Acidic extracellular pH promotes activation of integrin α(v)β(3)

Acidic extracellular pH is characteristic of the cell microenvironment in several important physiological and pathological contexts. Although it is well established that acidic extracellular pH can have profound effects on processes such as cell adhesion and migration, the underlying molecular mechanisms are largely unknown. Integrin receptors physically connect cells to the extracellular matrix, and are thus likely to modulate cell responses to extracellular conditions. Here, we examine the role of acidic extracellular pH in regulating activation of integrin α(v)β(3). Through computational molecular dynamics simulations, we find that acidic extracellular pH promotes opening of the α(v)β(3) headpiece, indicating that acidic pH can thereby facilitate integrin activation. This prediction is consistent with our flow cytometry and atomic force microscope-mediated force spectroscopy assays of integrin α(v)β(3) on live cells, which both demonstrate that acidic pH promotes activation at the intact cell surface. Finally, quantification of cell morphology and migration measurements shows that acidic extracellular pH affects cell behavior in a manner that is consistent with increased integrin activation. Taken together, these computational and experimental results suggest a new and complementary mechanism of integrin activation regulation, with associated implications for cell adhesion and migration in regions of altered pH that are relevant to wound healing and cancer.     

如何准确高效检定实验室pH(酸度)计

在检定实验室pH(酸度)计中严格按照检定规程进行检定工作,结合酸度计检定仪的使用说明书及被检的各种型号规格的酸度计使用说明书进行实际操作,基于可操作性,针对规程及检定仪的使用方面应注意的问题以及检测流程给以详细论述,以达到准确高效的检定实验室pH(酸度)计。     

耐高温消毒pH电极和DO(溶解氧)电极

耐高温消毒GKFpH电极和DO(溶解氧 )电极是我所科技项目成果产品 ,pH电极曾获得“七五”攻关重大科技成果奖、中国科学院科技进步二等奖 ,广泛应用于制药、生化制品、味精、食品发酵、石油、血制品、化工等行业的在线检测 ,能适时掌握生产过程中pH、DO参数的变化 ,是提高产品质量、产量的重要手段。pH电极和二次仪表经上海技术监督局和化工部化工专用仪器仪表质量监督检验中心随机检测 ,结果表明 ,该产品性能指标和产品质量优良。通过几代申东人的奋斗 ,目前产品质量更尽善尽美。主要技术指标 :1 .pH电极　测量范围 :pH1～ 1 2灭菌温度…     

耐高温消毒pH电极和DO(溶解氧)电极

耐高温消毒ＧＫＦｐＨ电极和ＤＯ(溶解氧)电极是我所科技项目成果产品,ｐＨ电极曾获得“七五”攻关重大科技成果奖、中国科学院科技进步二等奖,广泛应用于制药、生化制品、味精、食品发酵、石油、血制品、化工等行业的在线检测,能适时掌握生产过程中ｐＨ、ＤＯ参数的变化,是提高产品质量、产量的重要手段。ｐＨ电极和二次仪表经上海技术监督局和化工部化工专用仪器仪表质量监督检验中心随机检测,结果表明,该产品性能指标....     

Valbro : un nouveau site à vertébrés de l’Oligocène inférieur (MP 22) de France (Quercy). II – Oiseaux (Aves)

The bird remains from Valbro belong only to three taxa, Paraortyx lorteti, Archaeotrogon venustus, and A. zitteli. This association makes it possible to ascribe to this locality an early Oligocene age, reference-levels MP 22 or MP 23, which is in agreement with the age given by the mammals.     

Low pH (6, 5 and 4) sulfate reduction during the acidification of sucrose under thermophilic (55 °C) conditions

