Decision making improves sperm chemotaxis in the presence of noise
Decision making improves sperm chemotaxis in the presence of noise
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DOI：
10.1371/journal.pcbi.1006109
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发表时间：
2018-04-01
影响因子：
4.3
通讯作者：
Friedrich, Benjamin M.
中科院分区：
文献类型：
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作者：
Kromer, Justus A.;Maercker, Steffen;Friedrich, Benjamin M.
为了感知周围环境，细胞依赖于受噪声干扰的感官输入。在进行趋化性的细胞中，这种噪声源于在低趋化因子浓度下信号分子的随机结合。我们揭示了趋化转向速度与因化学输入信号中噪声放大而产生的方向波动强度之间的一种基本关系。这种关系意味着在缓慢且可靠的转向与快速但不太可靠的转向之间存在一种权衡。我们表明，在这两种转向模式之间动态切换能够显著增加找到目标的概率，比如精子细胞找到卵子。在没有噪声的情况下，这种决策没有优势，但当化学信号可检测但信噪比很低时是有益的。后者适用于距目标中等距离的情况，此时信号分子被稀释，从而定义了一个细胞必须穿越的“噪声区”。我们的结果解释了在最近关于海胆精子趋化性的实验中观察到的决策行为。更广泛地说，我们的理论展示了决策是如何使趋化因子通过动态调整有偏随机游走的持久长度来应对梯度感知中的高水平噪声的。
To navigate their surroundings, cells rely on sensory input that is corrupted by noise. In cells performing chemotaxis, such noise arises from the stochastic binding of signalling molecules at low chemoattractant concentrations. We reveal a fundamental relationship between the speed of chemotactic steering and the strength of directional fluctuations that result from the amplification of noise in a chemical input signal. This relation implies a trade-off between steering that is slow and reliable, and steering that is fast but less reliable. We show that dynamic switching between these two modes of steering can substantially increase the probability to find a target, such as an egg to be found by sperm cells. This decision making confers no advantage in the absence of noise, but is beneficial when chemical signals are detectable, yet characterized by low signal-to-noise ratios. The latter applies at intermediate distances from a target, where signalling molecules are diluted, thus defining a 'noise zone' that cells have to cross. Our results explain decision making observed in recent experiments on sea urchin sperm chemotaxis. More generally, our theory demonstrates how decision making enables chemotactic agents to cope with high levels of noise in gradient sensing by dynamically adjusting the persistence length of a biased random walk.