The influence of Al3+ ion on porcine pepsin activity in vitro

The in vitro effect of Al³⁺ ions in the concentration range 1.7·10^{? 6} M–8.7·10^{? 3} M on pepsin activity at pH 2, via kinetic parameters and its electrophoretic mobility was evaluated. Kinetic study demonstrated the existence of an activation effect of Al³⁺ at pH 2 on pepsin molecule. Kinetic analysis with respect to concentrations of haemoglobin showed that Al³⁺ ions increase the maximal velocity (V_max) and k_cat values rather than apparent affinity for substrate (K_S) implying the non-competitive nature of activation which indicated that aluminium was a non-essential activator of partial non-competitive type. The values of the equilibrium constants K_S and K_mA for dissociation of corresponding complexes were evaluated as 0.904 ± 0.083 mM and 8.56 ± 0.51 μM, respectively. Dissociation constant K_A, of activator from enzyme-activator complex calculated via kinetic and direct measurement of Al³⁺ binding data, as well as activation constant A₅₀, the activator concentration that gives a rate equal to half at a saturating concentration of activator, were found to be 8.82 ± 0.90 μM, 8.39 ± 0.76 μM, and 8.05 ± 0.48 μM respectively. Native PAGE electrophoresis shows the decrease in electrophoretic mobility of pepsin and confirms modification of the electric charge and conformational changes of pepsin caused by bound Al³⁺ on the pepsin molecule. Al³⁺ induced conformational changes of pepsin were verified by UV-VIS and IR spectra. Moreover, the absence of conformational changes in the haemoglobin molecule in the presence of Al³⁺ ions confirms that the obtained activation is a consequence of conformational changes caused only in the pepsin molecule.     

红豆草耐盐愈伤组织的筛选及植株再生

将红豆草种子在含１．２％ＮａＣｌ的ＭＳ培养基上萌发以消除盐敏感的幼苗,把存活的幼苗下胚轴切段在含１ｍｇ／Ｌ２,４－Ｄ、０．５ｍｇ／Ｌ６－ＢＡ及１．２％ＮａＣｌ的ＭＳ培养基上诱导愈伤组织,通过连续筛选得到可耐受１．８％ＮａＣｌ的愈伤组织,在有０．２ｍｇ／Ｌ ＮＡＡ和１ｍｇ／Ｌ ＩＡＡ存在下该愈伤组织分化出芽,待幼,待幼苗长至３ｃｍ左右时转至含２ｍｇ／ＬＮＡＡ和或ＩＢＡ的１／２ＭＳ培养基上生根。对对照     

不同大豆基因型对农杆菌敏感性研究及优异种质筛选

大豆遗传转化一直是植物基因工程领域的难点之一,受体品种对农杆菌的敏感程度以及不同农杆菌菌株对靶组织的侵染能力是影响转化效率的主要因素。本研究利用GUS组织瞬时表达技术,比较了4个农杆菌菌株对靶组织子叶节的侵染能力差异,同时利用筛选到的侵染能力最强的菌株评估了33个不同受体基因型对农杆菌的敏感性。结果表明,超毒农杆菌菌株Ag10对靶组织的侵染能力最强,优于其他3个菌株;地方与野生大豆种质在农杆菌侵染后GUS的平均瞬时表达效率显著高于选育品种。此外,通过鉴定筛选出6个对农杆菌敏感性较高的受体材料,其对农杆菌的敏感性优于前人报道的敏感材料Peking,为大豆高效遗传转化体系的建立和新型转化受体的开发提供了参考。     

Morphology and proliferation of B16 melanoma cells in the presence of lanthanoid and Al3+ ions

