Fisher P R
Microbiology Department, La Trobe University, Bundoora, Melbourne, Victoria, Australia.
Semin Cell Biol. 1990 Apr;1(2):87-97.
The behaviour of Dictyostelium discoideum amoebae has been studied in natural cAMP waves and in controlled spatial and temporal gradients. Chemoattractant gradients induce responses which indicate that amoebae spatially compare concentration increases at different points on the cell surface. This allows them to respond to the relative spatial and temporal gradients in a manner that is little affected by the absolute attractant concentration over several orders of magnitude. The changes in turning behaviour, motility and morphology that are induced by attractant gradients are consistent with transduction of stimuli into two intracellular signals - one activating and the other inhibiting pseudopodium formation. The former measures the present attractant concentration at particular points on the cell surface - the local, current signal. The latter measures the average attractant concentration over the whole cell surface during the recent past - the global, past signal. Both signals may be part of a normal pseudopodium autoactivation and inhibition system responsible for amoeboid morphology and motility. Attractants could modulate this system to generate the complex behavioural responses observed.
已在自然的环磷酸腺苷（cAMP）波以及可控的空间和时间梯度中研究了盘基网柄菌变形虫的行为。趋化因子梯度诱导的反应表明，变形虫在空间上比较细胞表面不同点的浓度增加情况。这使它们能够以一种在几个数量级上几乎不受绝对趋化因子浓度影响的方式对相对空间和时间梯度做出反应。趋化因子梯度诱导的转向行为、运动性和形态变化与刺激转导为两种细胞内信号一致——一种激活而另一种抑制伪足形成。前者测量细胞表面特定点处当前的趋化因子浓度——局部当前信号。后者测量近期整个细胞表面的平均趋化因子浓度——全局过去信号。这两种信号可能都是负责变形虫形态和运动性的正常伪足自动激活和抑制系统的一部分。趋化因子可以调节这个系统以产生观察到的复杂行为反应。
