微生物降解苯甲酸的研究进展

苯甲酸在工业中的广泛应用使其成为环境中的常见污染物,对微生物好氧降解苯甲酸的邻位途径、间位途径、龙胆酸途径和原儿茶酸途径及厌氧降解途径等进行总结,并对苯甲酸降解过程中发挥重要作用的苯甲酸双加氧酶的种类、不同组分及苯甲酸降解基因和调控基因的基因簇进行介绍,同时展望微生物降解污染物的发展方向。     

酵母内源性海藻糖代谢调控研究进展

作为一种天然稳定剂的双糖,海藻糖(Trehalose)在逆境下对生物体活性的保护功能既吸引了广泛的研究兴趣,也使其具有良好的应用价值和潜力。本文聚焦重要模式微生物和工业应用微生物酵母,结合组学研究最新进展,从海藻糖代谢途径、应激条件下的海藻糖代谢和转录特征以及提高胞内海藻糖含量策略等方面,对内源性海藻糖研究新进展进行了综述。     

生物合成对羟基苯甲酸的研究进展

对羟基苯甲酸(4-Hydroxybenzoate,4HBA)是用途广泛的有机原料,现行的生产工艺是以石油成分合成而得,在环境污染不断恶化、人类生存已经面临威胁之际,开发利用可再生资源的生产工艺已成为全球当务之急。本综述在简要介绍从石油成分合成4HBA之后,主要阐述利用植物和微生物从可再生资源合成4HBA的研究进展。莽草酸途径是生物合成芳香族化合物的重要途径,从该途径的最终产物分支酸到4HBA有两条途径。一条是分支酸裂解酶直接催化分支酸生成4HBA(莽草酸-分支酸路线)。另外一条途径是在植物细胞内引入荧光假单胞菌Pseudomonas fluorescens的对羟基肉桂酸-Co A裂解酶打通从苯丙素合成4HBA的通路(植物苯丙素路线)。最后介绍了一个天然合成积累4HBA的微泡菌Microbulbifer,并对其深入研究进行了展望。     

发酵酒中氨基甲酸乙酯的研究进展

对发酵酒中氨基甲酸乙酯（Ethyl carbamate,EC）的致癌机理、检测方法、形成机制、前驱物质及控制方法等方面进行综述。阐述目前研究进展的同时,对存在问题进行分析并提出解决设想及应用展望。氨基甲酸乙酯可由自然反应及添加前驱物质两种方式形成,其致癌机理是通过两种不同途径破坏DNA结构。通常情况,主要通过减少前体物质的添加和形成抑制氨基甲酸乙酯的生成。氨基甲酸乙酯的通用检测方法为色谱与不同检测器结合使用或色谱与质谱联用,其中,检测前的样品前处理有液液萃取,固相萃取等不同形式。目前,我国检测控制工作虽然已经取得一定进展,但是检测方法不够经济有效,控制方法不能够普遍应用。关于控制方法的最新研究中,基因工程技术与系统生物技术的相关应用纳入进程,后基因组研究和蛋白质学等对基因的应用改造处于探索阶段。随着关于氨基甲酸乙酯的危害、形成机理等方面的研究不断深入,不同机制的控制方法不断出现。EC的处理逐步进入更加完善的状态。     

mhbR和mhbT基因移码突变对3-羟基苯甲酸代谢的影响

Klebsiella pneumoniae M5a1菌株能以3-羟基苯甲酸作为唯一碳源和能源生长,编码分解代谢3-羟基苯甲酸的基因被克隆至-8kb的DNA片段上(pBSI质粒),含有该质粒的大肠杆菌获得了以3-羟基苯甲酸作为唯一碳源和能源生长的能力。经测序并与GenBank中的已知基因产物进行氨基酸同源性比较后,发现其中的mhbR与转录调节基因和mhbT与底物转运基因具有较高同源性,推断可能具有相应的功能。含有mhbR的移码突变子或mhbT的移码突变子的大肠杆菌在底物3-羟基苯甲酸中培养时,其生长速度和代谢速度都较野生型明显缓慢。     

内源性大麻素及其受体在肝硬化领域的研究进展

肝硬化时,内源性大麻素在血液、肝脏、心肌及大脑中表达量增加,通过其受体和其他途径促进肝硬化的发生发展,提示内源性大麻素系统在肝硬化及其并发症中发挥着重要的作用,成为近年来肝硬化药物作用的新靶点,为肝硬化的治疗拓展新的视野,本文就内源性大麻索及其受体在该领域的研究进行综述.     