The effects of trivalent metal ions such as lanthanoid (La , Ce, Nd , Sm , Gd , Er , Yb , Lu ) and Al ions on the morphological change and proliferation of B16 melanoma cells in culture are discussed. These metal ions induced morphological transformations and decreased growth rates at doses of 1 mM. B16 melanoma cells treated with La , Ce , Nd , Sm , and Gd showed polyhedrical spreading. Elongation of axones was dependent on the metal ions. B16 melanoma cells treated with Er , Yb , Lu , and Al showed a long slender shape. Growth rates of melanoma cells in the presence of 1 mM of metal ions (La , Ce , Nd , Sm , Gd , Yb , Al ) were significantly lower than that of control cells. Measurements of cell cycle indicated that the metal ions arrested the transitions from G /G to S state. © Rapid Science 1998     

铝、镉对小麦幼苗生长的影响及其DNA损伤效应研究

本研究旨在探索Al^3＋、Cd^2＋对小麦幼苗生长的影响及其DNA损伤效应。结果表明：（1）所试浓度Al^3＋、Cd^2＋不仅不同程度抑制2d龄和12d龄幼苗根系和地上部分的生长,而且表现明显的DNA损伤效应;（2）除Al^3＋对幼苗地上部分鲜重、干重的影响及Cd^2＋对幼苗根系生长速率的影响外,其余生长指标显示2d龄幼苗比12d龄幼苗对Al^3＋、Cd^2＋更敏感,这与导致2d龄幼苗DNA损伤的Al^3＋、Cd^2＋浓度明显低于12d龄幼苗的结果一致。研究结果表明,DNA损伤可能是Al^3＋、Cd^2＋抑制2d龄和12d龄小麦幼苗生长的重要原因之一。     

The effects of KNO3 concentration in callus induction medium for wheat anther culture

KNO₃ concentration was found to significantly affect the anther culture of wheat (Triticum aestivum L.). When KNO₃ was increased from 0 to 15 mM (in cultivar Jinghua 1) or from 10 to 15 mM (in cultivars 2531-10, Xiaoyan 759 and Norin 10), the callus induction frequency increased significantly. When KNO₃ was increased further above 20 mM, the callus induction frequency decreased significantly in all the tested cultivars. The subsequent frequency of green plantlet regeneration increased significantly, and the ratio of green to albino regenerants increased sharply when KNO₃ concentration increased. Further experiments found that the decrease of callus induction frequency in the medium with too much KNO₃ might be caused by NO₃ ^- ion alone, while the effect of KNO₃ on green plantlet regeneration might be caused by both K⁺ and NO₃ ^- ions, and that the effects of NO₃ ^- concentration were independent of NH₄ ⁺ concentration in the medium.     

Application of a MTT assay for screening nutritional factors in growth media of primary sponge cell culture

Marine sponges (Porifera) are producers of the largest variety of bioactive compounds among benthic marine organisms. In vitro culture of marine sponge cells has been proposed for the sustainable production of these pharmacologically interesting compounds from marine sponges but with limited success. The development of a suitable growth medium is an essential prerequisite for sponge cells grown in vitro. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was adapted to screen for potential nutritional factors in formulating a growth medium for primary cell culture of Suberites domuncula. In 96-well plates, the effects of nutritional factors including glutamine, pyruvate, iron citrate, silicon, RPMI 1640, and Marine Broth 2216 on the viable cell density were examined in primary cell culture of S. domuncula 36 h after inoculation. Ferric iron (Fe(3+)) and pyruvate were found to significantly improve cell viability in a dose-dependent manner. Silicon and glutamine showed limited improvements at certain concentrations. The supplement of RPMI 1640 and Marine Broth 2216 did not increase cell viability. As a result, several improved media able to maintain higher cell viability in a short-term culture of primary sponge cells could be formulated.     

