High rate anaerobic digestion of a petrochemical wastewater using biomass support particles

Anaerobic digestion of wastewater from a dimethyl terephthalate plant was studied in continuously stirred tank reactors with plastic net biomass support particles (BSP) at a level of 20% (v/v). The experimental results showed that the BSP system could treat the wastewater at a hydraulic retention time as low as 1.5 d, organic loading as high as 20 kg COD/m3/d and at acidic feed pH as low as 4.5 with 95% COD reduction and biogas production of about 8l/l/d, while the control system without support particles could not treat the wastewater above a 5-d hydraulic retention time, 5 kg COD/m3/d organic loading and a feed pH of 6.0. Thus, augmentation of BSP upgraded the performance of the conventional suspended growth system to an equivalent level to advanced reactors.     

Inorganic nitrogen regulation of glutamate uptake in the cyanobacterium Nostoc muscorum

In Nostoc muscorum (Anabaena ATCC 27893) glutamate was not metabolised as a fixed nitrogen source, rather it functioned as an inhibitor of growth. The latter effect was nitrogen source specific and occurred in N₂-fixing cultures but not in cultures assimilating nitrate or ammonium. NO₃^--grown cultures lacked heterocysts and nitrogenase activity and showed a nearly 50% reduction in glutamate uptake rates, as well as in the final extent of glutamate taken up, compared to N₂-fixing or nitrogen-limited control cultures. NH₄⁺-grown cultures showed a similar response, except that the reduction in glutamate uptake rates and the final exten of glutamate taken up was over 80%. The present results suggest a relation between nitrate/ammounium nitrogen-dependent inhibition of glutamate uptake, probably via repression of the glutamate transport system, and glutamate toxicity.     

盐及干旱胁迫对油菜抗氧化系统和RbohC、RbohF基因表达的影响

以白菜型油菜‘陇油6号’和‘天油2号’为试验材料,经MAPK抑制剂U0126、H_2O_2清除剂DMTU、NADPH氧化酶抑制剂DPI和IMD预处理后再分别进行盐胁迫、PEG-6000模拟干旱胁迫,研究其对两种油菜幼苗活性氧、抗氧化酶活性和RbohC、RbohF基因表达的影响.结果表明:盐胁迫和PEG-6000模拟干旱胁迫下,两种白菜型油菜中H_2O_2积累量上升,O_2^-·积累量下降,抗氧化酶(超氧化物歧化酶SOD、过氧化氢酶CAT、抗坏血酸过氧化物酶APX和谷胱甘肽还原酶GR)活性和RbohC、RbohF基因表达均升高.与单独胁迫处理相比,两种油菜O_2^-·积累、抗氧化酶活性和RbohC、RbohF基因的表达量均明显降低,经DMTU、DPI和IMD预处理后再分别进行盐和干旱胁迫,H_2O_2积累量下降,但U0126预处理后再进行胁迫处理,H_2O_2积累量上升.说明NADPH氧化酶、MAP激酶级联途径、H_2O_2参与了盐、干旱胁迫下活性氧产生、抗氧化酶活性变化和RbohC、RbohF基因表达的调控.     

Sodium bioenergetics in methanogens and acetogens

Abstract Recent investigations with Methanosarcina barkeri elucidated the role of sodium ions in the energy metabolism of methanogenic bacteria and provided evidence for a novel mechanism of energy transduction with Na⁺ as the coupling ion. During methanogenesis from methanol, an eletrochemical sodium gradient generated by a Na⁺/H⁺ antiporter is used as the driving force for the thermodynamically unfavourable oxidation of methanol to the formal redox level of formaldehyde. During methanogenesis from H₂+ CO₂, the reverse reaction, the reduction of formaldehyde to the level of methanol, is accompanied by a primary, electron transport-driven sodium extrusion. Acetogenesis from H₂+ CO₂ as carried out by Acetobacterium woodii is a sodium-dependent process and is accompanied by the generation of a transmembrane sodium gradient with the reduction of formaldehyde to the level of methanol as the sodium-dependent step.     