植物抗病性物质的研究进展

植物与病原菌相互作用后在植物体内会产生抗性物质。植物的抗病性物质包括两大类 :植物固有的抗菌物质和植物保卫素。本文就近年来对植物抗病性物质的化学组成、生物合成、代谢途径方面的研究进行了综述。     

植物抗病性物质的研究进展

植物与病原菌相互作用后在植物体内会产生抗性物质。植物的抗病性物质包括两大类：植物固有的抗菌物质和植物保卫素。本文就近年来对植物抗病性物质的化学组成、生物合成、代谢途径方面的研究进行了综述。     

四川山鹧鸪基因组中内源性逆转录病毒的分析

内源性逆转录病毒(ERV)是插入到宿主基因组中的、可以稳定遗传的病毒基因组,能够在宿主体内表达和复制,调节插入位点附近的基因表达,以及抑制同源病毒的感染。从四川山鹧鸪Arborophila rufipectus基因组中确定了3 962个全长ERV拷贝,其中4个具有完整的结构,72个具有自我复制的能力,554个含有gag、pol或env基因所编码的蛋白质结构域。根据逆转录酶序列的相似性,确定了7个ERV家族,并依据与其他物种的相似性对家族进行了命名。其中,AruERV-L包含122个ERV拷贝,为拷贝数最多的家族。7个ERV家族的年龄分布在0～12百万年,其中AruERV-K1是最年轻的家族,其约86%的拷贝年龄在1百万年以内。     

微生物发酵产二十二碳六烯酸代谢机理的研究进展

二十二碳六烯酸(简称DHA)是一种重要的长链多不饱和脂肪酸,对人体具有重要的生理功能。微生物发酵生产的DHA与鱼油来源的DHA相比,具有诸多优点,其发展前景广阔。以下从发酵菌株、代谢途径、关键酶以及油脂积累机制等方面进行了综述,为通过代谢工程等技术手段进一步提高DHA产量提供了参考。     

维生素C生物转化的代谢工程研究

本从代谢工程角度出发,综述维生素C(Vc)生物转化代谢研究进展。分别论述了3条产生Vc重要前体2-酮基-L-古龙酸(2-KLG)反应路线的代谢机制、反应酶系及代谢工程菌构建等方面的问题;并对Vc生物转化应用前景作了展望。     

Circadian changes in endogenous concentrations of indole-3-acetic acid,melatonin, serotonin,abscisic acid and jasmonic acid in Characeae (Chara australis Brown)

Giant-celled Characeae (Chara australis Brown), grown for 4 months on 12/12 hr day/night cycle and summer/autumn temperatures, exhibited distinct concentration maxima in auxin (indole-3-acetic acid; IAA), melatonin and serotonin about 4 hr after subjective daybreak. These concentration peaks persisted after 3 day pretreatment in continuous darkness: confirming a circadian rhythm, rather than a response to “light on.” The plants pretreated for 3 d in continuous light exhibited several large IAA concentration maxima throughout the 24 hr. The melatonin and serotonin concentrations decreased and were less synchronized with IAA. Chara plants grown on 9/15 hr day/night cycle for 4 months and winter/spring temperatures contained much smaller concentrations of IAA, melatonin and serotonin. The IAA concentration maxima were observed in subjective dark phase. Serotonin concentration peaks were weakly correlated with those of IAA. Melatonin concentration was low and mostly independent of circadian cycle. The “dark” IAA concentration peaks persisted in plants treated for 3 d in the dark. The plants pretreated for 3 d in the light again developed more IAA concentration peaks. In this case the concentration maxima in melatonin and serotonin became more synchronous with those in IAA. The abscisic acid (ABA) and jasmonic acid (JA) concentrations were also measured in plants on winter regime. The ABA concentration did not exhibit circadian pattern, while JA concentration peaks were out of phase with those of IAA. The data are discussed in terms of crosstalk between metabolic pathways.     

Determination of dopamine in the presence of ascorbic acid using poly(3,5-dihydroxy benzoic acid) film modified electrode

A polymerized film of 3,5-dihydroxy benzoic acid (DBA) was prepared on the surface of a glassy carbon electrode (GCE) in neutral solution by cyclic voltammetry (CV). The poly(DBA) film-coated GCE exhibited excellent electrocatalytic activity toward the oxidation of dopamine (DA). A linear range of 1.0 × 10⁻⁷ to 1.0 × 10⁻⁴ M and a detection limit of 6.0 × 10⁻⁸ M were observed in pH 7.4 phosphate buffer solutions. Moreover, the interference of ascorbic acid (AA) was effectively eliminated. This work provides a simple and easy approach to selective detection of DA in the presence of AA.     

