rates at high nitrite concentrations (> 5 mm). In N90S, in which the T1Cu reduction potential is elevated by 60 mV, no inter-Cu electron transfer or proton transfer was observed in the absence of nitrite. Only in the presence of nitrite were both processes detected, with similar [nitrite] dependence, but the nitrite dependence was different compared with native enzyme. The substrate dependence in N90S was similar to that observed in steady-state assays, suggesting that this substitution resulted in proton-coupled electron transfer becoming rate-limiting. A pH perturbation experiment with native AxNiR revealed that protonation triggers inter-Cu electron transfer and generation of NO. Our results show a strong coupling of inter-Cu electron transfer and proton transfer for both native AxNiR and N90S, and provide novel insights into the controlled delivery of electrons and protons to the substrate-utilization T2Cu active site of AxNiR.     

基于直接接触的微生物胞外电子传递

微生物电子传递在微生物的代谢繁殖和物质的生物地球化学循环中发挥着关键作用。其中基于直接接触的微生物胞外电子传递(Direct extracellular electron transfer,DEET)已成为微生物学、地球化学和生物物理学等学科共同关注的焦点,并在近几年取得了一系列重要发现和理论突破,包括微生物纳米导线、电缆细菌、微生物种间DEET等。伴随着这些新进展,更多的问题也需要研究者们在进一步的研究中解决,包括DEET的分子机制及其相关功能微生物种群等。不同学科理论和技术的交叉是进一步揭示DEET过程的关键。     

Transfer of cholesteryl esters and phospholipids as well as net deposition by microsomal triglyceride transfer protein

Microsomal triglyceride transfer protein (MTP) activity is classically measured using radioactive lipids. We described a simple fluorescence assay to measure its triacylglycerol (TAG) transfer activity. Here, we describe fluorescence-based methods to measure the transfer of phospholipids (PLs) and cholesteryl esters (CEs) by MTP. Both transfer activities increased with time and MTP amounts and were inhibited to different extents by an MTP antagonist, BMS197636. We also describe a method to measure the net deposition of fluorescent lipids in acceptor vesicles. In this procedure, negatively charged donor vesicles are incubated with MTP and acceptor vesicles, and lipids transferred to acceptors are quantified after the removal of donor vesicles and MTP by the addition of DE52. Lipid deposition in acceptor vesicles was dependent on time and MTP. Using these methods, TAG transfer activity was the most robust activity present in purified MTP; CE and PL transfer activities were 60-71% and 5-13% of the TAG transfer activity, respectively. The method to determine lipid transfer is recommended for routine MTP activity measurements for its simplicity. These methods may help identify specific inhibitors for individual lipid transfer activities, in characterizing different domains involved in transfer, and in the isolation of mutants that bind but cannot transfer lipids.     

Second Chances: Investigating Athletes’ Experiences of Talent Transfer

Talent transfer initiatives seek to transfer talented, mature individuals from one sport to another. Unfortunately talent transfer initiatives seem to lack an evidence-based direction and a rigorous exploration of the mechanisms underpinning the approach. The purpose of this exploratory study was to identify the factors which successfully transferring athletes cite as facilitative of talent transfer. In contrast to the anthropometric and performance variables that underpin current talent transfer initiatives, participants identified a range of psycho-behavioral and environmental factors as key to successful transfer. We argue that further research into the mechanisms of talent transfer is needed in order to provide a strong evidence base for the methodologies employed in these initiatives.     

Characterization and cytogenetic analysis of Japanese Black calves produced by nuclear transfer

To confirm the normality of the Japanese Black calves produced by nuclear transfer, we examined the properties of such calves at parturition and analyzed their karyotypes. Thirty Japanese Black calves were produced by nuclear transfer; 3 of these calves (10.0%) required assisted delivery while 1 calf (3.3%) died soon after birth. Average birth weight was 31.0 +/- 1.8 kg and gestation period was 286.4 +/- 1.0 d (mean +/- SEM). None of the nuclear transfer calves showed external malformations. Within sets of cloned nuclear transfer calves, which were genetically identical, birth weights varied by up to 20.5 kg. Among singleton Japanese Black calves, the mean birth weight of nuclear transfer calves was significantly greater (P < 0.05) than that of calves produced by in vivo-derived embryo transfer. Cytogenetic analysis of 23 Japanese Black nuclear transfer calves revealed the presence of 2N 4N mosaicism in 21 of the nuclear transfer calves. The frequency of occurrence of tetraploidy was unrelated to birth weight. Endoreduplication was observed in 1 Japanese Black nuclear transfer calf, and the frequency of occurrence of the endoreduplication in this calf was 0.5% (1/209). We conclude that there was no external malformation or chromosomal aneuploidy in Japanese Black nuclear transfer calves, but the mean birth weight of nuclear transfer calves was heavier than that of in vivo-derived embryo transfer calves in both sexes, and a variation of birth weight within sets of nuclear transfer calves cloned from the same embryo was recognized.     

Estrogen treatment increases phospholipid transfer activities in chicken liver

The effect of subcutaneous beta-estradiol injection on liver phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol transfer activity of immature chicken has been determined. The estrogen administration significantly enhanced the transfer activity of both phosphatidylcholine (100%), phosphatidylethanolamine (160%), and phosphatidylinositol (150%). In vivo experiments revealed that the hormone-induced changes in liver lipid transfer activity were sensitive to a protein synthesis inhibitor, cycloheximide. A partial characterization of liver protein transfer on Sephacryl S-200 showed that multiple transfer proteins are involved in the beta-estradiol effect. This is the first time that hormonal modulation of phospholipid transfer activities is described, and the results suggest that the hepatic phospholipid transfer activities might be involved in the biosynthesis of plasma lipoproteins in vivo.