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61.
Ulrike Endesfelder Sebastian van de Linde Steve Wolter Markus Sauer Prof. Dr. Mike Heilemann Dr. 《Chemphyschem》2010,11(4):836-840
Subdiffraction‐resolution imaging by subsequent localization of single photoswitchable molecules can achieve a spatial resolution in the range of ～20 nm with moderate excitation intensities, but have so far been too slow for imaging faster dynamics in biology. Herein, we introduce a novel approach for video‐like subdiffraction microscopy based on rapid and reversible photoswitching of commercially available organic carbocyanine fluorophores. With the present concept, we demonstrate in vitro studies on the motility of fluorophore‐labeled actin filaments along myosin II. Actin filaments were densely labeled with carbocyanine fluorophores, and the gliding velocity adjusted by the concentration of ATP. At imaging frame rates of ～100 Hz, only 100 consecutive frames are sufficient to generate a single high‐resolution image of moving actin filaments with a lateral resolution of ～30 nm. A video‐like sequence is generated from individual reconstructed images by additionally applying a sliding window algorithm. We measured velocities of individual actin filaments of up to ～0.18 μm s?1, observed strong bending and disruption of filaments as well as locally immobile fragments. 相似文献
62.
糖尿病(DM)不同阶段胃动力紊乱研究 总被引：1，自引：0，他引：1
目的 探讨糖尿病 (DM )在不同阶段胃动力紊乱产生的规律 .方法 已确诊糖尿病病人 2 7例 ,糖尿病病人按其有无胃肠症状及其他糖尿病合并症分为两组 ,有胃肠症状同时伴有其他糖尿病合并症组 18例 ,无胃肠症状组 9例 ,同时选 2 0例正常人作对照 .用核素法对糖尿病 (DM )不同阶段胃排空功能的变化进行观察 .结果 有胃肠症状或合并其他脏器并发症的DM病人 12 0min近端胃存留率为 (33.72± 3.6 ) % ,较正常人 (2 3.16± 2 .0 2 ) %(P =0 .0 8)及无胃肠症状DM病人 (17.5 4± 3.0 8) % (P <0 .0 0 5 )增加 ,全胃和近端胃t1/2 分别为 (91.4 6± 9.2 8)min和 (81.87± 8.2 4 )min ,比正常人的 (5 5 .7± 3.6 8)min(P <0 .0 0 5 )和 (5 0 .2 9± 3.5 1)min(P <0 .0 1)明显延长 ;早期无胃肠症状或仅有轻度三多一少症状的DM病人的近端胃排空速率为 (1.10± 0 .12 ) % ,与正常人 (0 .0 8±0 .0 4 ) %相比明显增加 (P <0 .0 5 ) ,12 0min近端胃存留率为 (17.5 4± 3.0 8) % ,与正常人的 (2 3.16± 2 .0 2 ) %比较明显减少 (P =0 .0 6 ) .结论 不同阶段糖尿病患者胃排空功能状态不同 ,DM胃排空异常可能从近端胃开始 相似文献
63.
对9－10月龄的后备北极公狐的精液进行了冷冻观测,结果表明：I号稀释液经冷冻保存（－196℃）3年,其解冻活率达45％．5％葡萄糖作为解冻液明显好于葡－柠解冻液,2．9％柠檬酸钠液不适于北极狐冷冻精 液,干解冻优于湿解冻。 相似文献
64.
大黄鱼精子冷冻复苏后活力和超微结构的变化 总被引：3，自引：0，他引：3
大黄鱼精子以甘油为冷冻保存剂,经冷冻-解冻复苏后观察精子的活力和超微结构变化,并进行人工授精,观察冻精的受精能力.实验结果表明,冷冻精子的活力较高(83.1±6.2)%.大部分冷冻精子结构完整,进行人工授精可以获得较高的受精率(71.5±11.6)%.与鲜精对照组比较,仍存在差异(P<0.05).部分冷冻-解冻后的精子结构出现异常,畸形率达到29.3%(P<0.01).较常见的异常是精子质膜膨胀或破损,核膜消失,染色质解体,线粒体嵴消失,轴丝断裂成许多段等.冷冻精子结构异常可能是冻精解冻复苏后精子活力和受精力下降的主要原因. 相似文献
65.
In 2003, Mogilner and Verzi proposed a one-dimensional model on the crawling movement of a nematode sperm cell. Under certain conditions, the model can be reduced to a moving boundary problem for a single equation involving the length density of the bundled filaments inside the cell. It follows from the results of Choi, Lee and Lui (2004) that this simpler model possesses traveling cell solutions. In this paper, we show that the spectrum of the linear operator, obtained from linearizing the evolution equation about the traveling cell solution, consists only of eigenvalues and there exists such that if is a real eigenvalue, then . We also provide strong numerical evidence that this operator has no complex eigenvalue.
66.
通过大鼠眶额叶微量注射给药,记录胃内压(Intragastric pressure,IGP),观察胃运动变化的方法,研究了眶额叶多巴胺(dopamine,DA)对胃运动调节的神经机制.结果显示,眶额叶注射DA10μg,胃内压显著升高;眶额叶单独注射DA D1受体阻断剂SCH 2μg(SCH23390,SCH),胃内压降低.眶额叶注射SCH 2μg,能阻断DA升高胃内压的作用;眶额叶注射利陪酮(Risperidon)2μg,可升高胃内压,增强胃运动.但利陪酮却不能阻断DA升高胃内压的作用;切断双侧膈下迷走神经,眶额叶注射DA增加胃内压的作用被消除.以上各组中胃收缩频率均无明显变化.实验结果表明,眶额叶内DA能增大胃内压,增强胃运动,DA对胃内压及胃运动的增强作用主要是通过D1受体介导,经过迷走神经传出. 相似文献
67.