The effect of a low pH (6, 5 and 4) and different COD/SO₄²⁻ ratios (9 and 3.5) on thermophilic (55 °C) sulfate reduction and acidification of sucrose was investigated using three upflow anaerobic sludge bed reactors fed with sucrose at an organic loading rate of 3.5 gCOD (l_reactor d)⁻¹. The three reactors showed nearly 100% acidification of sucrose for all pH values and COD/SO₄²⁻ ratios investigated. Sulfate reduction was complete at pH 6 and a COD/SO₄²⁻ ratio of 9. At pH 5, sulfate reduction efficiencies were 80–95% for both COD/SO₄²⁻ ratios (9 and 3.5). At pH 4, sulfate reduction efficiencies further dropped to 55–65% at a COD/SO₄²⁻ ratio of 9 and 30–40% at a COD/SO₄²⁻ ratio of 3.5. The pH decrease from 6 to 5 or 4 caused a shift in the acidification products from mainly acetate to butyrate, as well as a higher production of ethanol, especially at pH 4. At pH 4, propionate and methane were not formed and hydrogen concentrations in the biogas reached 50%, equivalent to a hydrogen yield of 1.3 mol H₂ (mol glucose)⁻¹. This study shows that sulfate reduction is possible in the acidification phase of anaerobic wastewater treatment at pH values as low as 6 till 4 and that the pH strongly affects both the acidification pathways and the sulfate reduction efficiencies.     

Sinularia leptoclados (Ehrenberg, 1834) (Cnidaria,?Octocorallia) re-examined

Sinularia leptoclados (Ehrenberg, 1834) is re-described. Sinularia leptoclados var. gonatodes Kolonko, 1926 is synonymized with Sinularia maxima Verseveldt, 1977. Two new species of Sinularia with digitiform lobules, leptoclados-type surface clubs and unbranched interior spindles, are described. An updated maximum likelihood tree of Sinularia species with leptoclados-type clubs (clade 5C) based on two mitochondrial genes (mtMutS, COI) and a nuclear gene (28S rDNA) is presented.     

作者索引(1990;Volume 6)

Ba ZhengfengB ian RulianCai PingCai YingnianCao YinxiangChell GengxinChen rlaozh:-Chenl一JuaiqingChen JiqiangChen JiqiuChen Ji、lzer,gChen JialiangChen JiaPei巴正丰卞如赚蔡平蔡英年曹银祥陈庚新陈颧珠陈槐卿陈季强陈吉球陈继生陈佳亮陈家佩Chen JieCI,en JunhuiChen LianbiChcn MingzlzeChen PeixiChen PinfangCI又en RendunChen ShiliangChen ShuzhiChen WanyingChen XiushengChe若1 YingmaoChen YizhangChel飞y、zhuaiChen ZhcnxingChen ZhengyuChen Zht!huaCheng HaiyunCheng JiataiChi Kuixia…     

作者索引(1993;Volume 9)

Ai Hongbing艾洪滨Ai Mingxian艾明仙An Gang安刚Bai Zhiquan柏志全Bao Yunhua鲍云华Bi Yutian毕玉田Cai Yan蔡淡Cai Yingnian蔡英年Cai Yingyun蔡映云Cao Hong列曹宏宇Cao Yinxiang一曹银祥Cao zhaofeng曹兆丰Cao zhenwu曹祯吾Chang Zhijie常志杰cho Gang陈刚Chen Jisheng陈继生Chen Jiajin陈家津Chen JiaPei陈家佩Chen Jianguo陈建国Chen Jiankang陈健康Chen Jie陈杰Chen Junpao陈俊抛Chen Limin陈丽敏Chen Long陈龙Chen Peixi陈培熹Chen Rendun陈仁博Chen Rongsan陈荣三Chen Shen郎i陈生弟Chen Xiaoling陈晓玲Che…     

Hydrogen peroxide (H<Subscript>2</Subscript>O<Subscript>2</Subscript>) and methyl-β-cyclodextrin (MβCD) down regulate caveolin expression in human lens epithelial cells (HLECs)

