Cloning of the Lentinula edodes B mating-type locus and identification of the genetic structure controlling B mating

During the life cycle of heterothallic tetrapolar Agaricomycetes such as Lentinula edodes (Berk.) Pegler, the mating type system, composed of unlinked A and B loci, plays a vital role in controlling sexual development and resulting formation of the fruit body. L. edodes is produced worldwide for consumption and medicinal purposes, and understanding its sexual development is therefore of great importance. A considerable amount of mating type factors has been indicated over the past decades but few genes have actually been identified, and no complete genetic structures of L. edodes B mating-type loci are available. In this study, we cloned the matB regions from two mating compatible L. edodes strains, 939P26 and 939P42. Four pheromone receptors were identified on each new matB region, together with three and four pheromone precursor genes in the respective strains. Gene polymorphism, phylogenetic analysis and distribution of pheromone receptors and pheromone precursors clearly indicate a bipartite matB locus, each sublocus containing a pheromone receptor and one or two pheromone precursors. Detailed sequence comparisons of genetic structures between the matB regions of strains 939P42, 939P26 and a previously reported strain SUP2 further supported this model and allowed identification of the B mating type subloci borders. Mating studies confirmed the control of B mating by the identified pheromone receptors and pheromones in L. edodes.     

Theoretical Study On The Reaction Mechanism Of Gecl3ch2ch2cooh+h2o→gecl2ohch2ch2cooh+hcl

The mechanism and dynamical properties for the title reaction have been investigated theoretically. Three reaction pathways have been found. Geometries, vibrational frequencies, infra-red (IR) intensities and relative energies for various stationary points in the three reaction channels have been determined respectively. The corresponding rate constants at the B3LYP/6-31++G(2d,2p) level have been deduced over a wide temperature range of 200–2000 K by using canonical variational transition state theory with small curvature tunnelling effect. Solvent effects are taken into account via the Onsager model of self-constant reaction field at the same level of theory. This preliminary study shows that the complex formation is favoured by the use of water solvent.     

Quantum chemical study on influence of substituents and solvents in reaction complexing ethylene with nickel dithiolene

The influences induced by various terminal substituents and solvents on the reaction mechanism and chemical dynamics of complexing ethylene with Ni dithiolene are theoretically studied by using B3LYP method and Onsager model. It is shown that the reaction should be a two-step process, and the first step is the rate-determining step. We find that the rate constant of the rate-determining step becomes small when the electron-donating ability of the substituents is increased, while it becomes large when the electron-withdrawing ability of the substituents is increased. Subsequently, we consider the solvent effects on the reaction adding ethylene to the simplified hydrogen-substituted nickel dithiolene. It is found that the solvents will make slight changes to the geometries of the reactants, transition states, intermediates and products. However, the corresponding molecular dipole moments become large with the increase of the solvent polarity, which is beneficial to accelerate the reaction. Moreover, we show that, as the solvent polarity becomes large, the activation energies of the reaction decrease exponentially, while the reaction rate constants increase exponentially. These results demonstrate that in polar solvents, the reaction complexing ethylene with Ni dithiolene may become easier and faster to occur, and the product rate is improved. We believe that this research can be seen as a reference for complex and solvent selection in olefin separation process.     

Accelerating all-atom protein folding simulations through reduced dihedral barriers

Protein folding requires extensive changes of backbone and sidechain dihedral angles, whose energy barriers constitute obstacles for the folding kinetics. Folding of small proteins is furthermore thought to be path-independent. Here, we propose that time-consuming all-atom protein folding simulations may be accelerated through a reduction of the dihedral barriers of the force field. In order to investigate this hypothesis, we performed various folding simulations of two small proteins. We report an acceleration towards smaller root-mean-square deviations from the native protein structure using our proposed method.     

Effect of the metal ion and the medium on the electronic structure of anthranilic acid: a modelling study on the Li and the BeH derivatives

This computational organic chemistry study illustrates that the size of the metal ion is a critical point in determining the bonding mode of the anthranilate (2-aminobenzoate). The beryllium model structure is the first example in the chemical literature on the ability of this amino acid to bond as N–O chelate. The medium has variable effect on the energies and the dipole moments of the studied models, which was found originating essentially from the differences in the atomic charges of the metals. Analysis of the molecular charge distribution allowed stating a new theory on the effect of the medium on the two pairs of isomers.     