《中国物理 B》2021,30(9):90505-090505
Cell migration in anisotropic microenvironment plays an important role in the development of normal tissues and organs as well as neoplasm progression, e.g., osteogenic differentiation of embryonic stem cells was facilitated on stiffer substrates, indicating that the mechanical signals greatly affect both early and terminal differentiation of embryonic stem cells. However, the effect of anisotropy on cell migration dynamics, in particular, in terms of acceleration profiles which is important for recognizing dynamics modes of cell migration and analyzing the regulation mechanisms of microenvironment in mechanical signal transmission, has not been systematically investigated. In this work, we firstly rigorously investigate and quantify the differences between persistent random walk and anisotropic persistent random walk models based on the analysis of cell migration trajectories and velocity auto-covariance function, both qualitatively and quantitatively. Secondly, we introduce the concepts of positive and negative anisotropy based on the motility parameters to study the effect of anisotropy on acceleration profiles, especially the nonlinear decrease and non-monotonic behaviors. We particularly elaborate and discuss the mechanisms, and physical insights of non-monotonic behaviors in the case of positive anisotropy,focusing on the force exerted on migrating cells. Finally, we analyze two types of in vitro cell migration experiments and verify the universality of nonlinear decrease and the consistence of non-monotonic behaviors with numerical results.We conclude that the anisotropy of microenvironment is the cause of the non-monotonic and nonlinear dynamics, and the anisotropic persistent random walk can be as a suitable tool to analyze in vitro cell migration with different combinations of motility parameters. Our analysis provides new insights into the dynamics of cell migration in complex microenvironment,which also has implications in tissue engineering and cancer research. 相似文献
68.
Ya Tian ;Guoqing Xie 《Discrete and continuous dynamical systems》2024,29(6):2727-2748
In this paper, we deal with the following two-species competition system with signal-dependent motility and indirect signal consumption$ left{ {begin{array}{*{20}{l}} {{u_t} = Delta left( {{gamma _1}left( w right)u} right) + {mu _1}uleft( {1 - u - {a_1}v} right),quad }&{x in Omega ,quad }&{t > 0,} {{v_t} = Delta left( {{gamma _2}left( w right)v} right) + {mu _2}vleft( {1 - v - {a_2}u} right),quad }&{x in Omega ,quad }&{t > 0,} {{w_t} = Delta w - wz,quad }&{x in Omega ,quad }&{t > 0,} {{z_t} = Delta z - z + u + v,quad }&{x in Omega ,quad }&{t > 0,} end{array}} right. $under homogeneous Neumann boundary conditions in a smooth bounded domain $ Omega in {mathbb{R}^2} $, where the parameters $ {mu _i}, {a_i} $ are positive constants for $ i = 1, 2 $, and the motility function $ {gamma _i}left( w right) left( {i = 1, 2} right) $ satisfies the following assumptions:$ {gamma _i}left( w right) in {C^3}left( {left[ {0, infty } right)} right), {gamma _i}left( w right) > 0, text{ and }{gamma _i}^prime left( w right) le 0. $By some prior estimates, we obtain the global classical solution of this model for any $ {mu _i} left( {i = 1, 2} right) $. In addition, using the Lyapunov function, we also obtain the large time behavior of this model, as described below.● If $ {a_1}, {a_2} in left( {0, 1} right) $, then the solution $ left( {u, v, w, z} right) $ exponentially converges to $ left( {frac{{1 - {a_1}}}{{1 - {a_1}{a_2}}}, frac{{1 - {a_2}}}{{1 - {a_1}{a_2}}}, 0, frac{{2 - {a_1} - {a_2}}}{{1 - {a_1}{a_2}}}} right) $ as $ t to infty $;● If $ {a_1} > 1 > {a_2} > 0 $ and $ {a_1}{a_2} < 1 $, then the solution $ left( {u, v, w, z} right) $ exponentially converges to $ left( {0, 1, 0, 1} right) $ as $ t to infty $;● If $ {a_1} = 1 > {a_2} > 0 $, then the solution $ left( {u, v, w, z} right) $ algebraically converges to $ left( {0, 1, 0, 1} right) $ as $ t to infty $. 相似文献
69.
70.
细菌中的第二信使环二鸟苷酸(c-di-GMP)对细菌的运动性有调节作用.c-di-GMP调控鞭毛的生物合成、菌毛形成和菌毛蛋白的组成,以及其他一些与运动相关的蛋白的合成.细菌的运动性与其毒力、致病性、粘附性、趋化性、生物膜组成等密切相关.在革兰氏阴性细菌中,关于c-di-GMP的信号通路的研究较为清晰,而在革兰氏阳性细菌中,关于该信号转导通路的研究较少.此外,有关c-di-GMP的信号通路的研究主要集中在病原菌.该文主要综述了一些常见病原菌中c-di-GMP对其运动性的调控机制,为研究其他细菌c-di-GMP信号通路提供思路. 相似文献