Oxidative stimulation induced by hydrogen peroxide (H₂O₂) on human lens epithelial cells (HLECs) was performed to observe the effects on cell viability and caveolin expression, and cholesterol depletion in HLECs caused by methyl-β-cyclodextrin (MβCD) was also studied. SRA01/04 HLECs were exposed to H₂O₂ or MβDC of various concentrations and durations. We used a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to measure the effect of H₂O₂ on the viability of SRA01/04 HLECs. The distributions of caveolins after oxidative stimulation were probed by fluorescence microscopy and laser scanning confocal microscopy. Immunoblotting was performed to analyze alterations of caveolins expression. We observed that the viability of SRA01/04 HLECs under 0.1 mM H₂O₂ for 10 min or longer was significantly reduced (*p < 0.05, F = 11.63). Laser scanning microscopy showed immunofluorescent caveolins in SRA01/04 HLECs under 0.1 mM H₂O₂ for 10 min or longer; caveolins were largely confined to intracellular domains. Western blots showing both membrane and total caveolin protein (22 kDa) levels in SRA01/04 HLECs treated with 0.1, 0.2, 0.5, or 1.0 mM H₂O₂ for 30 min were significantly reduced, compared with the untreated (*p < 0.05, F = 6.149, or *p < 0.05, F = 14.489, respectively). In addition, the membrane and total caveolin protein level after being treated with 0.1 mM H₂O₂ (*p < 0.05, F = 6.843, or *p < 0.05, F = 7.944, respectively) for different durations also down regulated. Fluorescence microscopy also showed that phosphorylated caveolin-1 was distributed near the focal adhesions of the cells. This study concludes that the responses of HLECs to oxidative stress may include down regulation of caveolin and phosphorylation of caveolin-1 on tyrosine 14 and that MβCD also down regulates caveolin while depleting cholesterol in HLECs. Published in Russian in Molekulyarnaya Biologiya, 2007, Vol. 41, No. 6, pp. 994–1001. The article was submitted by the authors in English.     

黑曲霉(Aspergillus niger)发酵生产木聚糖酶的pH调控策略

为了提高黑曲霉(Aspergillus niger)D08生产木聚糖酶的能力,考察了不同p H条件对菌株生长及产酶的影响,结果发现木聚糖酶发酵过程中菌体生长的最适p H与木聚糖酶合成的最适p H不同,分别为3.5和4.5。由此针对性地提出了两阶段p H控制策略:在30 h内控制p H为3.5;30 h后p H控制为4.5。结果表明:分阶段p H调控策略的实施进一步提高了菌体合成木聚糖酶的能力,木聚糖酶比酶活(2 223.38 U/m L)和生产强度(26.47U/(m L·h))分别比恒定p H 4.5时提高了14.3%和30.6%。该工艺对提高木聚糖酶活力具有一定的指导意义,为后续研究和生产奠定了良好的基础。     

遗传性平衡易位t(3; 22) (p21; q13）家系

本文报道一例t(3; 22) (p21; q13）平衡 相互易位的家系。先证者，男性，一岁半，淋巴 细胞及皮肤成纤维细胞G带分析结果：核型均 为46, XY, t(3; 22)(p21；q13）或46, XY,t(3; 22)(3gter” 3p21：：22813” 22gter；2 2 pter” 22gl3::3p21” 3 pter )；先证者母亲（图1）与 外祖母核型均为46, XX, t(3; 22)(p21; q13) 或46, XX, t(3; 22)(3gter、3p21：:22813一 22gter; 22pter～ 22813：:3p21一3pter)。经银 染与G带复合显示技术，先证者及母亲的22der 可见清晰的AgNOR区。先证者的父亲与舅父 G带分析核型正常。在此情况下，有生育正常 婴儿的可能，但必须作产前诊断。     

Dynamics of planktonic food webs in three mining lakes across a pH gradient (pH 2–4)

Acidic mining lakes (ML) in Lusatia (Germany) are characterised by their geogenically determined chemistry. The present study describes the structure, main components and relationships within the food webs of three acidic mining lakes with different pH values (ML 111: pH 2.6; ML 117: pH 2.8; ML Felix: pH 3.6) in order to show their typical characteristics. The investigation covered the period 1995–1997. The number of species and the biomass are both low, but increase with increasing pH. Planktonic components in the most acidic ML 111 (pH 2.6–2.9) comprise bacteria, Ochromonas spp. and Chlamydomonas spp. and a few rotifers (E. worallii, C. hoodi). Heliozoans are the top-predators. In ML 117 (pH 2.8–3) Gymnodinium sp., ciliates, the rotifer B. sericus and the pioneer crustacean Chydorus sphaericus join the pelagial community. Heliozoans were not found in ML 117 or ML Felix (pH 3.4–3.8). ML Felix had the most taxa. The benthic food chain of all three lakes includes phytobenthic algae as producers, chironomids as primary consumers and corixids as top predators in the profundal. Corixids predate on small cladocerans inhabiting the pelagial in lakes with a pH above 2.8 such as ML Felix. They invade the pelagial and act as a connecting link between the benthic and the pelagic food chains, which are isolated in lakes with a lower pH. Occasionally primary producers and consumers were abundant in all three lakes. These organisms do not depend on the degree of acidity, but on the availability of essential ressources. Mass variations covered up any seasonal variation in the extremely acidic ML 111 (0.9 mm³ l^–1), while in the other two lakes seasonal patterns of biomass were found.     

