Specific Inhibitors of Ammonia Oxidation in Nitrosomonas

The following compounds or treatments have been shown to inhibit the oxidation of ammonia, but not the oxidation of hydroxylamine in cells of Nitrosomonas: (i) metal-binding agents such as allylthiourea or potassium cyanide; (ii) compounds such as SKF 525 which interact with cytochrome P-450 of mammalian microsomes; (iii) carbon monoxide; (iv) inhibitors of catalase, peroxidase, and amine oxidases such as thiosemicarbazide, ethylxanthate, and iproniazid, respectively; (v) uncouplers of oxidative phosphorylation such as m-chlorocarbonylcyanidephenylhydrazone; (vi) electron acceptors such as phenazine methosulfate; (vii) compounds such as methanol or N(2)O which react with free radicals; and (viii) illumination with 420 lux (5,000 foot candles) of light.     

Recent advances in the fight against leishmaniasis with natural products

The active compounds obtained from some medicinal plants used traditionally worldwide for the treatment of leishmaniasis are reviewed. Among these active molecules, described in recent literature are quinoline alkaloids such as alkyl-2 quinoline and aryl-2 quinoline from Galipea longiflora, isoquinoline alkaloids such as isoguattouregidine from Guatteria foliosa, indole alkaloids such as conodurine and gabunine from Pescheiera van heurkii, terpenes such as jatrogrossidione from Jatropha grossidentata, acetogenins such as senegalene from Annona senegalensis and lignans such as (+)nyasol from Asparagus africanus. Other natural compounds with antileishmanial activity are coumarins, chalcones, lactones, tetralones and saponins. Some of them are known antiprotozoal natural products. These compounds could be used as templates to discover new and effective drugs against leishmaniasis.     

Profiling for novel proteomics biomarkers in neurodevelopmental disorders

Protein biomarker discovery from biological fluids, such as serum, has been widely applied to disorders such as cancer and has more recently also been utilized in neuro-psychiatric disorders with relatively clear biological causes, such as Alzheimer's disease and schizophrenia. The application of the associated technologies for the identification of protein biomarker signatures in neurodevelopmental disorders, such as autism spectrum disorder and attention deficit hyperactivity disorder, is comparatively less well established. The aim of this article is to provide an overview of the various protocols available for such analysis, discuss reports in which these techniques have been previously applied in biomarker discovery/validation in neurodevelopmental disorders, and consider the future development of this area of research.     

Coastal sand mining of heavy mineral sands: Contestations,resistance, and ecological distribution conflicts at HMS extraction frontiers across the world

Coastal sand mining for metals involves extraction of heavy mineral sands (HMS), which are sedimentary deposits of dense minerals that accumulate in coastal environments. HMS are localized concentrations of ores such as ilmenite, rutile, leucoxene, and iron, which are sources of metals such as titanium, zircon, iron, sillimanite/kyanite, staurolite, monazite, and garnet. The applications of these metals range from everyday products such as ceramics, paint, and pigments, as well as technologically advanced applications in the airline, shipbuilding, medicine, and defense industries. HMS extraction implies strip mining of coastal areas, which are often unique biodiversity ecosystems, or fragile ecosystems built up on sandy soils or dunes. The loss of such spaces has impacts such as loss of biodiversity and habitats, salt-water intrusion into agricultural lands and increased exposure to sea level rise. As a result of the serious ecological and socioeconomic transformations at such extraction frontiers, these operations cause resistance movements across the world. This article identifies and documents 24 cases of resistance against such operations. It presents the first comprehensive database and analysis of HMS related ecological distribution conflicts.     

Regression with frailty in survival analysis

In studies of survival, the hazard function for each individual may depend on observed risk variables but usually not all such variables are known or measurable. This unknown factor of the hazard function is usually termed the individual heterogeneity or frailty. When survival is time to the occurrence of a particular type of event and more than one such time may be obtained for each individual, frailty is a common factor among such recurrence times. A model including frailty is fitted to such repeated measures of recurrence times.     

The ever-changing brain: cellular and molecular mechanisms for the effects of stressful experiences

The adult brain is capable of considerable structural and functional plasticity and the study of hormone actions in brain has contributed to our understanding of this important phenomenon. In particular, stress and stress-related hormones such as glucocorticoids and mineralocorticoids play a key role in the ability of acute and chronic stress to cause reversible remodeling of neuronal connections in the hippocampus, prefrontal cortex, and amygdala. To produce this plasticity, these hormones act by both genomic and non-genomic mechanisms together with ongoing, experience-driven neural activity mediated by excitatory amino acid neurotransmitters, neurotrophic factors such as brain derived neurotrophic factor, extracellular molecules such as neural cell adhesion molecule, neuropeptides such as corticotrophin releasing factor, and endocannabinoids. The result is a dynamic brain architecture that can be modified by experience. Under this view, the role of pharmaceutical agents, such as antidepressants, is to facilitate such plasticity that must also be guided by experiences.     

