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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Evolutionary genomics of ecological specialization.
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Evolutionary genomics of ecological specialization.

机译：生态专业化的进化基因组学。

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摘要

We used a combination of genomic techniques to monitor chromosomal evolution across hundreds of generations as Escherichia coli adapted to growth-limiting concentrations of either lactulose, methyl-galactoside, or a 72:28 mixture of the two. DNA microarrays identified 8 unique duplications and 16 unique deletions among 42 evolvants from 23 chemostat experiments. Each mutation was confirmed by sequencing PCR-amplified flanking genomic DNA and, except for one deletion, an insertion sequence was found at the break point. vPCR of insertion sequences identified these same mutations and 16 additional insertions (all confirmed by sequencing). The pattern of genomic evolution is highly reproducible. Statistical analyses show that duplications at lac and mutations in mgl are adaptations specific to lactulose and to methyl-galactoside, respectively. Adaptation to mixed sugars is characterized by similar mutations, but lac duplications and mgl mutations usually arise in different backgrounds, producing ecologicalspecialists for each sugar. This suggests that an antagonistic pleiotropic tradeoff between duplications at lac and mutations in mgl retards the evolution of generalists. Other mutations that repeatedly appear in replicate experiments are adaptations to the chemostat environment and are not specific to one or the other sugar.
机译：当大肠杆菌适应乳果糖，甲基半乳糖苷或两者的72:28混合物的生长限制浓度时，我们使用基因组技术的组合来监测数百代的染色体进化。 DNA微阵列从23个化学恒温实验中鉴定出42个进化产物中的8个独特重复和16个独特缺失。通过对PCR扩增的侧翼基因组DNA进行测序来确认每个突变，除了一个缺失，在突变点发现了插入序列。插入序列的vPCR鉴定出这些相同的突变和16个其他插入（均通过测序确认）。基因组进化的模式是高度可复制的。统计分析表明，lac重复和mgl突变分别适应于乳果糖和甲基半乳糖苷。适应混合糖的特征是相似的突变，但是lac重复和mgl突变通常出现在不同的背景下，从而为每种糖产生了生态专家。这表明在lac重复和mgl突变之间的对抗性多效性折衷阻碍了多面手的发展。在重复实验中反复出现的其他突变是对恒化器环境的适应，而不是特定于一种或另一种糖。

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