生物谷報道：以往我們的常識告訴我們只有具備完整神經系統(tǒng)的生物才可以主動預知環(huán)境的改變而作好應變準備,?？墒敲绹樟炙诡D大學的科學家近日研究表明細菌也具有某種形式的學習記憶能力,，能夠預先判斷環(huán)境的變化而做出反應。
研究人員利用計算機模型模擬了細菌的進化,，并在實驗室中培育大腸桿菌：首先將溫度從25攝氏度提高到37攝氏度,，然后將氧含量從20%降低到零。研究人員監(jiān)控了幾百代細菌的反應,，結果發(fā)現(xiàn),，幾周之后，細菌已經可以預料氧氣的下降,，即溫度一改變它們就會調整自己的代謝,。這說明，大腸桿菌能夠發(fā)展出將高溫（如人類口腔內）與缺氧（如人類腸道內）建立聯(lián)系的能力,。
近百年來,，關于細菌行為的流行觀點是動態(tài)平衡（homeostasis），即認為細菌對環(huán)境刺激的反應是以一種作用-反作用的方式進行的,。這一研究結果則顛覆了以往的認知,。這是細菌具有聯(lián)想學習的首個證據，這種反應與巴甫洛夫條件反射作用（條件反射訓練后,，狗聞鈴聲便分泌過量唾液）相似,。當然，這并不是說單細胞的細菌與狗或人具有相同的學習方式,。研究醫(yī)院表示,，人或狗的聯(lián)想學習跨越整個生命周期，并且包括對腦部神經元之間連接強度的修正；而細菌的學習要經過很長時間的進化過程,，包括基因網絡之間連接的改變,。
此次研究對于處理細菌感染和抗藥性具有潛在的意義。另外,，預見細菌的行為可能還有助于指導釀造等依賴它們的工業(yè)過程,。這項研究的報告5月8日在線發(fā)表于Science雜志。（生物谷www.bioon.com）
生物谷推薦原始出處：
Science,，DOI: 10.1126/science.1154456,，Ilias Tagkopoulos，Saeed Tavazoie
Anticipatory Behavior Within Microbial Genetic Networks
Ilias Tagkopoulos 1, Yir-Chung Liu 2, Saeed Tavazoie 2*
1 Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA.; Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA.
2 Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA.; Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
* To whom correspondence should be addressed.
Saeed Tavazoie , E-mail: [email protected]
These authors contributed equally to this work.
We question whether homeostasis alone adequately explains microbial responses to environmental stimuli, and explore the capacity of intra-cellular networks for predictive behavior in a fashion similar to metazoan nervous systems. We show that in silico biochemical networks, evolving randomly under precisely defined complex habitats, capture the dynamical, multi-dimensional structure of diverse environments by forming internal models that allow prediction of environmental change. We provide evidence for such anticipatory behavior by revealing striking correlations of Escherichia coli transcriptional responses to temperature and oxygen perturbations—precisely mirroring the co-variation of these parameters upon transitions between the outside world and the mammalian gastrointestinal-tract. We further show that these internal correlations reflect a true associative learning paradigm, since they show rapid de-coupling upon exposure to novel environments.