On the rotational brownian motion of a bacterial idle motor. I. Theory of time-dependent fluorescence depolarization

A rotational diffusion equation and its Green's function for a spheroidal particle such as a bacterial body, to which an actively driving but idle motor is attached, are presented. As an application of the theory, general expressions for the time-dependent fluorescence depolarization caused by such a particle have been obtained. Measurement of such depolarizalion should provide a useful tool for determination of the rate of revolution of the rotating motor attached to cell bodies such as bacteria under various solution conditions, if a fluorescent (or phosphorescent) label is attached to the motor shaft.     

Chemical factors influencing adsorption of bacteriophage MS2 to membrane filters.

Antichaotropic salts, such as magnesium sulfate, and metal chelators, such as citrate ions, promoted adsorption of bacteriophage MS2 to membrane filters. In contrast, compounds that disrupt hydrophobic interactions, such as chaotropic salts, urea, Tween 80, and ethanol, did not promote adsorption of MS2 to membrane filters and counteracted the ability of magnesium sulfate to promote such adsorption. These results provide evidence that magnesium sulfate promotes the association of MS2 with membrane filters primarily by strengthening hydrophobic interactions between the virus and the filters.     

叶绿体转基因植物——一种新型生物反应器

叶绿体转基因植物作为生物反应器, 具有外源蛋白表达量高和环境安全性好等优点, 近年来呈现出诱人的发展前景。本文综述了叶绿体基因工程的优越性, 并重点介绍了叶绿体转基因植物作为生物反应器在生产疫苗、药用蛋白及生物可降解塑料等物质方面的最新研究进展。     

Effect of kosmotropicity of ionic liquids on the enzyme stability in aqueous solutions

This paper examined the effect of several pyridinium and imidazolium-based ionic liquids (ILs) on the protease stability in aqueous solutions. In general, the enzyme was found quite active at low concentrations of hydrophilic ILs. In aqueous environment, the enzyme was stabilized by the kosmotropic anions (such as CF3COO- and CH3COO-) and chaotropic cations (such as [BuPy]+ and [EMIM]+), but was destabilized by chaotropic anions (such as tosylate and BF4-) and kosmotropic cations (such as [BMIM]+).     

The reliability of relative anion-cation permeabilities deduced from reversal (Dilution) potential measurements in ion channel studies

Measurements of anion-cation permeability ratios (e.g., P _Cl/P _Na) are most readily made by measuring changes in zero-current reversal potential when the salt concentration on one side of the membrane (e.g., external NaCl) is decreased. This is particularly useful for measuring changes in ion selectivity in wild-type and mutant channels, such as those of the ligand-gated ion channel superfamily, and has shown that many of these channels have a significant permeability to counter-ions. One Brownian dynamics study of ion permeation through such narrow ion channels failed to observe such counter-ion movement, although later, another Brownian dynamics study did observe counter-ion movement through simulations of the same channels. The question has been raised as to the reliability of such reversal potential measurements for determining permeability ratios, particularly given the use of an equation such as the Goldman-Hodgkin-Katz (GHK) equation, which is often used to calculate such ratios. A new derivation of the GHK equation in terms of activity coefficients is also included. The application of irreversible thermodynamics will be shown to qualitatively support the reliability of such experimental anion-cation permeability values derived from reversal potential measurements. It will then be shown that for such zero-current situations, different electrodiffusion models, with very different underlying assumptions, produce almost identical relative permeabilities (and reversal potentials). Finally, the results of the two Brownian dynamics simulation studies and the relationship between reversal potentials and relative permeability will be discussed.     

DNA-cyclodextrin composite material for environmental applications

Recently, we prepared water-insoluble and nuclease-resistant DNA films by UV irradiation. The DNA films accumulated the harmful DNA-intercalating compounds, such as ethidium bromide and acridine orange. Additionally, the water-insoluble DNA films bound endocrine disruptors that had planar structures, such as dioxin derivatives, polychlorobiphenyl (PCB) derivatives, and benzo[a]pyrene. However, other harmful endocrine disruptors that lack a planar structure, such as bisphenol A and diethylstilbestrol, did not bind the water-insoluble DNA films. Therefore, we prepared the DNA-cyclodextrin composite material by mixing the DNA and the cyclodextrin-immobilized poly(allylamine) (PCD). As a result, these composite materials had properties of both the double-stranded DNA, such as intercalation, and the cyclodextrin, such as encapsulation of an organic molecule into the intramolecular cavity. Therefore, these materials could accumulate not only the harmful compounds with planar structures but also the nonplanar molecules, such as bisphenol A, diethylstilbestrol, and nonylphenol. These DNA-PCD composite materials may have the potential to be novel environmental materials that absorb harmful compounds.     

Metabolic cycles as an underlying basis of biological oscillations

The evolutionary origins of periodic phenomena in biology, such as the circadian cycle, the hibernation cycle and the sleep-wake cycle, remain a mystery. We discuss the concept of temporal compartmentalization of metabolism that takes place during such cycles, and suggest that cyclic changes in a cell's metabolic state might be a fundamental driving force for such biological oscillations.     

