BIOPHYSICAL MECHANISMS OF CHEMOTAXIS

这个子项目是利用资源的许多研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 子项目的主要研究者可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， NCRR赠款不直接向子项目或子项目工作人员提供资金。 趋化性是细胞感知并向更高浓度化学物质方向移动的能力，是免疫反应的组成部分。此外，它在伤口愈合、血管生成和胚胎发生中起关键作用。盘基网柄阿米巴是一种社会性阿米巴，是真核细胞的模型系统，在过去的二十年里得到了广泛的研究。在我们的实验中，我们探测和定量测量的初始趋化反应的单个Dictyosteoblastoma细胞的信号转导网络的这个关键组成部分，在响应于重复的时空脉冲的化学引诱物的定位动态。我们发现，单细胞的反应是非常可重复的脉冲到脉冲。相比之下，我们观察到一个大的变化，从细胞到细胞的趋化反应，即使在人口中的不同细胞暴露于相同的脉冲。虽然平均而言，细胞群找到了脉冲的正确方向，但在响应的方向和幅度上观察到了显著的变化。通过测量cAMP分子的外部浓度，定量地探索噪声和细胞个体性的来源。我们观察到，在定向传感机制的可靠性是不受限制的外部cAMP分子的数量少，噪声不减少时，外部cAMP分子增加了2个数量级。旨在更好地理解趋化机制的其他研究将利用通过软光刻技术产生的微流体装置来产生各种时空化学梯度。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Chemotaxis, the ability of the cell to sense and move in the direction of higher concentration of chemicals, is an integral part of immune response. Additionally it plays a key role in wound healing, angiogenesis, and embryogenesis. Dictyostelium discoideum, a model system for eukaryotic cells, is a social amoeba and has been studied extensively over the past twenty years. In our experiments, we probe and quantitatively measure the initial chemotactic response of single Dictyostelium cells by quantifying the localization dynamics of this key component of signaling transduction network in response to repeated spatio-temporal pulses of chemoattractant. We find that the response of a single cell is very reproducible from pulse-to-pulse. In contrast, we observe a large variability in the chemotactic response from cell-to-cell even when different cells in population are exposed to the same pulse. Although on average a population of cells finds the correct direction of the pulse, a significant variability is observed in the direction and the magnitude of the response. Origins of the noise and cell individuality by quantitatively are explored by measuring the external concentration of the cAMP molecules. We observe that the reliability in the directional sensing mechanism is not limited by the low number of external cAMP molecules and the noise does not decrease when the external cAMP molecules increases by 2 orders of magnitude. Additional studies aimed at better understanding the chemotaxis mechanism will utilize microfluidic devices produced via soft lithography techniques to generate a variety of spatio-temporal chemical gradients.