耦合生物细胞体系中内噪声对检测弱刺激的积极作用

By constructing a mesoscopic stochastic model for intracellular calcium oscillations in coupled cell system, we investigated the influence of internal noise on the detection of weak stimulation using the chemical Langevin equation (CLE). We found that an optimal cell size V existed for a coupled cell chain length N and an optimal value of N existed for a given cell size V. At these values, the collective calcium oscillations showed the best performance, indicating the occurrence of“system size resonance (SSR)”or“internal noise stochastic resonance (INSR)”. And such a phenomenon was robust to the coupling strength. Living cells may have learned to exploit the internal noise to detect weak stimulation via the mechanism of INSR, and then encode information to specifically regulate distinct cellular functions. It is interesting to note that the optimal cell size is always present at V抑103 μm3, which is close to the real living cell size in vivo. Since the internal noise in living systems can not be ignored and the systems may often encounter weak stimulations, our findings might have significance for stimulation detecting processes in living systems.     

细胞内钙离子体系中的双参数内信号随机共振

自从Benzi等于1981年提出随机共振(SR)现象以来,它已经受到物理、化学和生物学等领域的关注．SR是非线性体系中弱外信号和环境扰动之间的协同作用．后来胡岗等发现外信号可以由体系的内信号所代替,此时出现的SR被称为内随机共振(ISR)．通常对SR的研究都集中在外信号和噪音扰动参数上,如电压、电流和压力等．     

阳极溶解电化学振荡体系中白噪声诱导随机共振的模拟

通过对电化学阳极溶解振荡模型加白噪声后引发的随机共振现象的模拟研究发现,在该体系的周期二振荡态时呈现显性内信号随机共振现象。当白噪声加在该电化学体系的周期二振荡态时,内信号的信噪比随着噪声的增大达到了最大值。同样噪声强度情况下,强信号的信噪比增加比弱信号的增加更加迅速。如果同时改变噪声强度,体系的信号频率也维持不变。研究表明,噪声对内信号的优化具有选择性,而体系的内信号也具有抵抗噪声和维持内在机制不变的性质。     

钙离子体系中隐式和显式内随机共振

近年来, 细胞内钙离子信号及其产生机理已成为研究热点之一, 这是因为钙离子信号能控制细胞的生死、 传递细胞间的信息、 提高基因表达的有效性和特殊性[^1~3]. 在钙离子信号传递过程中, 受环境扰动是不可避免的. Shuai等^[4]发现噪音能够控制钙离子通道中钙离子的释放. 在过去的十年中, 无论是物理、 化学还是生物体系^[5~10]的噪音效应已被广泛研究, 其中包括对随机共振(SR)的研究^[5], 经典SR是环境噪音能够放大弱的外加信号. 但随着研究的深入, 发现有无噪音SR^[11]和内SR(ISR) ^[6]. ISR的内信号来自噪音诱导的内信号, 这种SR现象叫隐式内SR(IISR). 而我们则发现了另外一种内SR, 即显式内SR(EISR) ^[12], 它的内信号是体系固有的内信号, 而不是由噪音诱导的. 本文主要研究加入外信号将对IISR和EISR产生的影响.     

介观振荡化学反应体系的内噪声随机共振

用化学Langevin方程研究了内噪声对介观振荡化学反应体系的影响.研究发现,在确定性体系处于定态条件下,内噪声可以导致体系振荡:随着内噪声强度的变化,诱导振荡信号的信噪比通过一个极大值,表明内噪声随机共振的出现;由于内噪声强度随着系统体积的变化而改变,因此,这一现象也证明了系统尺度共振,即最佳尺度效应的存在.     

