乍一看,，微生物似乎受其環(huán)境以及該環(huán)境中可能發(fā)生的任何變化支配,。它們的命運似乎只能是對所發(fā)生的事件做出反應。所以,，關于細菌和酵母在一系列變化遵從一個重復模式的環(huán)境中都能夠將一個刺激與對某種未來環(huán)境的適當反應聯(lián)系起來的發(fā)現(xiàn),，有點兒出乎意料。在一個與巴甫洛夫條件反射在某些方面有相似之處,、但卻依賴于調控網絡和自然選擇而非認知的過程中,，穿過腸道的大腸桿菌及經過不同發(fā)酵階段的酵母會“預測”它們下面要經歷什么，并對代謝通道進行組織,，來應對其所要經歷的東西,。大腸桿菌此后會僅僅重復暴露于一系列環(huán)境中的第一個，甚至“忘記”它們所受過的訓練并失去條件反射,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 460, 220-224 (9 July 2009) | doi:10.1038/nature08112
Adaptive prediction of environmental changes by microorganisms
Amir Mitchell1, Gal H. Romano2, Bella Groisman1, Avihu Yona1, Erez Dekel3, Martin Kupiec2, Orna Dahan1,5 & Yitzhak Pilpel1,4,5
1 Department of Molecular Genetics, Weizmann Institute of Science Rehovot 76100, Israel
2 Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv 69978, Israel
3 Department of Molecular Cell Biology, Weizmann Institute of Science Rehovot 76100, Israel
4 Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
5 These authors contributed equally to this work.
Natural habitats of some microorganisms may fluctuate erratically, whereas others, which are more predictable, offer the opportunity to prepare in advance for the next environmental change. In analogy to classical Pavlovian conditioning, microorganisms may have evolved to anticipate environmental stimuli by adapting to their temporal order of appearance. Here we present evidence for environmental change anticipation in two model microorganisms, Escherichia coli and Saccharomyces cerevisiae. We show that anticipation is an adaptive trait, because pre-exposure to the stimulus that typically appears early in the ecology improves the organism's fitness when encountered with a second stimulus. Additionally, we observe loss of the conditioned response in E. coli strains that were repeatedly exposed in a laboratory evolution experiment only to the first stimulus. Focusing on the molecular level reveals that the natural temporal order of stimuli is embedded in the wiring of the regulatory network—early stimuli pre-induce genes that would be needed for later ones, yet later stimuli only induce genes needed to cope with them. Our work indicates that environmental anticipation is an adaptive trait that was repeatedly selected for during evolution and thus may be ubiquitous in biology.