Influence of Al3+ on the titer of spiramycin and effective components in fermentor

Spiramycin is a multicomponent antibiotic, and different components have different antibacterial activities. In Streptomyces spiramyceticus 16-10-2, spiramycin II and spiramycin III (SPMII and SPMIII) are the main components, while spiramycin I (SPMI) needs to be controlled below 12%. Based on this, the influences of Al³⁺ on total spiramycin titer and components were investigated in this work. Those experiments were mainly performed in 15?L fermentor and Al³⁺ made a great improvement in spiramycin titer. The optimal adding concentration and adding time of Al³⁺ were 0.32?g/L at 12?hr. Under this condition, spiramycin titer was increased by 19.51% compared with the control. Moreover, the percentage of SPMII and SPMIII was increased by 7.14%. At the same time, the time of mycelia autolysis was lengthened. In addition, the specific activities of acetyl-CoA synthetase, acetate kinase, acetylphosphotransferase, and acylating enzyme were much higher than those of control. The content of acetic acid and succinic acid was beyond 3 and 4.5 times than that of control, respectively.     

Improving green emission of Tb3+ ions in BaO‐B2O3‐P2O5 glasses by means of Al3+ ions

BaO‐B₂O₃‐P₂O₅ glasses doped with a fixed concentration of Tb³⁺ ions and varying concentrations of Al₂O₃ were synthesized, and the influence of the Al³⁺ ion concentration on the luminescence efficiency of the green emission of Tb³⁺ ions was investigated. The optical absorption, excitation, luminescence spectra and fluorescence decay curves of these glasses were recorded at ambient temperature. The emission spectra of terbium ions when excited at 393 nm exhibited two main groups of bands, corresponding to ⁵D₃ → ⁷F_j (blue region) and ⁵D₄ → 7F_j (green region). From these spectra, the radiative parameters, viz., spontaneous emission probability A, total emission probability A_T, radiative lifetime τ and fluorescent branching ratio β, of different transitions originating from the ⁵D₄ level of Tb³⁺ ions were evaluated based on the Judd‐Ofelt theory. A clear increase in the quantum efficiency and luminescence of the green emission of Tb³⁺ ions corresponding to ⁵D₄ → ⁷F₅ transition is observed with increases in the concentration of Al₂O₃ up to 3.0 mol%. The improvement in emission is attributed to the de‐clustering of terbium ions by Al³⁺ ions and also to the possible admixing of wave functions of opposite parities. Copyright © 2016 John Wiley & Sons, Ltd.     

Optimization of culture media for in vitro rooting of Malus domestica Borkh. cv. Compact Spartan

Shoots of Malus domestica Borkh. cv. Compact Spartan raised in vitro do not root in a single auxin medium. Components of the rooting medium were tested not only for root initiation but also for root elongation. Root emergence and further growth were inhibited by a too prolonged auxin treatment, the presence of NH4NO3 and the lack of substrate aeration. Saccharose was essential to achieve highly reproducible root growth on agar but was not necessary on watered vermiculite. Ca(NO3)2 stimulated root initiation, emergence and growth and improved their viability. This revised version was published online in July 2006 with corrections to the Cover Date.     

Luminescence properties of novel deep‐red‐emitting Ca3Al2Ge2O10:Cr3+ phosphors

Ca₃Al₂Ge₂O₁₀:Cr³⁺ phosphors were prepared by a high‐temperature solid‐state method, and their luminescence properties were investigated. Under excitation at 550 nm, Ca₃Al₂Ge₂O₁₀:Cr³⁺ phosphors exhibited a broad red emission band at 697 nm in the range 650–750 nm that was caused by the ²E→⁴A₂ transition of Cr³⁺. For the 697 nm emission peak, emission intensity reached a maximum at x = 0.07, and there was concentration quenching of Cr³⁺ in Ca₃Al₂Ge₂O₁₀; the corresponding concentration quenching mechanism was analysed. Under excitation at 262 nm, the Ca₃Al₂Ge₂O₁₀:Cr³⁺ phosphor showed a weakly broad emission band in the range 350–600 nm that was caused by intrinsic defects (V′′_Ca and V′′_O). Copyright © 2016 John Wiley & Sons, Ltd.     

