Project 2_2: Repose to Spatial Gradients

Requirement

• 假设chemoattractant在x方向有一个均匀的梯度，重新用MATLAB写一个模拟100个以上的 E.Coli 在chemoattractant梯度下细胞运动的程序，大家定要互相交流。
• 对每个细胞的离它的出发点的距离随时间变化进行分析包括距离和距离平方，并对所有细胞进行平均，在x和y方向分别进行分析，描述并解释结果。

Analysis

Howard C.Berg inserted one of Adler's capillary tubes through the side wall of a tracking chamber and followed cells in gradients of serine and aspartate. The result proved that E.Coli extends runs that are favorable( that carry cells up the gradient of an attractant) but fails to shorten runs that are not (that carry cells donws such a gradient). The random walk becomes biased, the bias is large enough to enable a cell to move up a gradient at about 10% of its run speed. But tumbles have precisely the same effect whether a cell swims in a gradient or not, they just occur with different frequencies.[1]So, Shortting the frequent of tumbling or tumbling time of single E.Coli can make sence.

Frist, we try to low the frequency of tumble in hill function to sence to chemoattractant. $ \theta=\frac{K_d}{K_d+C^n}$. But it similar with prat1.

Reference and Reading List

1. E.Coli in Motion, p33. Howar C.Berg(2003).
2. http://dufour.mmg.msu.edu/research.html (Nice reference)