BIOPHYSICAL MECHANISMS OF CHEMOTAXIS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 趋化性，即细胞感知和向更高浓度的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、血管生成和胚胎发育中起着关键作用。盘基网柄菌是真核细胞的模型系统，是一种社会阿米巴，在过去的二十年里得到了广泛的研究。在我们的实验中，我们通过量化信号转导网络中这一关键组件对重复的化学诱导剂时空脉冲的响应来探索和定量测量单个Dictyostelials细胞的初始趋化反应。我们发现单个电池的响应从一个脉冲到另一个脉冲具有很好的重复性。相反，我们观察到，即使人群中的不同细胞暴露在相同的脉冲下，细胞间的趋化反应也有很大的变异性。尽管平均而言，一群细胞找到了脉冲的正确方向，但在反应的方向和大小上观察到了显著的变异性。通过测量cAMP分子的外部浓度，定量地探讨了噪声的来源和细胞的个性。我们观察到，定向传感机制的可靠性不受外部cAMP分子数量较少的限制，并且当外部cAMP分子增加2个数量级时，噪声并不降低。旨在更好地了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控器件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. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. 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.