Rosenzweig R F, Sharp R R, Treves D S, Adams J
Department of Biology, University of Michigan, Ann Arbor 48109.
Genetics. 1994 Aug;137(4):903-17. doi: 10.1093/genetics/137.4.903.
Populations of Escherichia coli initiated with a single clone and maintained for long periods in glucose-limited continuous culture, become polymorphic. In one population, three clones were isolated and by means of reconstruction experiments were shown to be maintained in stable polymorphism, although they exhibited substantial differences in maximum specific growth rates and in glucose uptake kinetics. Analysis of these three clones revealed that their stable coexistence could be explained by differential patterns of the secretion and uptake of two alternative metabolites acetate and glycerol. Regulatory (constitutive and null) mutations in acetyl-coenzyme A synthetase accounted for different patterns of acetate secretion and uptake seen. Altered patterns in glycerol uptake are most likely explained by mutations which result in quantitative differences in the induction of the glycerol regulon and/or structural changes in glycerol kinase that reduce allosteric inhibition by effector molecules associated with glycolysis. The evolution of resource partitioning, and consequent polymorphisms which arise may illustrate incipient processes of speciation in asexual organisms.
以单个克隆起始并在葡萄糖限制的连续培养中长时间维持的大肠杆菌群体，会变得多态。在一个群体中，分离出了三个克隆，通过重建实验表明它们以稳定的多态性维持，尽管它们在最大比生长速率和葡萄糖摄取动力学方面表现出显著差异。对这三个克隆的分析表明，它们的稳定共存可以通过两种替代代谢物乙酸盐和甘油的分泌和摄取的差异模式来解释。乙酰辅酶A合成酶中的调节（组成型和无效）突变导致了观察到的乙酸盐分泌和摄取的不同模式。甘油摄取模式的改变很可能是由导致甘油调节子诱导的定量差异和/或甘油激酶结构变化的突变所解释的，这些变化减少了与糖酵解相关的效应分子的变构抑制。资源分配的进化以及随之出现的多态性可能说明了无性生物物种形成的初始过程。