Amino-functionalized zirconocene (C5H4CH(Me)NMe2)2ZrCl2, a catalyst for the dehydropolymerization of PhSiH3: Probing of peripheral substituent effects on catalyst dehydropolymerization activity

The amino-functionalized metallocene (C₅H₄CH(Me)NMe₂)₂ZrCl₂, [(Cp^N)₂ZrCl₂] was synthesized by salt metathesis of ZrCl₄ and 2 equiv. of C₅H₄CH(Me)NMe₂Li. The metallocene was obtained in good yield as a mixture of rac and meso diastereomers as established by NMR spectroscopy. The addition of 2 equiv. of n-BuLi to the metallocene (Cp^N)₂ZrCl₂ produced a co-catalyst system which was active, at a 1.0 mol% loading, in the dehydropolymerization of PhSiH₃ to poly(phenylsilane), PPSi. The PPSi was obtained as a 9:1 linear–cyclic mixture (M_w=3850, M_n=2300) as established by GPC analysis; ²⁹Si{¹H} NMR spectroscopy revealed an atactic polymer microstructure.     

A mechanistic model for photosynthesis based on the multisubstrate ordered reaction of ribulose 1,5 bisphosphate carboxylase

Abstract. A mechanistic model of photosynthesis is developed based on the characteristics of ribulose 1,5-bisphosphate (RuBP) carboxylase and the assimilation of CO₂ as an ordered reaction with RuBP binding before CO₂. An equation is derived which considers the effects of light (for regeneration of RuBP) and CO₂. Taking values for the maximum turnover of RuBP carboxylase at substrate saturation, the maximum carboxylation efficiency (maximum increase in rate per increase in CO₂ concentration) and the minimum quantum requirement for the C₃ pathway, photosynthesis in the absence of photorespiration is simulated. In the model, at varying concentrations of CO₂, the efficiency of light utilization approaches a maximum value as photon flux density decreases. Similarly, with a given maximum carboxyation capacity, at varying photon flux densities the carboxylation efficiency approaches a constant maximum value (equal to V _max/ K _{m CO2}) as CO₂ is decreased. However, a decrease in the state of activation of RuBP carboxylase under low light results in a lower carboxylation efficiency. Limits on the rate of photosynthesis, as the maximum capacity for regeneration of RuBP is reduced relative to carboxylation potential, or as the maximum capacity of the carboxylase varies, are considered.     

A new dominant selectable marker for genetic transformation; Hsp70-opd

New P element plasmids containing the organophosphate-degrading gene opd as a dominant selectable marker were tested as transformation vectors in Drosophila melanogaster. One of these vectors was modified by the addition of the D. melanogaster mini-white gene as a comarker. When transformed individuals were identified using paraoxon selection for opd alone, results were similar to those obtained with mini-white. No false positives were recovered, however one strain contained the mini-white gene but inadequate resistance to survive our screening regimen due to a defective Hsp70-opd gene. Results suggest that Hsp70-opd is similar to mini-white for distinguishing transformed individuals, but does not require time-consuming individual examination. Due to the mode of action of organophosphorus nerve agents, Hsp70-opd has potential as a selectable marker in numerous animals beside fruit flies.     

A phylogenetic study of the free-living amoeba

Immunological distances were determined for four strains of the free-living amoeba classified as Amoeba proteus, two strains classified as Polychaos dubia and a single strain classified as Chaos carolinensis. The data show that the _ShP strain does not belong to the proteus group; that A. proteus is more closely related to C. carolinensis and is derived from Chaos as is the _ShP strain; that P. dubia and C. carolinensis are the more distantly related species and appear to be the first of the above to have diverged from a common ancestor; and that the amoebae have a long evolutionary history. The accuracy of the phylogenetic tree and the distance Wagner network was discussed. Since the amoebae may be polyphyletic in origin, the latter was assumed to be a more accurate representation of the immunological distance data.     

Role of abscisic acid in a Ca2+ second messenger system

Owen, J. H. 1988. Role of abscisic acid in a Ca²⁺ second messenger system. - Physiol. Plant. 72:637–641.
Recent investigations have shown that Ca²⁺ acts as a second messenger in plant cell coupling of response to stimulus. Data now suggests that abscisic acid (ABA) plays a role as Ca²⁺'agonist' in this Ca²⁺ messenger system, although the molecular basis of such an interaction has not yet been fully investigated. ABA appears to possess a universal Ca²⁺'agonist' role because it elicits responses in systems as diverse as mammalian contractile tissue and cyanobacteria. ABA may therefore be of a wider biological significance than previously recognised.     