Volatile compounds of headspace gas in the Japanese fish sauce ishiru

Volatile compounds from the headspace gas of ten brands of the Japanese fish sauce ishiru were analyzed by GC-MS with a thermal-desorption cold-trap system. Many volatile peaks were detected and 51 compounds were identified. The major volatile compounds in ishiru included aldehydes (such as 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, and benzaldehyde), nitrogen-containing compounds (such as pyrazine derivatives and trimethylamine), sulfur-containing compounds (such as dimethyl disulfide), and ketones (such as 2-butanone and 3-methyl-2-butanone). On the other hand, volatile fatty acids were nearly absent in the headspace gas of ishiru.     

Multirate state and parameter estimation in an antibiotic fermentation with delayed measurements

This article discusses issues related to estimation and monitoring of fermentation processes that exhibit endogenous metabolism and time-varying maintenance activity. Such culture-related activities hamper the use of traditional, software sensor-based algorithms, such as the extended kalman filter (EKF). In the approach presented here, the individual effects of the endogenous decay and the true maintenance processes have been lumped to represent a modified maintenance coefficient, m(c). Model equations that relate measurable process outputs, such as the carbon dioxide evolution rate (CER) and biomass, to the observable process parameters (such as net specific growth rate and the modified maintenance coefficient) are proposed. These model equations are used in an estimator that can formally accommodate delayed, infrequent measurements of the culture states (such as the biomass) as well as frequent, culture-related secondary measurements (such as the CER). The resulting multirate software sensor-based estimation strategy is used to monitor biomass profiles as well as profiles of critical fermentation parameters, such as the specific growth for a fed-batch fermentation of Streptomyces clavuligerus. (c) 1994 John Wiley & Sons, Inc.     

Human genetic banking: altruism, benefit and consent

This article considers how we should frame the ethical issues raised by current proposals for large-scale genebanks with on-going links to medical and lifestyle data, such as the Wellcome Trust and Medical Research Council's 'UK Biobank'. As recent scandals such as Alder Hey have emphasised, there are complex issues concerning the informed consent of donors that need to be carefully considered. However, we believe that a preoccupation with informed consent obscures important questions about the purposes to which such collections are put, not least that they may be only haphazardly used for research (especially that of commercial interest)--an end that would not fairly reflect the original altruistic motivation of donors, and the trust they must invest. We therefore argue that custodians of such databases take on a weighty pro-active duty, to encourage public debate about the ends of such collections and to sponsor research that reflects publicly agreed priorities and provides public benefits.     

Activation of protein kinase C by ganglioside GM3 in the presence of calcium and 12-O-tetradecanoylphorbol-13-acetate

Ganglioside GM3 and 12-O-tetradecanoylphorbol-13-acetate activated protein kinase C as substitutes for phosphatidylserine and diacylglycerol. Hydrophobic gangliosides such as GM4 and GM3 were rather more potent activators of protein kinase C than hydrophilic ones such as GD1a and GT1b. Active tumor promoters such as teleocidin, mezerein, phorbol 12,13-acetate and phorbol 12,13-dibenzoate also activated protein kinase C, but not inactive tumor promoters such as phorbol and 4-alpha-phorbol 12,13-didecanoate.     

基质金属蛋白酶

基质金属蛋白酶是一类分解细胞外基质组分的锌蛋白酶⒚它们在有机体生长发育中的细胞外基质逆转与重塑以及疾病中的病理损害起着极为重要的作用⒚基质金属蛋白酶的表达和活性在不同细胞水平受到严密调控,如细胞因子、生长因子以及激素的调节⒚基质金属蛋白酶以酶原形式分泌,随后被其它蛋白酶如胞浆素或非蛋白酶类化学物质如有机汞所激活⒚所有基质金属蛋白酶都受到天然抑制剂 金属蛋白酶组织抑制剂所抑制⒚两者的不平衡导致许多疾病的发生,如肿瘤侵入及转移⒚合成基质金属蛋白酶组织抑制剂所抑制,如 Ｍ ａｒｉｍ ａｓｔａｔ 能控制肿瘤转移的发生及进一步扩散⒚本文将对基质金属蛋白酶的特征、分子区域结构、底物特性、激活机制、调控方式等方面进行最新概述⒚     

Elucidating mechanistic principles underpinning eukaryotic translation initiation using quantitative fluorescence methods

Eukaryotic translation initiation is an intricate process involving at least 11 formally classified eIFs (eukaryotic initiation factors), which, together with the ribosome, comprise one of the largest molecular machines in the cell. Studying such huge macromolecular complexes presents many challenges which cannot readily be overcome by traditional molecular and structural methods. Increasingly, novel quantitative techniques are being used to further dissect such complex assembly pathways. One area of methodology involves the labelling of ribosomal subunits and/or eIFs with fluorophores and the use of techniques such as FRET (F?rster resonance energy transfer) and FA (fluorescence anisotropy). The applicability of such techniques in such a complex system has been greatly enhanced by recent methodological developments. In the present mini-review, we introduce these quantitative fluorescence methods and discuss the impact they are beginning to have on the field.