Constructive Role of Internal Noise for the Detection of Weak Signal in Cell System

Taking into account the existence of internal noise in small scale biochemical reaction systems, we studied how the internal noise would influence the detection of weak external signal in the cell system using chemical Langevin equation. The weak signal was too small to, separately, fire calcium spikes for the cell. We found that, near the Hopf bifurcation point, the internal noise could help the calcium oscillation signal cross a threshold value, and at an optimal internal noise level, a resonance occurred among the internal noise, the internal noise-induced calcium oscillations, and the weak signal, so as to enhance intensively the ability of the cell system to detect the weak signal. Since the internal noise was changed via the cell size, this phenomenon demonstrated the existence of an optimal cell size for the signal detection. Interestingly, it was found that the optimal size matched well with the real cell size, which was robust to external stimulus, this was of significant biological meaning.     

细胞体系中内噪声对弱信号检测的积极作用

在小尺度的生物化学反应体系中内噪声是普遍存在的,本文采用化学Langevin方程研究了细胞体系中内噪声对弱信号检测的作用. 研究发现, 在Hopf分岔点附近, 当弱信号非常小以至于不能独立地激发细胞内的钙尖峰振荡时, 内噪声能够帮助细胞内的钙振荡信号越过一个域值, 并且在一个最佳的内噪声强度下, 内噪声、内噪声诱导的钙振荡和弱信号之间会产生共振现象, 由此极大地增强了细胞体系对弱信号的检测能力. 由于内噪声是通过细胞尺度变化而改变的, 因此这种现象也说明了在对弱信号检测行为中最佳细胞尺度的存在. 研究还发现最佳的细胞尺度与真正的细胞体积是相吻合的, 并且基本不随外界刺激的改变而改变, 这具有重要的生物学意义.     

自催化三分子模型内噪声随机共振

The stochastic resonance in chemical reaction systems has recently attracted growing attentions. Using chemical Langevin equation,the effect of internal noise has been studied on the dynamical behavior of a single and a one-way coupled cubic autocatalator. For the single system,it is found that the internal noise can induce sustained oscillations,and the signal-to-noise ratio（SNR）undergoes a maximum with the variation of the system size. For the coupled system,the SNR passes through a maximum with changing coupling strengths as well as with changing system sizes,which demonstrates the occurrence of the internal noise stochastic resonance（INSR）and optimal size effect. In the presence or absence of influx into the system,the coupling enhanced or suppressed INSR is found in the coupled system. All cells of the coupled system appear to exhibit INSR at an approximately equal size at a suitable coupling strength,implying that the optimal system size and coupling strength can make the system reach an optimal chemical reaction state.     

钙离子体系的振动双共振控制

研究了钙离子振荡体系在高、低两种不同频率信号作用下所产生的振动双共振(VBR)及其控制方法.结果表明:系统对低频信号响应的幅值随高频信号振幅的变化产生了振动双共振现象,并且低频信号的频率越低,振幅越大,系统通过振动双共振对微弱低频信号的放大倍数越大.体系离霍普夫(Hopf)分岔点的距离越近(控制参数域值越小),体系发生振动双共振所需要的最大高频信号幅值越往大的方向漂移,同时体系振动双共振的强度越小.细胞内钙波形成过程中的反馈机制对体系振动双共振的增强和减弱起着重要的作用,即正反馈机制对体系振动双共振强度起增强的作用,而负反馈机制却起减弱的作用.另外,体系中引入噪音所产生的随机共振不仅削弱振动双共振的强度而且还影响振动峰的个数,也发现存在极限噪音强度使体系产生不同的振荡行为,极限噪音强度之下,体系产生VBR现象,而极限噪音强度之上,体系则发生单峰振荡共振现象.     

色噪声性质对一氧化氮还原反应体系随机共振的影响

研究了一定温度条件下和NO气体偏压pNO处在超临界Hopf分岔点附近时,Pt(100)/NO+CO表面催化还原反应体系被色噪声调制后的动力学行为.通过计算机模拟,观察到了色噪声诱导的反应振荡和随机共振现象.探讨了色噪声强度和相关时间对随机共振行为的影响,得到一些新的结果.     

溶剂尺寸对ABA两亲性三嵌段共聚物在选择性溶剂中自组装行为影响的Monte Carlo模拟

采用Monte Carlo模拟方法研究了溶剂尺寸对ABA两亲性三嵌段共聚物在选择性溶剂中自组装行为的影响。模拟结果表明,溶剂尺寸是决定共聚物聚集形态的重要因素之一。随着溶剂尺寸的增大,嵌段共聚物自组装所形成的胶束可以发生从球状到棒状再到囊泡状的转变。通过对各组分的相互作用对数随溶剂尺寸变化曲线的分析发现,增大溶剂尺寸会使溶剂的溶解性变差,由此引发体系中的一系列形态转变。此外,通过对体系自组装形貌结构相图的分析发现,增大溶剂尺寸或增加疏水作用同减小亲水作用对于自组装形态的改变具有同等效果。     

Determination of End-to-End Distances in a Series of TEMPO Diradicals of up to 2.8 nm Length with a New Four-Pulse Double Electron Electron Resonance Experiment

A four-pulse version of the pulsed double electron electron resonance (DEER) experiment has been applied to a series of TEMPO diradicals with well-defined interradical distances ranging from 1.4 to 2.8 nm (see picture). The new pulse sequence allows broad distributions of electron–electron distances to be measured without dead-time artifacts.     

溴酚蓝共振光散射探针测定敦煌壁画胶结材料中蛋白质含量

溴酚蓝共振光散射探针测定敦煌壁画胶结材料中蛋白质含量;敦煌壁画; 颜料胶结剂; 共振光散射; 蛋白质; 溴酚蓝     

Analytical Strategy for the Determination of Selenium in Biological Materials by Inductively Coupled Plasma-Mass Spectrometry with a Dynamic Reaction Cell

Selenium was determined in serum, hair, and tobacco by inductively coupled plasma-mass spectrometry using ⁷⁷Se, ⁷⁸Se, and ⁸²Se. The set of standards method (SSM) and the standard addition method (SAM) were applied to calibration with and without the use of internal standards (⁷²Ge and ¹⁰³Rh). In addition, the usefulness of the dynamic reaction cell (DRC) with methane as the reaction gas was characterized. The results obtained in different conditions were evaluated in terms of precision and accuracy. It was demonstrated theoretically and experimentally that an internal standard is a potential source of systematic errors as it can be influenced multiplicatively and additively by its own interferents (independently of selenium). Furthermore, it was shown that—against common opinion—an internal standard can fail in elimination of chemical interference effects influencing selenium and in increasing of precision of selenium determinations. The DRC was shown to be effective in the elimination of additive effects, although the results obtained by both SSM and SAM with DRC were systematically positively erroneous. Finally, selenium was determined accurately in each examined sample when SAM was applied to calibration, and signals were measured either for ⁸²Se without the use of the DRC, or for ⁷⁷Se or ⁷⁸Se with the use of the DRC. In addition, it has also been shown that samples should be diluted prior to analysis to the greatest acceptable extent.     

钴(II)-2-(5-溴-2-吡啶偶氮)-5-二乙氨基酚体系共振瑞利散射法测定环境 水样中十二烷基苯磺酸钠

在pH 1.8～3.0的Britton-Robinson (BR)缓冲溶液中, 钴(II)与2-(5-溴-2-吡啶偶氮)-5-二乙氨基酚(5-Br-PADAP)(HL)反应形成紫红色螯合阳离子, 此时仅能引起吸收光谱的变化, 不能导致共振瑞利散射(RRS)的增强. 当钴(II)-5-Br-PADAP螯合阳离子与阴离子表面活性剂十二烷基苯磺酸钠(SDBS)、十二烷基磺酸钠(SLS)和十二烷基硫酸钠(SDS)作用时, 仅能与SDBS进一步反应形成三元离子缔合物并引起RRS的显著增强, 而不与SDS和SLS产生类似反应. 离子缔合物的RRS峰分别位于306, 370和650 nm处, 在一定范围内RRS增强(ΔI)与SDBS浓度成正比, 当用650 nm处测量时, 其检出限为0.043 μg•mL－1, 线性范围为0.14～6.0 μg•mL－1. 文中研究了反应产物的RRS光谱特征, 适宜的反应条件及分析化学性质, 据此发展了一种在一定量SDS和SLS等阴离子表面活性剂存在下选择性测定SDBS的新方法, 方法灵敏、简便、快速,用于天然水和污水中SDBS的测定, 获得满意结果. 文中还对反应机理进行了讨论.     