调控肺部炎症消退的内源性介质

炎症反应是宿主重要防御机制之一。慢性炎症或过度炎症反应可导致严重的肺部疾病,如哮喘、急性呼吸窘迫综合征等。新近研究表明炎症消退是一个主动过程,炎症的及时消退是防止炎症过强及走向慢性化的关键环节。因此,调控炎症消退的内源性介质成为新的研究热点。促进炎症消退内源性介质的发现不仅为肺部疾病研究提供新视野,也为全新的促炎症消退治疗策略防治肺部疾病提供理论依据。     

Docking of oxalyl aryl amino benzoic acid derivatives into PTP1B

Protein Tyrosine Phosphatases (PTPs) that function as negative regulators of the insulin signaling cascade have been identified as novel targets for the therapeutic enhancement of insulin action in insulin resistant disease states. Reducing Protein Tyrosine Phosphatase1B (PTP1B) abundance not only enhances insulin sensitivity and improves glucose metabolism but also protects against obesity induced by high fat feeding. PTP1B inhibitors such as Formylchromone derivatives, 1, 2-Naphthoquinone derivatives and Oxalyl aryl amino benzoic derivatives may eventually find an important clinical role as insulin sensitizers in the management of Type-II Diabetes and metabolic syndrome. We have carried out docking of modified oxalyl aryl amino benzoic acid derivatives into three dimensional structure of PTP1B using BioMed CAChe 6.1. These compounds exhibit good selectivity for PTP1B over most of phosphatases in selectivity panel such as SHP-2, LAR, CD45 and TCPTP found in literature. This series of compounds identified the amino acid residues such as Gly220 and Arg221 are important for achieving specificity via H-bonding interactions. Lipophilic side chain of methionine in modified oxalyl aryl amino benzoic acid derivative [1b (a2, b2, c1, d)] lies in closer vicinity of hydrophobic region of protein consisted of Meth258 and Phe52 in comparison to active ligand. Docking Score in [1b (a2, b2, c1, d)] is -131.740Kcal/mol much better than active ligand score -98.584Kcal/mol. This information can be exploited to design PTP1B specific inhibitors.     

Reconstruction of pathways associated with amino acid metabolism in human mitochondria

We have used a bioinformatics approach for the identification and reconstruction of metabolic pathways associated with amino acid metabolism in human mitochondria. Human mitochondrial proteins determined by experimental and computational methods have been superposed on the reference pathways from the KEGG database to identify mitochondrial pathways. Enzymes at the entry and exit points for each reconstructed pathway were identified, and mitochondrial solute carrier proteins were determined where applicable. Intermediate enzymes in the mitochondrial pathways were identified based on the annotations available from public databases, evidence in current literature, or our MITOPRED program, which predicts the mitochondrial localization of proteins. Through integration of the data derived from experimental, bibliographical, and computational sources, we reconstructed the amino acid metabolic pathways in human mitochondria, which could help better understand the mitochondrial metabolism and its role in human health.     

Effects of m-Cl-peroxy benzoic acid on glycolysis in Saccharomyces cerevisiae

Concentrations of m-Cl-peroxy benzoic acid (CPBA) higher than 0.1 mM decrease the ATP-content of Saccharomyces cerevisiae in the presence of glucose in 1 min to less than 10% of the initial value. In the absence of glucose, 1.0 mM CPBA is necessary for a similar effect. After the rapid loss of ATP in the first min in the presence of glucose caused by 0.2 mM CPBA, the ATP-content recovers to nearly the initial value after 10 min. Aerobic glucose consumption and ethanol formation from glucose are both completely inhibited by 1.0 mM CPBA. Assays of the activities of nine different enzymes of the glycolytic pathway as well as analysis of steady state concentrations of metabolites suggest that glyceraldehyde-3-phosphate dehydrogenase is the most sensitive enzyme of glucose fermentation. Phosphofructokinase and alcohol dehydrogenase are slightly less sensitive. Incubation for 1 or 10 min with concentrations of 0.05 to 0.5 mM CPBA causes a) inhibition of glyceraldehyde-3-phosphate dehydrogenase, b) decrease of the ATP-content and c) a decrease of the colony forming capacity. From these findings it is concluded that the disturbance of the ATP-producing glycolytic metabolism by inactivation of glyceraldehyde-3-phosphate dehydrogenase may be an explanation for cell death caused by CPBA.Abbreviations CPBA m-Chloro-peroxy benzoic acid - G-6-P glucose-6-phosphate - F-6-P fructose-6-phosphate - F-1,6-P₂ frnctose-1,6-bisphosphate - DAP dihydroxyacetone phosphate - GAP glyceraldehyde-3-phosphate - 2PGA 2-phosphoglycerate - PEP phosphoenol pyruvate - Pyr pyruvate - EtOH ethanol - PFK phosphofructokinase - GAPDH glyceraldehyde-3-phosphate dehydrogenase - ADH alcohol dehydrogenase Dedicated to Prof. Dr. Wolfgang Gerok at the occasion of his 60th birthday     

