产L-乳酸米根霉PW352特性及低能离子注入诱变高产菌株研究

为了获得更适于工业生产的产乳酸菌株,以葡萄糖为碳源对PW352菌株特性进行了研究,并在此基础上采用离子束诱变方法,对米根霉PW352进行改良,获得高产L( )—乳酸菌株RE3303,产酸能力达131～136g／L,最高可达140g／L,糖转化率为86％～90％,产酸比PW352提高75％。     

氮离子注入棉花花粉诱发农艺性状变异的研究

Ｎ＋注入陆地棉和海岛棉的成熟花粉用于自交和远缘杂交,结果表明：离子注入花粉,在Ｍ１代就可表出现较高频率的有益突变,在Ｍ１相对成苗率和花粉育性为５０％时,花粉辐照Ｍ２突变率是种子辐照的１．６倍,用Ｎ＋离子注入陆地棉和海岛棉花粉进行正反远缘杂交,Ｆ２Ｍ２农艺性状表现出偏母遗传且后代遗传稳定加快,并观察到父本某些性状的转移。离子注入花粉适宜的剂量范围为２×１０１５—１０×１０１５Ｎ＋／ｃｍ２。     

Lithiation‐Induced Dilation Mapping in a Lithium‐Ion Battery Electrode by 3D X‐Ray Microscopy and Digital Volume Correlation

Recent advances in high‐resolution 3D X‐ray computed tomography (CT) allow detailed, non‐destructive 3D structural mapping of a complete lithium‐ion battery. By repeated 3D image acquisition (time lapse CT imaging) these investigations of material microstructure are extended into the fourth dimension (time) to study structural changes of the device in operando. By digital volume correlation (DVC) of successive 3D images the dimensional changes taking place during charge cycling are quantified at the electrode level and at the Mn₂O₄ particle scale. After battery discharging, the extent of lithiation of the manganese (III/IV) oxide grains in the electrode is found to be a function of the distance from the battery terminal with grains closest to the electrode/current collector interface having the greatest expansion (≈30%) and grains furthest from the current collector and closest to the counter electrode showing negligible dilation. This implies that the discharge is limited by electrical conductivity. This new CT+DVC technique is widely applicable to the 3D exploration of the microstructural degradation processes for a range of energy materials including fuel cells, capacitors, catalysts, and ceramics.     

Glutathione peroxidase‐like enzymes cover five distinct cell compartments and membrane surfaces in Arabidopsis thaliana

Glutathione peroxidase‐like enzymes (GPXLs) constitute a family of eight peroxidases in Arabidopsis thaliana. In contrast to the eponymous selenocysteine glutathione peroxidases in mammalian cells that use glutathione as electron donor, GPXLs rely on cysteine instead of selenocysteine for activity and depend on the thioredoxin system for reduction. Although plant GPXLs have been implicated in important agronomic traits such as drought tolerance, photooxidative tolerance and immune responses, there remain major ambiguities regarding their subcellular localization. Because their site of action is a prerequisite for an understanding of their function, we investigated the localization of all eight GPXLs in stable Arabidopsis lines expressing N‐terminal and C‐terminal fusions with redox‐sensitive green fluorescent protein 2 (roGFP2) using confocal microscopy. GPXL1 and GPXL7 were found in plastids, while GPXL2 and GPXL8 are cytosolic nuclear. The N‐terminal target peptide of GPXL6 is sufficient to direct roGFP2 into mitochondria. Interestingly, GPXL3, GPXL4 and GPXL5 all appear to be membrane bound. GPXL3 was found exclusively in the secretory pathway where it is anchored by a single N‐terminal transmembrane domain. GPXL4 and GPXL5 are anchored to the plasma membrane. Presence of an N‐terminal myristoylation motif and genetic disruption of membrane association through targeted mutagenesis point to myristoylation as essential for membrane localization.     

A colorimetric and fluorescent probe for fluoride ions based on 6‐acetyl‐2‐naphthol

A colorimetric and turn‐on fluorescent probe for fluoride ions, tert‐butyldimethylsilane 6‐acetyl‐2‐naphtholate, was readily synthesized from 6‐acetyl‐2‐naphthol and tert‐butyldimethylchlorosilane (TBSCl). The probe exhibits high sensitivity and good selectivity for fluoride ions in acetonitrile. The inherent mechanism involves the cleavage of the Si–O bond in the probe, which induced yellow color formation and prominent fluorescence enhancement. Copyright © 2013 John Wiley & Sons, Ltd.     

钙稳态失衡与癌细胞抑制

细胞胞浆钙离子浓度必须处于严格的调控之中,钙稳态失调必将导致细胞严重损伤或死亡（凋亡或坏死）.综述了钙稳态失调在外界因素引起细胞死亡中的作用、直接钙稳态失调的细胞死亡效应、以及钙离子在细胞凋亡中的作用,并讨论了上述作用的机制,最后在总结基础上提出了一种抑癌新途径——选择性引发癌细胞钙稳态失衡.     