Fractional factorial approach combining 4 Escherichia coli strains, 3 culture media, 3 expression temperatures and 5 N-terminal fusion tags for screening the soluble expression of recombinant proteins

Producing recombinant proteins in Escherichia coli (E. coli) is generally performed using a trial and error approach with the different expression variables being tested independently from each other. As a consequence, variable interactions are lost which makes the trial and error approach quite time-consuming. In this paper, we report how switching from a trial and error to a fractional factorial approach allows testing in less than 2 weeks four expression variables (E. coli strains, culture media, expression temperatures and N-terminal fusion tags) in a single experiment. The method, called "Fusion-InFFact", was validated using four test proteins. In all cases, Fusion-InFFact allowed finding conditions for expressing high yields of soluble proteins. The method was originally set-up for high throughput structural genomics programs, but can be used in any recombinant protein expression project.     

HPLC analysis of lipoproteins in culture medium of hepatoma cells: an in vitro system for screening antihyperlipidemic drugs

We isolated a HepG2-derived sub-clone (HepG2-Lipo), which possessed an increased lipoprotein synthesizing ability. HepG2-Lipo cells could secrete triglycerides (TG) and cholesterol at rates 9.4- and 6-fold higher, respectively, when compared to HepG2 cells. Real-time RT-PCR analysis revealed that the expression levels of sterol regulatory element-binding protein-1c and -2 were 2.9- and 1.5-fold higher than in HepG2 cells. Furthermore, two apolipoprotein (apo) genes (apoA-1 and apoB-100) in HepG2-Lipo cells were expressed at 2.8- and 1.9-fold higher levels when compared to those in parental cells. We examined the effects of three antihyperlipidemic agents on the lipoprotein profiles of HepG2-Lipo cells. Simvastatin at 5 μM selectively suppressed cholesterol secretion from HepG2-Lipo cells, and 500 μM fenofibrate inhibited both TG and cholesterol secretion from the cells.     

Comparison of two methods for callus culture and plant regeneration in wheat (Triticum aestivum)

Callus growth and development involve a complex relationship between the explants used to initiate callus, the constituents of the medium and the environmental conditions during culturing. Use of high molecular weight osmotica such as polyethylene glycol (PEG-4000) results in non-solidification of agar medium used for culturing and selection. Thus, a new filter paper bridge technique was compared with the existing agar medium for callus initiation, multiplication, and plant regeneration of wheat. The yield of both total and embryogenic callus was doubled and significantly higher number of regenerants was obtained on filter paper bridges compared to agar medium.     

Optimization of a mature embryo-based in vitro culture system for high-frequency somatic embryogenic callus induction and plant regeneration from japonica rice cultivars

Optimization of the conditions for an efficient induction of somatic embryogenic calli and regeneration of plants from mature seeds of japonica rice cultivars was attempted. The number, color, size, shape, and appearance time of the induced embryogenic calli varied among the rice cultivars depending on the type of basal medium (LS, MS, N6). Presence of adequate amount of sucrose in the medium was an absolute requirement for embryogenic callus formation and shoot induction. Induction of the embryogenic calli, whose overall rates ranged from 30 to 56%, was most efficient in N6 medium supplemented with 3.0 mg l^–1 of 2,4-D and 30 g l^–1 of sucrose. Agar concentration in the regeneration medium was also critical for the shoot induction. Kinetin was found to be more effective for shoot regeneration compared with BA, while the highest shoot regeneration frequencies were observed when either cytokinin was combined with high concentration (2.0 mg l^–1) of NAA. The optimal concentration of kinetin for the highest shoot regeneration frequency (6777%) was different among the cultivars tested. The embryogenic calli-derived shoots rooted on a plant growth regulator-free MS medium were successfully established in soil, producing fertile seeds.     