Evidence for ΔpH surface component (ΔpH) of proton motive force in ATP synthesis of mitochondria

Background

One of the central debates in membrane bioenergetics is whether proton-dependent energy coupling mechanisms are mediated exclusively by protonic transmembrane electrochemical potentials, as delocalized pmf, ΔµH⁺, or by more localized membrane surface proton pathways, as interfacial pmf, ΔµH^S.

Methods

We measure ?pH^S in rat liver mitoplasts energized by respiration or ATP hydrolysis by inserting pH sensitive fluorescein-phosphatidyl-ethanolamine(F-PE) into mitoplast surface.

Results

In the presence of rotenone and Ap5A, succinate oxidation induces a bi-phasic interfacial protonation on the mitoplast membranes, a fast phase followed by a slow one, and an interfacial pH decrease of 0.5 to 0.9 pH units of mitoplast with no simultaneous pH changes in the bulk. Antimycin A, other inhibitors or uncouplers of mitochondrial respiration prevent the decrease of mitoplast ?pH^S, supporting that ΔµH^S is dependent and controlled by energization of mitoplast membranes. A quantitative assay of ATP synthesis coupled with ?pH^S of mitoplasts oxidizing succinate with malonate titration shows a parallel correlation between ATP synthesis, State 4 respiration and ?pH^S, but not with ?Ψ_E.

General Significance

Our data substantiate ?pH^S as the primary energy source of pmf for mitochondrial ATP synthesis. Evidence and discussion concerning the relative importance and interplay of ?pH^S and ?Ψ_E in mitochondrial bioenergetics are also presented.     

Carbon dioxide capture by planar (AlN)<Subscript>n</Subscript> clusters (<Emphasis Type="Italic">n</Emphasis>=3–5)

Searching for materials and technologies of efficient CO₂ capture is of the utmost importance to reduce the CO₂ impact on the environment. Therefore, the (AlN)_n clusters (n = 3–5) are researched using density functional theoretical calculations. The results of the optimization show that the most stable structures of (AlN)_n clusters all display planar configurations at B3LYP and G3B3 methods, which are consistent with the reported results. For these planar clusters, we further systematically studied their interactions with carbon dioxide molecules to understand their adsorption behavior at the B3LYP/6–311+G(d,p) level, including geometric optimization, binding energy, bond index, and electrostatic. We found that the planar structures of (AlN)_n (n = 3–5) can capture 3–5 CO₂ molecules. The result indicates that (AlN)_n (n = 3–5) clusters binding with CO₂ is an exothermic process (the capture of every CO₂ molecule on (AlN)_n clusters releases at least 30 kcal mol^-1 in relative free energy values). These analysis results are expected to further motivate the applications of clusters to be efficient CO₂ capture materials.     

一例罕见的t(6;18) del(18)综合征

Gouw等于1973年首次报道了t(6;18)(p22;q12)病例。同年,Nakagme等也发现了t(6;18)(q27;q11)核型。迄今国外共发现至少9种关于t(6;18)核型。而国内尚未见公开报道。 作者从遗传咨询门诊病人中,检出一例至今未见报道过的t(6;18)del(18)综合征患者。现简要报告如下。     

pH值对高效液相(OPA法)测定氨基酸的影响

<正> 前言氨基酸的分离是在强阳离子中变换柱子通过pH梯度进行的。洗脱出来的各种氨基酸再与OPA反应生成衍生物,最后应用萤光检测分离出的各种氨基酸。其反应如下: