NeuO: a Fluorescent Chemical Probe for Live Neuron Labeling

To address existing limitations in live neuron imaging, we have developed NeuO , a novel cell‐permeable fluorescent probe with an unprecedented ability to label and image live neurons selectively over other cells in the brain. NeuO enables robust live neuron imaging and isolation in vivo and in vitro across species; its versatility and ease of use sets the basis for its development in a myriad of neuronal targeting applications.     

LMI-based robust adaptive synchronization of FitzHugh-Nagumo neurons with unknown parameters under uncertain external electrical stimulation

This Letter addresses a nonlinear robust adaptive control that utilizes linear matrix inequalities for asymptotic synchronization of two coupled chaotic FitzHugh-Nagumo neurons under unknown parameters and uncertain stimulation current amplitudes and phase shifts. Synchronization of chaotic neurons using the proposed control method through numerical simulation is demonstrated.     

Electric Field-induced dynamical evolution of spiral wave in the regular networks of Hodgkin-Huxley neurons

An additional gradient force is often used to simulate the polarization effect induced by the external field in the reaction-diffusion systems. The polarization effect of weak electric field on the regular networks of Hodgkin-Huxley neurons is measured by imposing an additive term V_E on physiological membrane potential at the cellular level, and the dynamical evolution of spiral wave subjected to the external electric field is investigated. A statistical variable is defined to study the dynamical evolution of spiral wave due to polarization effect. In the numerical simulation, 40000 neurons placed in the 200 × 200 square array with nearest neighbor connection type. It is found that spiral wave encounters death and the networks become homogeneous when the intensity of electric field exceeds the critical value, otherwise, spiral wave keeps alive completely. On the other hand, breakup of spiral wave occurs as the intensity of electric field exceeds the critical value in the presence of weak channel noise, otherwise, spiral wave keeps robustness to the external field completely. The critical value can be detected from the abrupt changes in the curve for factors of synchronization vs. control parameter, a smaller factor of synchronization is detected when the spiral wave keeps alive.     

镧对仔鼠嗅感觉神经元分化中β—Ⅲ微管蛋白的作用

为观察发育期氯化镧暴露对仔鼠嗅觉功能及β-Ⅲ微管蛋白表达的影响,将16只Wistar孕鼠随机分为两组（对照组、氯化镧组）,对照组母鼠饮用蒸馏水,氯化镧组饮用0．25％氯化镧溶液;仔鼠出生后25d采用嗅觉迷宫试验检测仔鼠嗅觉功能的差异;于出生后28d采用免疫荧光和免疫印迹观察仔鼠β-Ⅲ微管蛋白在嗅上皮的表达变化。结果表明,氯化镧组仔鼠在嗅觉迷宫试验寻找食物的时间较对照组长,差异具有统计学意义（P〈0．05）;氯化镧组下调仔鼠嗅上皮β-Ⅲ微管蛋白在嗅感觉神经元的表达。提示镧暴露损害子代嗅觉功能,可能与镧损害嗅上皮β-Ⅲ微管蛋白的表达有关。     

Conducting swift heavy ion track networks

In this paper, the electronic behavior of conducting swift heavy ion track networks is studied. On the one hand, the transient conductivity of ion tracks in metal oxides on silicon in status nascendi is exploited for this purpose, and on the other hand, conducting tracks are produced by ion irradiation of insulating membranes (either self-supported or deposited onto silicon substrates), subsequent etching and finally inserting conducting materials of whatever provenience (in this work preferentially electrolytes). Depending on their manufacture, the conducting tracks either act as electronically active or passive elements. When applying a voltage across individual tracks in the first case, one observes current spikes with negative differential resistances. These tracks interact among themselves, leading to phase-locked synchronous coupled oscillations with complex patterns that are quite similar to those emerging from neural networks. The other case corresponds to networks of electronically passive conducting tracks which become overall electronically active only through their collective interactions. Though the aforementioned effects had been experimentally described earlier, they are re-visited here to make clear that the corresponding systems have to be considered as being artificial neural networks. On this occasion, some new findings are added.     

The roles of glycosphingolipids in the proliferation and neural differentiation of mouse embryonic stem cells

Glycosphingolipids including gangliosides play important regulatory roles in cell proliferation and differentiation. UDP-glucose:ceramide glucosyltransferase (Ugcg) catalyze the initial step in glycosphingolipids biosynthesis pathway. In this study, Ugcg expression was reduced to approximately 80% by short hairpin RNAs (shRNAs) to evaluate the roles of glycosphingolipids in proliferation and neural differentiation of mouse embryonic stem cells (mESCs). HPTLC/immunofluorescence analyses of shRNA-transfected mESCs revealed that treatment with Ugcg-shRNA decreased expression of major gangliosides, GM3 and GD3. Furthermore, MTT and Western blot/immunofluorescence analyses demonstrated that inhibition of the Ugcg expression in mESCs resulted in decrease of cell proliferation (P < 0.05) and decrease of activation of the ERK1/2 (P < 0.05), respectively. To further investigate the role of glycosphingolipids in neural differentiation, the embryoid bodies formed from Ugcg-shRNA transfected mESCs were differentiated into neural cells by treatment with retinoic acid. We found that inhibition of Ugcg expression did not affect embryoid body (EB) differentiation, as judged by morphological comparison and expression of early neural precursor cell marker, nestin, in differentiated EBs. However, RT-PCR/immunofluorescence analyses showed that expression of microtubule- associated protein 2 (MAP-2) for neurons and glial fibrillary acidic protein (GFAP) for glial cells was decreased in neural cells differentiated from the shRNA-transfected mESCs. These results suggest that glycosphingolipids are involved in the proliferation of mESCs through ERK1/2 activation, and that glycosphingolipids play roles in differentiation of neural precursor cells derived from mESCs.     

弱激光诱导神经元兴奋性改变的实验研究

利用全细胞膜片钳技术研究弱激光诱导下大鼠海马CA3区锥体神经元兴奋性.实验结果显示：弱激光作用使神经元钠通道激活电位向超极化方向移动,钠电流幅度增大,且这种增大作用具有电压依赖性和可逆性.激光作用显著影响钠电流稳态激活与失活特性，对照组和照射组通道半数激活电压分别为(-4414±528)mV和(-5655±614)mV(n=8,P<001)，半数失活电压分别为(-6902±1031)mV和(-5660±897)mV(n=8, P<0     

Thermodynamically Stable,Photoreversible Pharmacology in Neurons with One‐ and Two‐Photon Excitation

Photoswitchable bioprobes enable bidirectional control of cell physiology with different wavelengths of light. Many current photoswitches use cytotoxic UV light and are limited by the need for constant illumination owing to thermal relaxation in the dark. Now a photoswitchable tetrafluoroazobenzene(4FAB)‐based ion channel antagonist has been developed that can be efficiently isomerized in two separate optical channels with visible light. Importantly, the metastable cis configuration showed very high stability in the dark over the course of days at room temperature. In neurons, the 4FAB antagonist reversibly blocks voltage‐gated ion channels with violet and green light. Furthermore, photoswitching could also be achieved with two‐photon excitation yielding high spatial resolution. 4FAB probes have the potential to enable long‐term biological studies where both ON and OFF states can be maintained in the absence of irradiation.     

DEVELOPMENTAL STUDIES OF ELECTRICAL PROPERTIES IN CULTURED RAT BRAIN NEURONS

The rat brain neurons isolated from 15—17-day embryos were grown in dissociated cell culture and maintained in vitro for 3 weeks, The developmental process of the neurons was observed from the early stage of development in terms of passive and active electrical parameters and their changes induced by perfusion of ionic channel blockers.The neurons' development could be morphologically divided into stages Ⅰ (from seedling to 5 days), Ⅱ (7—11 days), Ⅲ (12—20 days)andlV (21—22 days). The relative values of resting membrane potentials (RMP) for stages Ⅰ, Ⅱ, Ⅲ and Ⅳ were 1, 3.46, 4.07 and 6.54, respectively; the corresponding values of input resistance (Rin) were 10 1.48, 2.53 and 4.56, respectively. The current-voltage relationship in stages Ⅱ and Ⅲ was exponential in the direction of depolarization and the Rin's change with time was nearly linear. Spontaneous activities increased with prolongation of culture and the amplitude of evoked action potentials reached the maximum during stages Ⅲ and