Plasmodium falciparum: immunization with MSP1-42 induced non-inhibitory antibodies that have no blocking activities but enhanced the potency of inhibitory anti-MSP1-42 antibodies

Hyperimmunization with Plasmodium falciparum MSP1-42 could induce antibodies that have little or no parasite growth inhibitory activities. These antisera had no blocking activities as determined by their ability to interfere with the in vitro activities of growth inhibitory anti-MSP1-42 sera. Equally important, they enhanced the potency of growth inhibitory anti-MSP1-42 sera.     

Purification and characterization of a psychrophilic glutathione reductase from Antarctic ice microalgae <Emphasis Type="Italic">Chlamydomonas</Emphasis> sp. Strain ICE-L

A psychrophilic glutathione reductase from Antarctic ice microalgae Chlamydomonas sp. Strain ICE-L was purified by ammonium sulfate fractionation and three steps of chromatography. The yield was up to 25.1% of total glutathione reductase in the crude enzyme extract. The glutathione reductase activity was characterized by the spectrophotometric method under different conditions. Purified glutathione reductase was separated by SDS-PAGE, which furnished a homogeneous band. The native molecular mass of the enzyme was 115 kDa. Apparent Km values for NADPH and NADH (both at 0.5 mmol L⁻¹ oxidized glutathione) were 22.3 and 83.8 μmol L⁻¹, respectively. It was optimally active at pH 7.5, and it was stable from pH 5 to 9. Its optimum temperature was 25°C, with activity at 0°C 23.5% of the maximum. Its optimum ion strength and optimum Mg²⁺ were 50–90 and 7.5 mmol L⁻¹, respectively. Ca²⁺, Mg²⁺, and cysteine substantially increased the activity of the enzyme but chelating agents, heavy metals (Cd²⁺, Pb²⁺, Cu²⁺, Zn²⁺, etc.), NADPH, and ADP had significant inhibitory effects. This glutathione reductase can be used to study the adaptation and mechanism of catalysis of psychrophilic enzymes, and it has a high potential as an environmental biochemical indicator under extreme conditions.     

On the dynamics of electrically-coupled neurons with inhibitory synapses

We study the dynamics and bifurcations of noise-free neurons coupled by gap junctions and inhibitory synapses, using both delayed delta functions and alpha functions to model the latter. We focus on the case of two cells, as in the studies of Chow and Kopell (2000) and Lewis and Rinzel (2003), but also show that stable asynchronous splay states exist for globally coupled networks of N cells dominated by subthreshold electrical coupling. Our results agree with those of Lewis and Rinzel (2003) in the weak coupling range, but our Poincaré map analysis yields more information about global behavior and domains of attraction, and we show that the explicit discontinuous maps derived using delayed delta functions compare well with the continuous history-dependent, implicitly-defined maps derived from alpha functions. We find that increased bias currents, super-threshold electrical coupling and synaptic delays promote synchrony, while sub-threshold electrical coupling and fast synapses promote asynchrony. We compare our analytical results with simulations of an ionic current model of spiking cells, and briefly discuss implications for stimulus response modes of locus coeruleus and for central pattern generators. Action Editor: F. Skinner     

Chemical composition and antifungal efficacy of five essential oils against Calonectria pseudonaviculata,the causal agent of boxwood blight: an in vitro study

Recent epidemics of box (boxwood) blight caused by the fungus Calonectria pseudonaviculata in Hyrcanian forests led to the search for eco-friendly fungicides. Essential oils (EOs) of medicinal plants undoubtedly have been highlighted as a new therapeutic approach. In this study, EOs from Cuminum cyminum, Lavandula angustifolia, Thymus daenensis, Trachyspermum copticum and Hyssopus officinalis were evaluated for their inhibitory activities against C. pseudonaviculata Cy-08 in vitro. Quantitative and qualitative composition variations of the EOs were also analysed by GC–MS. Based on the high inhibitory efficacy and low related EC₅₀, MFC and MIC values, T. copticum, L. angustifolia and Th. daenensis EOs can be mentioned as those providing extraordinary efficacy against Cy-08, respectively. Major chemical components of T. copticum, L. angustifolia and Th. daenensis EOs were thymol, linalyl acetate and thymol, respectively. Thymol and linalyl acetate may be the most effective compounds against C. pseudonaviculata.     