Adaptive spatial biases in nectar deposition in the nests of honey bees

Honey bees store their large supply of honey at the top and, to a lesser extent, along the edges of their nests. Whether this pattern is the result of preferences for where nectar is deposited is unclear. Camazine, in a path breaking study of pattern formation, found evidence that workers deposit nectar at random, while Free and Williams in an earlier study found evidence that bees prefer to deposit nectar into particular types of comb. Here we reexamine this question. We tested three hypotheses, all of which posit that bees have adaptive biases which allow them to deposit nectar directly into the most useful locations. We found that bees have preferences for depositing nectar into cells at the top of the nest, into old vs. new comb, and into interior facing comb vs. comb facing the exterior environment. These preferences may ensure that nectar is placed directly into those regions where it will ultimately be stored. They may also result in an optimal pattern of comb usage with respect to brood rearing. This work, along with the results of previous studies, suggests that comb usage patterns may reflect competing selective pressures and be more complicated than previously thought. Received 17 May 2007; revised 15 June 2007; accepted 3 July 2007.     

Hippuric acid and benzoic acid inhibition of urine derived N2O emissions from soil

Atmospheric concentrations of the greenhouse gas nitrous oxide (N₂O) have continued to rise since the advent of the industrial era, largely because of the increase in agricultural land use. The urine deposited by grazing ruminant animals is a major global source of agricultural N₂O. With the first commitment period for reducing greenhouse gas emissions under the Kyoto Protocol now underway, mitigation options for ruminant urine N₂O emissions are urgently needed. Recent studies showed that increasing the urinary concentration of the minor urine constituent hippuric acid resulted in reduced emissions of N₂O from a sandy soil treated with synthetic bovine urine, due to a reduction in denitrification. A similar effect was seen when benzoic acid, a product of hippuric acid hydrolysis, was used. This current laboratory experiment aimed to investigate these effects using real cow urine for the first time. Increased concentrations of hippuric acid or benzoic acid in the urine led to reduction of N₂O emissions by 65% (from 17% to <6% N applied), with no difference between the two acid treatments. Ammonia volatilization did not increase significantly with increased hippuric acid or benzoic acid concentrations in the urine applied. Therefore, there was a net reduction in gaseous N loss from the soil with higher urinary concentrations of both hippuric acid and benzoic acid. The results show that elevating hippuric acid in the urine had a marked negative effect on both nitrification and denitrification rates and on subsequent N₂O fluxes. This study indicates the potential for developing a novel mitigation strategy based on manipulation of urine composition through ruminant diet.     

Blastoderm development in honey bee embryogenesis as seen in the scanning electron microscope

Summary

Based on observations in the scanning electron microscope, we describe the successive changes at the cell surface of fertilized honey bee eggs which, over a period of 20 h, lead to blastoderm formation. Each change starts in the differentiation center located in the anterior egg half and from there spreads as a wave towards both poles. However, one of the waves is heterogeneous: the protrusions or caps of oolemma which start enveloping the preblastoderm nuclei arise in different ways in the anterior third and in the more posterior regions of the egg cell. After the formation of these protrusions, three mitotic waves pass over the peripheral nuclei. The last of these blastemal mitoses results in a two-layered arrangement of peripheral nuclei, each surrounded by an outpocketing of the egg cell basally confluent with the central yolky part. This two-layered state after some time transforms into a single layer of columnar outpocketings which increase in height by extending their borders centripetally into the secondary periplasm (inner ‘Keimhautblastem’). The outpocketings disconnect from the central yolk mass as separate blastoderm cells only a short time before gastrulation. The events described here consume nearly 40% of the time period between oviposition and hatching; thus, and by comparison with most other insects, blastoderm formation in the honey bee is a very lengthy process.