Specific effect of manganese on the allantoinase of Vigna Radiata

Vigna radiata seedlings germinated in the presence of Mn²⁺ show an unusual increase in allantoinase activity which is proportional to Mn²⁺ concentration up to 5 mM. Though Mn²⁺ is not an activator for V. radiata allantoinase, it specifically protects allantoinase against thermal as well as papain-catalysed inactivation. Evidence is presented to show that the primary effect of Mn²⁺ is a protective one, both in vitro and in vivo, and that this is reflected in the observed enhancement of allantoinase activity in Mn²⁺ grown seedlings. That this unusual effect of Mn²⁺ is a specific one is indicated by the lack of a similar effect with Mg²⁺. Cu²⁺ is shown to destabilize V. radiata allantoinase in vitro as well as in vivo.     

基于叶干质量比的杉木比叶面积估算模型的构建

随着叶片功能性状研究的不断深入, 通过简单易测量的叶片指标, 同时探究植物生活史权衡对策和估算林分生产力的研究需求日益增长, 例如叶干质量比(LDMC)和比叶面积(SLA)的相互转换。杉木(Cunninghamia lanceolata)是亚热带重要的常绿针叶树种, 基于LDMC对杉木SLA进行估算, 能够为核算SLA提供途径, 为机理解释和生产估算构建连接途径, 为小区域到大尺度、精算到估算搭建桥梁。该研究在湖南会同和河南信阳两个杉木生长区, 对处于不同小生境(坡向、坡位和冠层深度)以及不同生活史(林龄和叶龄)的叶片进行抽样和采集, 通过测得不同叶龄的单叶LDMC和SLA, 初步探究在不同因子下两个性状值的分布差异, 进一步基于LDMC构建SLA估算模型并讨论以叶龄为差分因子对模型的影响。结果表明: 1)杉木SLA平均值为(103.15 ± 69.54) cm ²·g ^-1, LDMC为0.39 ± 0.11; 2)杉木LDMC和SLA可用非线性模型进行估算, 模型符合估算要求; 3)其中一年生叶的拟合效果最好, 老叶(大于二年生叶)的拟合优度较低, 老叶较低的SLA (52.28-75.74 cm ²·g ^-1)可能暗示LDMC的变化保持相对独立性。该研究基于杉木LDMC的SLA估算模型可信且有效, 且不同叶龄对LDMC和SLA的影响可能预示着杉木叶片的响应敏感性和生活史权衡策略。     

盐及干旱胁迫对油菜抗氧化系统和RbohC、RbohF基因表达的影响

以白菜型油菜‘陇油6号’和‘天油2号’为试验材料,经MAPK抑制剂U0126、H₂O₂清除剂DMTU、NADPH氧化酶抑制剂DPI和IMD预处理后再分别进行盐胁迫、PEG-6000模拟干旱胁迫,研究其对两种油菜幼苗活性氧、抗氧化酶活性和RbohC、RbohF基因表达的影响.结果表明: 盐胁迫和PEG-6000模拟干旱胁迫下,两种白菜型油菜中H₂O₂积累量上升,O₂^-·积累量下降,抗氧化酶(超氧化物歧化酶SOD、过氧化氢酶CAT、抗坏血酸过氧化物酶APX和谷胱甘肽还原酶GR)活性和RbohC、RbohF基因表达均升高.与单独胁迫处理相比,两种油菜O₂^-·积累、抗氧化酶活性和RbohC、RbohF基因的表达量均明显降低,经DMTU、DPI和IMD预处理后再分别进行盐和干旱胁迫,H₂O₂积累量下降,但U0126预处理后再进行胁迫处理,H₂O₂积累量上升.说明NADPH氧化酶、MAP激酶级联途径、H₂O₂参与了盐、干旱胁迫下活性氧产生、抗氧化酶活性变化和RbohC、RbohF基因表达的调控.     

