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Field: Microbiology
Article Title: Genotypic diversity within a natural coastal bacterioplankton population
Authors: Thompson, JR;Pacocha, S;Pharino, C;Klepac-Ceraj, V;Hunt, DE;Benoit, J;Sarma-Rupavtarm, R;Distel, DL;Polz, MF
Journal: SCIENCE
Volume: 307
Issue: 5713
Page: 1311-1313

Q： Why do you think your paper is highly cited?

A：This study has been cited often because it provides an important environmental context for the expanding fields of microbial genomics and community ecology by quantifying the magnitude of coexisting genomic diversity within a microbial population. In addition, we hope that this work helps to motivate further studies exploring the emergent properties of populations composed of diverse constituents and the ecological and evolutionary mechanisms that give rise to such diversity.

Q： Does it describe a new discovery, methodology, or synthesis of knowledge?

A：Our observation of extreme genomic diversity coexisting within a population (where every microbe in 1000 individuals of a population has a unique genome that can differ in size by up to 1 Mb or ~20%) helps explain the difficulty of assembling genomes from environmental shotgun libraries. In addition, such extreme genomic diversity within populations warrants caution in the extrapolation of the environmental relevance of microbial model systems based on single strains.

Q： Could you summarize the significance of your paper in layman?s terms?

A：Asexual reproduction in bacteria has been long thought to provide a constraint on the evolution of diversity within microbial populations?this is in contrast to sexual reproduction within populations where children share unique combinations of genetic features derived from each parent. However, this study reveals an unprecedented level of diversity within a microbial population that suggests evolution within bacteria occurs by both sexual and asexual mechanisms.

Moreover, the coexistence of such diversity suggests that the unique combinations of genetic traits in each member of the population do not confer significant competitive advantages within the context of the environment observed.

Q： How did you become involved in this research, and were any problems encountered along the way?

A：Our lab has a long-standing interest in microbial ecology and evolution. We were surprised by the high genomic diversity present in environmental isolates of a Vibrio species obtained as part of a seasonal dynamics study of Vibrio diversity in the temperate New England coastal waters (sampling New England coastal waters during the winter certainly posed a challenge!). We decided to follow up on this observation during the following year and found a consistent trend of high genomic diversity associated with this and other species throughout the sampling season.

Janelle Thompson
Post Doctoral Associate
The Polz Lab
Department of Civil and Environmental Engineering
Massachusetts Institute of Technology (MIT)
Cambridge, MA, USA

Martin Polz, Ph.D.
Principal Investigator
The Polz Lab
Assistant Professor of Civil and Environmental Engineering
Department of Civil and Environmental Engineering
Massachusetts Institute of Technology (MIT)
Cambridge, MA, USA


领域：微生物学

题目：天然海岸浮游菌群的基因多样性

Q：你觉得为什么你的论文得到了高度引用呢？

A：这个研究经常被引用是因为，通过在微生物群体中定量分析共生的染色体组的多样性，这个研究为微生物染色体组和群落生态学的扩增提供了一个重要的环境联系。此外，我们希望这个工作能激起更多的人进一步研究探索种群的新出现的性质，这个种群是由多样性的组成以及产生这种多样性的生态的进化机制共同构成的。

Q：研究是否描述了一个新的发现，方法学或知识的综合呢？

A：我们对共存于一个种群的染色体组多样性的观察（在这个种群里，每1000个细菌就有一个特殊的基因组，这个基因组可以在大小上作出区别，能精确到1 Mb或达到20%）可以帮助解释评估环境这个库里的基因组的困难。此外，种群中的染色体组多样性提示我们应比较谨慎，并可推断微生物模型系统的的环境适应性。

Q：你能从一个外行的角度来简单的说一下你的论文的重要的意义吗？

A：人们早已发现细菌的无性繁殖在微生物种群的多样性进化方面具有一定的局限性。这与种群中的有性繁殖相反，在有性繁殖的生物群体里子女获得了来自于父母独特的遗传特征的结合。然而，这份研究揭示了一个在微生物群体中史无先例的多样性水平，这意味着细菌的进化既有有性繁殖也有无性繁殖。

更进一步来说，多样性的共存表明种群里每一个成员的遗传特性的特殊结合与所在的环境条件相比，并无重要的竞争优势。

Q：你是如何开始进行这个研究以及在研究过程中遇到过什么问题吗？

A：我们的实验室一直对微生物生态学和进化有很浓的兴趣。我们很惊讶的发现了环境中隔离的弧菌染色体组具有高度多样性，这个弧菌物种是在气候温和的新英格兰沿海的海水中（从冬天的新英格兰沿海取样可是一个挑战！）、作为一种弧菌多样性季节的动力学研究的一部分而获得的。我们决定在以后的几年中顺着这个观察继续研究下去，联合弧菌以及从各个季节获得的所有取样样本我们发现了染色体组高度多样性的持续现象。


编辑：西门吹血