兴奋性突触传入对皮层神经元形态发育的影响

目的:探讨离子型谷氨酸受体中的AMPA受体(α-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor, AMPA受体)和NMDA受体(N-methyl-D-aspartic acid receptor)对抑制性中间神经元以及兴奋性神经元的形态发育的影响。方法:采用原代培养皮层神经元,通过药物干预AMPA受体和/或NMDA受体的方法阻断神经元的离子型谷氨酸受体,并采用GAD67-GFP鼠的绿色荧光来显示混合细胞群中抑制性神经元、CaMKII免疫荧光染色显示兴奋性神经元。结果:当阻断AMPA和/或NMDA受体时,光镜下显示神经元网络的密度降低,且随着药物浓度的增加,神经元网络的变化更明显。对于GFP阳性的抑制性神经元,当阻断AMPA受体时,神经元突起分支数降低至对照组的约65%(低浓度)和55%(高浓度),突起长度缩短至对照组的大约43%(低浓度)和36%(高浓度);当阻断NMDA受体时,分支数降低至约70%(低浓度)和45%(高浓度),长度缩短至约43%(低浓度)和31%(高浓度);联合用药时,分支数和长度分别为对照的约42%和38%。对于CaMKII阳性的兴奋性神经元,尽管变化程度稍弱,但其形态也出现类似变化。当阻断AMPA受体时,神经元的分支数降低至对照组的64%(高浓度),突起长度变化不大;当阻断NMDA受体时,分支数降低至约50%(高浓度),长度缩短至约77%(低浓度)和71%(高浓度);联合用药时,分支数和长度分别为对照的约69%和62%。结论:在神经元发育的过程中,离子型谷氨酸受体介导的兴奋性突触传入可影响抑制性神经元和兴奋性神经元的形态发育,最终对神经环路的形成发挥重要的调控作用。     

In vitro effect of important herbal active constituents on human cytochrome P450 1A2 (CYP1A2) activity

This study was designed to investigate eight herbal active constituents (andrographolide, asiaticoside, asiatic acid, madecassic acid, eupatorin, sinensetin, caffeic acid, and rosmarinic acid) on their potential inhibitory effects on human cytochrome P450 1A2 (CYP1A2) activity. A fluorescence-based enzyme assay was performed by co-incubating human cDNA-expressed CYP1A2 with its selective probe substrate, 3-cyano-7-ethoxycoumarin (CEC), in the absence or presence of various concentrations of herbal active constituents. The metabolite (cyano-hydroxycoumarin) formed was subsequently measured in order to obtain IC₅₀ values. The results indicated that only eupatorin and sinensetin moderately inhibited CYP1A2 with IC₅₀ values of 50.8 and 40.2 μM, while the other active compounds did not significantly affect CYP1A2 activity with IC₅₀ values more than 100 μM. K_i values further determined for eupatorin and sinensetin were 46.4 and 35.2 μM, respectively. Our data indicated that most of the investigated herbal constituents have negligible CYP1A2 inhibitory effect. In vivo studies however may be warranted to ascertain the inhibitory effect of eupatorin and sinensetin on CYP1A2 activity in clinical situations     

Inhibitory effects of leachate from Eupatorium adenophorum on germination and growth of Amaranthus retroflexus and Chenopodium glaucum

Amaranthus retroflexus L. and Chenopodium glaucum L. are two widely distributed destructive weeds. Their strong adaptability and massive seed production make them the hardest weeds to deal with. This present study intended to investigate the effect of leachate from Eupatorium adenophorum on the growth of these weeds and explore the potential to develop an environmental friendly strategy to use the leachate to control the weeds. Seeds of A. retroflexus L. and C. glaucum L. were soaked in solutions containing 0%, 0.6%, 1.25%, 2.5%, and 5% leachate from E. adenophorum leaves. A. retroflexus and C. glaucum seedlings grown in pots were sprayed with leachate solutions in the same concentration range. The effects of these leachate solutions on membrane permeability and germination of seeds, and growth and physiological characteristics of the seedlings were investigated. The highest concentration of leachate (5%) caused significant damage to the cell membrane of seeds of both weed species, whereas lower concentrations (0.6%) promoted repair of the membrane system, as reflected by higher and lower than control in relative conductivity (RC), respectively. Different concentrations of leachate showed distinct allelopathic inhibitory effects on the two weed species; lower concentrations showed weak inhibitory or even positive effects, whereas higher concentrations showed stronger inhibitory effects. Higher concentrations of leachate (2.5% and 5%) delayed germination and significantly decreased the emergence rate of the seeds, survival rate, and dry matter accumulation of the seedlings. When treated by 5% leachate, the emergence date of A. retroflexus was delayed by 3.6 d, emergence rate of the seeds and survival rate was 69.1% and 70.6% of the control, respectively, seedling dry matter was 48.6% less than the control; In the case of C. glaucum, the emergence date was delayed by 2.7 d, emergence rate of the seeds and survival rate was 45.1% and 58.6% of the control, respectively, seedling dry matter was 44.7% less than the control. There were significant interactions among the different concentrations of leachate and the length of treatment period with respect to activities of antioxidant enzymes, malondialdehyde (MDA) contents, and chlorophyll contents. Seedlings treated with 0.6%, 1.25%, or 2.5% leachate solution for 24–72 h showed increased superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities. When seedlings were treated with leachate solutions for 96 h, antioxidant enzyme activities and chlorophyll content decreased in A. retroflexus, but only CAT activity decreased in C. glaucum. When seedlings of the two weed species were treated with 5% leachate solution, CAT activity and chlorophyll content decreased and MDA content gradually increased with longer treatment times (from 24 to 96 h). The two weed species showed different allelopathic responses to E. adenophorum; A. retroflexus was more sensitive than C. glaucum. Based on the investigation, it could be speculated that the delayed germination and low germination rate of the weeds after treatment by leachate could be due to the fact that leachate damaged the membrane system of the seeds. By delaying germination, lowering the germination rate of the weeds and inhibiting seedling growth, leachate from E. adenophorum could provide an effective way of controlling the weeds.     