Evidence for inhibitory substrate interactions during cometabolism of 3,4-dichlorobenzoate by Acinetobacter sp. strain 4-CB1

Abstract Acinetobacter sp. strain 4-CB1 cometabolized 3,4-dichlorobenzoate (3,4-DCB), via 3-chloro-4-hydroxybenzoate (3-C-4-OHB) and 4-carboxy-1,2-benzoquinone, in the presence of 4-chlorobenzoate (4-CB) as a growth substrate. In resting cell incubations, 3,4-DCB acted competitively as an inhibitor with 4-CB metabolism, and as a substrate inhibitor of its own metabolism. The inhibitor constant K _i and the affinity constant K _m were 800 and 181 μM, respectively with a maximal rate of 3,4-DCB disappearance of 18.8 nmol 3,4-DCB min⁻¹ (mg protein)⁻¹, in resting cells incubated solely with 3,4-DCB. Resting cells were less tolerant to 3,4-DCB than growing cells, as noted from the inhibition constants ( K _i). Moreover, 3-C-4-OHB competitively inhibited 4-hydroxybenzoate monooxygenase by acting as a pseudosubstrate ( K _i= 7.3 μ M). The next sequential intermediate, 4-carboxy-1,2-benzoquinone, uncompetitively inhibited 4-CB metabolism in resting cell incubations. Thus, 3,4-DCB inhibited its own cometabolism as well as metabolism of 4-CB in Acinetobacter sp. strain 4-CB1.     

辽宁省三级保护植物木根黄芩考证及其与京黄芩比较形态学研究

木根黄芩(Scutellaria planipes Nakai et Kitag.)是唇形科黄芩属(Scutellaria L.)多年生草本,目前仅发现在辽宁省凌源市境内有零星分布,被辽宁省列为三级保护植物。该种发表于1934年,但《中国植物志》、Flora of China、《中国生物物种名录》均将其定为京黄芩(Scutellaria pekinensis Maxim.)的异名。为了阐明二者的差异性,本文首先对木根黄芩的原始文献、模式标本、模式产地、历史分布区及现今发现地进行考证,其次对二者进行差异比较研究,认为木根黄芩与京黄芩无论在分布范围和生境上,还是在宏观外部形态和微观花粉粒形态上均存在明显差异,确定木根黄芩为独立种,同时还对木根黄芩的果实进行形态补充描述。本文确定木根黄芩独立种的地位,对保护野生木根黄芩具有重要意义,同时对其药用价值的进一步研究提供了更为清晰的样本。     

Mechanism of hydroxyl radical scavenging by rebamipide: identification of mono-hydroxylated rebamipide as a major reaction product

Rebamipide, an antiulcer agent, is known as a potent hydroxyl radical (_•OH) scavenger. In the present study, we further characterized the scavenging effect of rebamipide against _•OH generated by ultraviolet (UV) irradiation of hydrogen peroxide (H₂O₂), and identified the reaction products to elucidate the mechanism of the reaction. Scavenging effect of rebamipide was accessed by ESR using DMPO as a _•OH-trapping agent after UVB exposure (305 nm) to H₂O₂ for 1 min in the presence of rebamipide. The signal intensity of _•OH adduct of DMPO (DMPO-OH) was markedly reduced by rebamipide in a concentration-dependent fashion as well as by dimethyl sulfoxide and glutathione as reference radical scavengers. Their second order rate constant values were 5.62 × 10₁₀, 8.16 × 10₉ and 1.65 × 10₁₀ M_-1 s_-1, respectively. As the rebamipide absorption spectrum disappeared during the reaction, a new spectrum grew due to generation of rather specific reaction product. The reaction product was characterized by LC-MS/MS and NMR measurements. Finally, a hydroxylated rebamipide at the 3-position of the 2(1H)-quinolinone nucleus was newly identified as the major product exclusively formed in the reaction between rebamipide and the _•OH generated by UVB/H₂O₂. Specific formation of this product explained the molecular characteristics of rebamipide as a potential _•OH scavenger.     