Targeted delivery of insulin-modified immunoliposomes in vivo

The purpose of this study was to investigate the effect of liposomes conjugated with insulin to the surface on circulation time, biodistribution, and antitumor activity after intravenous injection in tumor-bearing mice. Immunoliposomes were constructed with insulin, which was covalently linked to liposomes containing anticancer drugs. In order to investigate the targeting performance of insulin-modified immunoliposomes (SILs) in vivo, plasma pharmacokinetics, biodistribution, and antitumor activity were tested. In comparison with nontargeted liposomes (SLs), SILs were cleared faster from circulation as a result of greater liver and tumor uptake. In addition, SILs retarded the growth of the tumor effectively, compared with the ZTO injection or SL. This is the first time for selective in vivo targeting of tumor vessels using insulin-modified immunoliposomes. SILs are candidate drug-delivery systems for therapeutic anticancer approaches.     

Characterisation of a thermo-alkali-stable lipase from oil-contaminated soil using a metagenomic approach

Lipases are widely used for a variety of biotechnological applications. Screening these industrial enzymes directly from environmental microorganisms is a more efficient and practical approach than conventional cultivation-dependent methods. Combined with activity-based functional screening, six clones with lipase activity were detected and a gene (termed lipZ01) isolated from a target clone with the highest lipase activity was cloned from an oil-contaminated soil-derived metagenomic library and then sequenced. Gene lipZ01 was expressed in Pichia pastoris GS115 and the molecular weight of the recombinant lipase LipZ01 was estimated by electrophoresis analysis to be approximately 50 kDa. The maximum activity of the purified lipase was 42 U/mL, and the optimum reaction temperature and pH value were 45 °C and 8.0, respectively. The enzyme was highly stable in the temperature range 35–60 °C and under alkaline conditions (pH 7–10). The presence of Ca²⁺ and Mn²⁺ ions could significantly enhance the activity of the lipase. The purified lipase preferentially hydrolysed triacylglycerols with acyl chain lengths ≥8 carbon atoms, and the conversion degree of biodiesel production was nearly 92% in a transesterification reaction using olive oil and methanol. Some attractive properties suggested that the recombinant lipase may be valuable in industrial applications.     

Gallic acid is the major component of grape seed extract that inhibits amyloid fibril formation

Many protein misfolding diseases, for example, Alzheimer’s, Parkinson’s and Huntington’s, are characterised by the accumulation of protein aggregates in an amyloid fibrillar form. Natural products which inhibit fibril formation are a promising avenue to explore as therapeutics for the treatment of these diseases. In this study we have shown, using in vitro thioflavin T assays and transmission electron microscopy, that grape seed extract inhibits fibril formation of kappa-casein (κ-CN), a milk protein which forms amyloid fibrils spontaneously under physiological conditions. Among the components of grape seed extract, gallic acid was the most active component at inhibiting κ-CN fibril formation, by stabilizing κ-CN to prevent its aggregation. Concomitantly, gallic acid significantly reduced the toxicity of κ-CN to pheochromocytoma12 cells. Furthermore, gallic acid effectively inhibited fibril formation by the amyloid-beta peptide, the putative causative agent in Alzheimer’s disease. It is concluded that the gallate moiety has the fibril-inhibitory activity.     

正交试验法优选复方四参颗粒剂的提取工艺

本文研究复方四参颗粒剂的提取工艺,采用正交试验法,以丹酚酸B提取率和干膏得率为指标,考察加水量、煎煮时间和煎煮次数对提取效果的影响,确立了复方四参颗粒剂的最佳提取工艺为:加8倍量水,提取2次,第一次时间为2 h,第二次为1 h。在最佳提取工艺条件下,干膏得率为16.58%,丹酚酸B的平均量为22.42mg。与正交试验的结果相符,说明该提取方法合理、稳定、可行。     

四种护脾养胃类中药水提物抗氧化能力测定

以罗丹明B为显色剂,采用分光光度法测定了护脾养胃类方剂中常见的当归、五味子、黄芩、红枣等四种中药水提物对·OH的清除能力.实验表明:这些中药永提取物对·OH都具有较强的清除作用,呈现明显的量效关系,其中红枣的清除能力最强.据此评价了这四种中药水提取物抗氧化能力大小顺序为:红枣＞当归＞黄芩＞五味子.