Combined actions of Pb2+, Zn2+, and Al3+ on voltage-activated calcium channel currents

Summary 1. Whole-cell patch clamp experiments were performed on rat dorsal root ganglion (DRG) neurons to investigate the actions of various combinations of Pb²⁺, Zn²⁺, and Al³⁺ on voltage-activated calcium channel currents (VACCCs).2. Each of these metals has been shown to reduce VACCCs.3. We investigated the effects of simultaneous application of two cations in the range of their IC₅₀ values. For all possible combinations (Pb²⁺/Zu²⁺, Zn²⁺/Al³⁺, Al³⁺/Pb²⁺), independent of the order of application, we found additive actions on VACCCs.4. We observed a 75% (±9%) block of the control current when two cations were applied simultaneously. This observation is consistent with both, an action of two metals at the same site as well as independent actions at different locations of the ion channel.5. The additivity of the effects should be taken into account for questions of public health and the assessment of threshold limits in cases of environmental contamination.     

A highly selective aggregation‐induced emission fluorogen for sensitive detection of Al3+ in living cells

A Schiff's base derivative was synthesized using a condensation reaction between 8‐formyl‐7‐hydroxy‐4‐methylcoumarin and furan‐2‐carbohydrazide that produced marked aggregation‐induced emission and had excellent ability to specifically recognize aluminium ions (Al³⁺). This compound displayed faint fluorescence in the benign solvent dimethyl formamide, and exhibited obvious green fluorescence following addition of specific amounts of water. Moreover, it exhibited strong blue fluorescence after combination with Al³⁺ even in the presence of other interfering ions. These experimental results demonstrated that this derivative could be used as a fluorescence probe for Al³⁺. The advantages, including significant fluorescence change, high selectivity and sensitivity, and fast response, meant that this probe could be used both to detect Al³⁺ in water samples and for fluorescence imaging in living cells.     

A red fluorescent carbon dots with good water solubility for rapid detection of Al3+ in actual samples

We developed a facile strategy for the fabrication of red fluorescent carbon nanodots (R-CDs) and demonstrated their applications for Al³⁺ sensing. Red-emission carbon dots (CDs) were synthesized using a simple hydrothermal treatment with citric acid and urea as precursors, manifesting intriguing red-emission behaviour at 610 nm. With increasing Al³⁺ concentration, the fluorescence band at 610 nm decreased gradually. Monitoring the intrinsic fluorescence variation (I_610nm), as-prepared CDs were developed as an effective platform for fluorescent Al³⁺ sensing, with a linear range of 0.5–60.0 μM and a detection limit of 3.0 nM. More importantly, R-CDs have been applied successfully to the analysis of Al³⁺ in actual samples with satisfactory recoveries in the range 97.12–102.05%, which indicated that obtained CDs could be implemented as an effective tool for the identification and detection of Al³⁺ in actual samples.     

Intensity enhancement of photoluminescence in Tb3+/Eu3+ co-doped Ca14Zn6Al10O35 phosphor for WLEDs

This article focuses on the effect of monovalent cation doping on the optical properties of rare earth (RE = Eu³⁺, Tb³⁺) co-doped Ca₁₄Zn₆Al₁₀O₃₅ which has been synthesized by a low temperature combustion method. Crystalline phase of the Ca₁₄Zn₆Al₁₀O₃₅ phosphor was examined and confirmed by X-ray diffraction measurement. Under near-ultraviolet light excitation Eu³⁺-doped Ca₁₄Zn₆Al₁₀O₃₅ phosphor exhibit characterization of Eu³⁺ emission bands that are located at a maximum wavelength (λ_max) of approximately 470 nm and other peaks centred at 593 nm and 615 nm, respectively. With Tb³⁺-doped Ca₁₄Zn₆Al₁₀O₃₅ phosphor showing a green emission band centred at 544 nm under near-ultraviolet range. Furthermore, we studied the energy transfer process in Eu³⁺/Tb³⁺pair and enhancement in photoluminescence (PL) intensity with doping different charge compensation. Here we obtained the optimum PL emission intensity of the phosphor in broad and intense visible spectral range which may be significant for the fabrication of white light emitting diodes (WLEDs).