A Jet Ring Cell with a Renewable Solid Support for Amperometric Detection of Glucose in a Sequential Injection Analysis System

Abstract

A new amperometric method for the detection of glucose has been developed. A jet ring cell with a renewable solid support (JRR) is connected to a sequential injection analysis (SIA) system. The solid support, consisting of small spherical particles of agarose gel, with a mean bead size of 90 μm, is coupled with the enzyme glucose oxidase (GOD). The suspension is injected through a multiport valve in the SIA-system and is trapped in the JRR cell by a gap of 10 μm between the glassy carbon (GC) working electrode and a stainless steel counter electrode. The subsequent injection of glucose results in formation of hydrogen peroxide, which is detected by oxidation at 1.0 V (vs. Ag/AgCl/KCl (3 M)). Thereafter the suspension is removed by reversing the pump flow and subsequently replaced with fresh suspension for the next determination of glucose. The linear working range for the JRR-sensor, at this stage of the work, is 100 μM - 5 mM.     

芯片式流通池用于顺序注射可更新表面荧光免疫法测定人血清中的IgG

采用芯片式流通池作为非均相免疫反应和原位固相荧光检测的场所,用双岔光纤将芯片式流通池与荧光光度计耦联,以双抗夹心式非均相免疫反应的模式,研究建立了测定人血清中IgG的顺序注射可更新表面非均相免疫分析新方法.     

顺序注射可更新表面固相荧光免疫法测定人血清中免疫球蛋白G

建立了采用芯片式微型流通池的测定人血清中免疫球蛋白G(IgG)的顺序注射可更新表面非均相荧光免疫分析法。将羊抗人IgG抗体固定于包被有蛋白A的Sephamse CL4B凝胶微珠,然后制备成固相抗体。用标记FITC的抗人IgG抗体作为第二抗体。固相抗体、血清试样和荧光标记第二抗体由顺序注射系统注入芯片式微型流通池,并在其中进行免疫反应生成夹心式抗体．抗原荧光复合物。荧光分光光度计通过光纤与流通池耦合测定截留于流通池中的抗体一抗原复合物荧光强度。一次测定完成后,微珠即被排出流通池。流通池经缓冲液清洗后即可进行下一次测定。体系经优化后,检出限为0．1mg／L IgG,分析速率达到11次／h。3．9mg／L IgG的日内和日间精密度(RSD)分别为1．7％和5．2％;校正曲线的线性范围为0．3—7．0mg／L IgG。所建立的方法已成功地应用于人血清中IgG的测定。     

附子配伍过程中二萜类生物碱在Caco-2小肠吸收细胞模型中吸收转运的UPLC/MS研究

利用Caco-2细胞单层模型和超高效液相色谱-三重四极杆电喷雾质谱联用方法, 考察附子中乌头类生物碱提取物的跨膜转运. 在相同浓度的附子乌头类生物碱溶液中, 加入干姜、甘草、半夏及浙贝母的水提物(折合药材质量比例为1∶1), 系统考察了加入前后的表观渗透系数(P_app). 结果表明, 加入配伍药材后附子中11种二萜类生物碱的P_app发生了明显的变化. 干姜、甘草和半夏水提物的加入能够明显地降低二萜类生物碱在小肠中的生物利用度, 尤其抑制其中毒性较大的双酯型生物碱的生物利用度|而浙贝母的水提物却在促进吸收和抑制外排两个方面共同作用, 使二萜类生物碱的生物利用度明显增加.