Structural determinants of the integrin transmembrane domain required for bidirectional signal transmission across the cell membrane

Studying the tight activity regulation of platelet-specific integrin α_IIbβ₃ is foundational and paramount to our understanding of integrin structure and activation. α_IIbβ₃ is essential for the aggregation and adhesion function of platelets in hemostasis and thrombosis. Structural and mutagenesis studies have previously revealed the critical role of α_IIbβ₃ transmembrane (TM) association in maintaining the inactive state. Gain-of-function TM mutations were identified and shown to destabilize the TM association leading to integrin activation. Studies using isolated TM peptides have suggested an altered membrane embedding of the β₃ TM α-helix coupled with α_IIbβ₃ activation. However, controversies remain as to whether and how the TM α-helices change their topologies in the context of full-length integrin in native cell membrane. In this study, we utilized proline scanning mutagenesis and cysteine scanning accessibility assays to analyze the structure and function correlation of the α_IIbβ₃ TM domain. Our identification of loss-of-function proline mutations in the TM domain suggests the requirement of a continuous TM α-helical structure in transmitting activation signals bidirectionally across the cell membrane, characterized by the inside-out activation for ligand binding and the outside-in signaling for cell spreading. Similar results were found for α_Lβ₂ and α₅β₁ TM domains, suggesting a generalizable mechanism. We also detected a topology change of β₃ TM α-helix within the cell membrane, but only under conditions of cell adhesion and the absence of α_IIb association. Our data demonstrate the importance of studying the structure and function of the integrin TM domain in the native cell membrane.     

A Novel Graphene Oxide Wrapped Na2Fe2(SO4)3/C Cathode Composite for Long Life and High Energy Density Sodium‐Ion Batteries

The cathode materials in the Na‐ion battery system are always the key issue obstructing wider application because of their relatively low specific capacity and low energy density. A graphene oxide (GO) wrapped composite, Na₂Fe₂(SO₄)₃@C@GO, is fabricated via a simple freeze‐drying method. The as‐prepared material can deliver a 3.8 V platform with discharge capacity of 107.9 mAh g^?1 at 0.1 C (1 C = 120 mA g^?1) as well as offering capacity retention above 90% at a discharge rate of 0.2 C after 300 cycles. The well‐constructed carbon network provides fast electron transfer rates, and thus, higher power density also can be achieved (75.1 mAh g^?1 at 10 C). The interface contribution of GO and Na₂Fe₂(SO₄)₃ is recognized and studied via density function theory calculation. The Na storage mechanism is also investigated through in situ synchrotron X‐ray diffraction, and pseudocapacitance contributions are also demonstrated. The diffusion coefficient of Na⁺ ions is around 10^?12–10^?10.8 cm² s^?1 during cycling. The higher working voltage of this composite is mainly ascribed to the larger electronegativity of the element S. The research indicates that this well‐constructed composite would be a competitive candidate as a cathode material for Na‐ion batteries.     

A new approach for improving cordycepin productivity in surface liquid culture of Cordyceps militaris using high‐energy ion beam irradiation

Aims: To obtain a higher cordycepin production using Cordyceps militaris mutant obtained by a new mutagenesis technique called ‘ion beam’. Methods and Results: Successful irradiation of C. militaris NBRC 9787 by a proton beam with high energy was performed, and 30 classes of 8‐azaadenine‐ and 28 classes of 8‐azaaguanine‐resistant mutants were obtained on mutant screening, of which seven classes were selected as promising preliminary mutants having an antibacterial ability as an index of cordycepin production. In a surface liquid culture technique, some of the 8‐azaadenine‐resistant mutants gave a better performance for the cordycepin productivity; in contrast, among the 8‐azaaguanine‐resistant mutants, it was shown that mutant no. G81‐3 was much better than the control in the metabolic rate of glucose and the cordycepin productivity. In primary optimization using the enriched medium, the cordycepin production was 3·1 and 1·8 g l^?1 on 21‐day culture for mutant no. G81‐3 and the control, respectively. The cordycepin production obtained by the mutant was 72% more than the control. Conclusions: The mutant obtained by proton beam irradiation had higher productivity of cordycepin than that of the control. Significance and Impact of the Study: The mutant obtained by irradiation had a superior production performance of cordycepin, and therefore, it could be used in the realm of applied industrial biotechnology for the large‐scale production of cordycepin.     

Large-conductance cationic channels in the nuclear envelope of Purkinje neurons from the rat cerebellum

Using a patch-clamp technique, we studied the biophysical properties of large-conductance channels in the nuclear envelope of rat cerebellar Purkinje neurons. Our experiments showed that channels with identical conductance, selectivity, and kinetics are expressed in the external and internal nuclear membranes of these cells. These channels connect the perinuclear space with the cyto-and nucleoplasm; they are not channels of the complex of the nuclear pores for passive diffusion of ions and small molecules, as was believed earlier [17]. We hypothesize that large-conductance cationic channels in the membranes of the nuclear envelope are identical to ion channels of the endoplasmic reticulum and are necessary for functioning of the intermembrane space of the envelope as a calcium store. Neirofiziologiya/Neurophysiology, Vol. 39, No. 2, pp. 113–118, March–April, 2007.