椪柑精油及其主要抑菌组分对菌核青霉的抑制作用

采用水蒸气蒸馏法提取椪柑(Citrus reticulate Blanco)果皮精油,并用GC-MS对其成分进行分析,共鉴定出46种成分,主要包括柠檬烯(57.67%)、β-芳樟醇(5.36%)、2-蒈烯(4.47%)、β-蒎稀(4.31%)、γ-松油烯(4.08%)、α-蒎烯(3.27%)、1,2-二异丙烯基环丁烷(2.87%)、β-月桂烯(2.77%)、α-侧柏烯(2.40%)、β-水芹烯(2.24%)、癸醛(1.80%)和香茅醇(1.49%)等。采用污染食物技术(poisoned food technique)和液体培养法(liquid culture)测定了不同浓度椪柑精油以及主要抑菌组分对菌核青霉的抑制作用。结果表明:不同浓度(0.5~20μl/ml)的椪柑精油对菌核青霉生长均有一定的抑制,且抑菌效果与浓度呈正相关。无论是采用污染食物技术还是液体培养法,20μl/ml椪柑精油均能完全抑制菌核青霉生长;随着培养 时间延长到7d, 20μl/ml椪柑精油抑菌效果有所下降,但仍能显著抑制菌核青霉生长。采用污染食物技术考察了椪柑精油中7种常见抑菌成分对菌核青霉的影响。结果表明,0.04μl/ml柠檬醛和1.07μl/ml β-芳樟醇能显著抑制菌核青霉生长,而其他组分无明显作用。实验结果表明,椪柑精油的抑菌作用可能归功于其所含的柠檬醛和β-芳樟醇。     

解淀粉芽孢杆菌KN-BL-1及其发酵豆粕产抗菌肽类物质的研究

以牛津杯法比较解淀粉芽孢杆菌KN-BL-1及其发酵豆粕的抑菌效果,通过酸沉淀法分离粗多肽,确定产生抑菌效果的为多肽类物质,通过DEAE-Sepharose离子交换层析及Sephadex G-25凝胶过滤层析分离纯化粗多肽以研究其各组分的抑菌效果,并使用4000 Q TRAP液相色谱-质谱联用仪初步确定抗菌肽样品的分子量范围.结果表明,KN-BL-1及其发酵豆粕浸提液对S.aureus等革兰氏阳性菌均有明显的抑菌效果;粗多肽经过层析分离纯化后,三个峰表现抑菌特性,其中有一个抑菌效果最好,抑菌圈清晰,直径为19.8 mm.     

Characteristics and inhibition by flavonoids of 20alpha-hydroxysteroid dehydrogenase activity in mouse tissues

Progesterone was stereoselectively reduced to a metabolite 20alpha-hydroxy-4-pregnen-3-one in the cytosolic fraction from the liver of male mice, indicating that the reduction of progesterone is catalyzed by 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD). The cytosolic 20alpha-HSD activity was observed not only in the liver, but also in the kidney and lung. In liver cytosol, both NADPH and NADH were effective as cofactors for 20alpha-HSD activity, although NADPH was better than NADH for the enzyme activity. On the other hand, 20alpha-HSD activity in kidney cytosol required only NADPH as a cofactor. No significant sex-related difference of 20alpha-HSD activity was observed in liver and kidney cytosols. Flavonoids have been reported to inhibit the biosynthesis and metabolism of steroids. However, little is known about inhibitory effects of flavonoids on 20alpha-HSD activity. Thus, the effects of 16 flavonoids on 20alpha-HSD activity were examined, using liver cytosol of male mice. Among flavonoids tested, fisetin, apigenin, naringenin, luteolin, quercetin and kaempferol exhibited high inhibitory potencies for the 20alpha-HSD activity. We propose the possibility that these flavonoids augment progesterone signaling by inhibiting potently 20alpha-HSD activity in non-reproductive tissues.