Expression of a biologically active analogue of somatomedin-C/insulin-like growth factor I

A synthetic gene coding for an analogue of somatomedin-C/insulin-like growth factor I (Sm-C/IGF-I) was synthesized by solid support phosphoramidite chemistry and subsequently cloned and expressed in Escherichia coli as a fusion protein. The gene, designed with a threonine codon substituted for a methionine codon at position 59 was expressed fused to an eight-amino acid leader peptide under the direction of the E. coli tryptophan promoter. The fusion protein, termed L0-[Thr59]-Sm-C/IGF-I was purified extensively (greater than 97%) and found to be 60% as active as native Sm-C/IGF-I in a radioimmunoassay and 50% as potent as native Sm-C/IGF-I in a radioreceptor assay. Like native Sm-C/IGF-I it was also mitogenic for Balb/c 3T3 cells. After removal of the eight amino acid leader peptide by cyanogen bromide treatment, the resulting threonine analogue, termed [Thr59]-Sm-C/IGF-I was 80% as potent as native Sm-C/IGF-I in both the RIA and the radioreceptor assays. It was also mitogenic in Balb/c 3T3 cells. These two analogues, therefore, display biological activities similar to human-derived Sm-C/IGF-I.     

Binding inhibition of various influenza viruses by sialyllactose-modified trimer DNAs

Sialyllactose (SL)-modified trimer DNAs with a similar SL presentation as their binding sites on influenza virus hemagglutinin (HA) trimer were designed and synthesized. These trimer DNAs showed high affinity for various influenza viruses, including A/Puerto Rico/08/34 (H1N1), A/Beijing/262/95 (H1N1), A/Yokohama/77/2008 (H1N1), and A/Panama/2007/99 (H3N2). Thus, presentation of SL residues on three vertexes of the scaffold as well as sialic acid binding sites on the HA trimer regardless of a tri-branched or triangular scaffold are important for high affinity for influenza viruses. These compounds have the potential for use in detection and as inhibitors of a broad spectrum of influenza viruses.     

The nitrite oxidizing system of Nitrobacter winogradskyi

Abstract Cytochrome components which participate in the oxidation of nitrite in Nitrobacter winogradskyi have been highly purified and their properties studied in detail. Cytochrome a ₁ c ₁ is an iron-sulphur molybdoenzyme which has haems a and c and acts as a nitrite-cytochrome c oxidoreductase. Cytochrome c -550 is homologous to eukaryotic cytochrome c and acts as the electron mediator between cytochrome a ₁ c ₁ and aa ₃-type cytochrome c oxidase. The oxidase is composed of two kinds of subunits, has two molecules of haem a and two atoms of copper in the molecule, and oxidizes actively eukaryotic ferrocytochrome c as well as its own ferrocytochrome c -550. Further, a flavoenzyme has been obtained which has transhydrogenase activity and catalyses reduction of NADP⁺ with benzylviologen radical. This enzyme may be responsible for production of NADPH in N. winogradskyi . The electron transfer against redox potential from NO₂⁻ to cythochrome c could be pushed through prompt removal by cytochrome aa ₃ of H⁺ formed by the dehydrogenation of NO₂⁻+ H₂O. As cytochrome c in anaerobically kept cell-free extracts is rapidly reduced on addition of NO₂⁻, a membrane potential does not seem necessary for the reduction of cytochrome c by cytochrome a ₁ c ₁ with NO₂⁻ in vivo.     

Growth-promoting activity of gibberellins on shoot elongation in Salix pentandra is reduced by 16,17-dihydro derivatisation

The metabolism of GA₁₀ is thought to be under photoperiodic control in the woody plant Salix pentandra . However, in a recent study using 16,17-[³H₂]GA₁₉ as a mimic of Ga₁₀, no effect of photoperiod was found on its metabolism to 16,17-dihydro-GA₂₀ and 16,17-dihydro-GA₁. To investigate if this was due to differential action of exogenous 16,17-dihydro-GAs and GAs, the effects of the 16,17-dihydro-derivatives of the gibberellins GA₁₉, GA₁, and GA₁ as compared with their parent GAs, on shoot elongation in seedlings of S. pentandra were studied. 16,17-Dihydro-GA₁₉, and -GA₂₀ were both almost inactive, while 16,17-dihydro-GA₁ induced some shoot elongation in seedlings treated with ancymidol as well as under short days. GA₁₉, GA₂₀ and GA₁ were all able to counteract the inhibitory effect of ancymidol under continuous light, while inhibition induced by a 12-h photoperiod was antagonised only by GA₂₀ and GA₁. Thus, the growth-stimulating activity of the tested GAs is significantly reduced by 16,17-dihydro derivatisation, but the derivatives do not inhibit stem elongation in S, pentandra , as has been found in monocotyledons.