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首页> 外文期刊>Journal of Theoretical Biology >Adaptive changes in bacteria: a consequence of nonlinear transitions in chromosome topology?
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Adaptive changes in bacteria: a consequence of nonlinear transitions in chromosome topology?

机译：细菌的适应性变化：染色体拓扑中非线性转变的结果吗？

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Adaptive changes in bacteria are generally considered to result from random Mutations selected by the environment. This interpretation is challenged by the non-randomness of genomic changes observed following ageing or starvation in bacterial colonies. A theory of adaptive targeting of sequences for enzymes involved in DNA transactions is proposed here. It is assumed that the sudden leakage of cAMP consecutive to starvation induces a rapid drop in the ATP/ADP ratio that inactivates the homeostasis in control of the level of DNA supercoiling. This phase change enables the emergence of local modifications in chromosome topology in relation to the missing metabolites, a first stage in expression of an adaptive status in which DNA transactions are induced. The nonlinear perspective proposed here is homologous to that already suggested for adaptation of pluricellular organisms during their development. In both cases, phases of robustness in regulation networks for genetic expression are interspaced by critical periods of breakdown of the homeostatic regulations during which, through isolation of nodes from a whole network, specific changes with adaptive value may locally occur. (C)2004 Elsevier Ltd. All rights reserved.
机译：通常认为细菌的适应性变化是由环境选择的随机突变引起的。细菌菌落老化或饥饿后观察到的基因组变化的非随机性，对这一解释提出了挑战。本文提出了DNA交易中涉及的酶的序列自适应靶向理论。可以推测，紧挨饥饿的cAMP突然泄漏会引起ATP / ADP比值的快速下降，从而使体内稳态失活，从而无法控制DNA超螺旋的水平。该相变使得与缺失的代谢物有关的染色体拓扑中局部修饰的出现成为可能，这是表达DNA交易的适应性状态的第一阶段。本文提出的非线性观点与多细胞生物在发育过程中的适应性已经提出的观点相同。在这两种情况下，用于基因表达的调控网络的健壮阶段都由稳态调控的关键性破坏期隔开，在此期间，通过将节点与整个网络隔离，可能会局部发生具有适应性价值的特定变化。 （C）2004 Elsevier Ltd.保留所有权利。

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