PDF(Pubmed)
Abstract：
The signs of climate change are undeniable, and the impact of these changes on ecosystem function heavily depends on the response of microbes that underpin the food web. Antarctic ice shelf is a massive mass of floating ice that extends from the continent into the ocean, exerting a profound influence on global carbon cycles. Beneath Antarctic ice shelves, marine ice stores valuable genetic information, where marine microbial communities before the industrial revolution are archived. Here, in this proof-of-concept, by employing a combination of single-cell technologiesand metagenomics, we have been able to sequence frozen microbial DNA (≈300 years old) stored in the marine ice core B15 collected from the Filchnner-Ronne Ice Shelf. Metagenomic data indicated that Proteobacteria and Thaumarchaeota (e.g., Nitrosopumilus spp.), followed by Actinobacteria (e.g., Actinomarinales), were abundant. Remarkably, our data allow us to \"travel to the past\" and calibrate genomic and genetic evolutionary changes for ecologically relevant microbes and functions, such as Nitrosopumilus spp., preserved in the marine ice (≈300 years old) with those collected recently in seawater under an ice shelf (year 2017). The evolutionary divergence for the ammonia monooxygenase gene amoA involved in chemolithoautotrophy was about 0.88 amino acid and 2.8 nucleotide substitution rate per 100 sites in a century, while the accumulated rate of genomic SNPs was 2,467 per 1 Mb of genome and 100 years. Whether these evolutionary changes remained constant over the last 300 years or accelerated during post-industrial periods remains an open question that will be further elucidated.
OBJECTIVE: Several efforts have been undertaken to predict the response of microbes under climate change, mainly based on short-term microcosm experiments under forced conditions. A common concern is that manipulative experiments cannot properly simulate the response of microbes to climate change, which is a long-term evolutionary process. In this proof-of-concept study with a limited sample size, we demonstrate a novel approach yet to be fully explored in science for accessing genetic information from putative past marine microbes preserved under Antarctic ice shelves before the industrial revolution. This potentially allows us estimating evolutionary changes as exemplified in our study. We advocate for gathering a more comprehensive Antarctic marine ice core data sets across various periods and sites. Such a data set would enable the establishment of a robust baseline, facilitating a better assessment of the potential effects of climate change on key genetic signatures of microbes.
OBJECTIVE: Several efforts have been undertaken to predict the response of microbes under climate change, mainly based on short-term microcosm experiments under forced conditions. A common concern is that manipulative experiments cannot properly simulate the response of microbes to climate change, which is a long-term evolutionary process. In this proof-of-concept study with a limited sample size, we demonstrate a novel approach yet to be fully explored in science for accessing genetic information from putative past marine microbes preserved under Antarctic ice shelves before the industrial revolution. This potentially allows us estimating evolutionary changes as exemplified in our study. We advocate for gathering a more comprehensive Antarctic marine ice core data sets across various periods and sites. Such a data set would enable the establishment of a robust baseline, facilitating a better assessment of the potential effects of climate change on key genetic signatures of microbes.
摘要：
气候变化的迹象是不可否认的，这些变化对生态系统功能的影响在很大程度上取决于支撑食物网的微生物的反应。南极冰架是大量的浮冰，从大陆延伸到海洋，对全球碳循环产生深远的影响。在南极冰架下面，海洋冰储存有价值的遗传信息，工业革命前的海洋微生物群落被存档。这里,在这个概念证明中，通过结合单细胞技术和宏基因组学，我们已经能够对从Filchnner-Ronne冰架收集的海洋冰芯B15中存储的冷冻微生物DNA（约300岁）进行测序。宏基因组数据表明变形杆菌和Thaumarchaurota(例如，Nitrosopumilusspp.),其次是放线菌(例如，Actinomarinales),丰富。值得注意的是,我们的数据使我们能够“旅行到过去”，并校准与生态相关的微生物和功能的基因组和遗传进化变化，如Nitrosopumilusspp.,保存在海洋冰中（约300年），最近在冰架下的海水中收集（2017年）。在一个世纪中，参与化学自养的氨单加氧酶基因amoA的进化差异约为每100个位点0.88个氨基酸和2.8个核苷酸取代率，而基因组SNP的累积率为2,467/1Mb基因组和100年。这些进化变化在过去300年中保持不变还是在后工业时期加速，仍然是一个有待进一步阐明的问题。
目的：已经进行了一些努力来预测气候变化下微生物的响应，主要基于强迫条件下的短期微观实验。一个普遍的问题是，操纵性实验无法正确模拟微生物对气候变化的反应，这是一个长期的进化过程。在这个样本量有限的概念验证研究中，我们展示了一种新的方法，该方法尚未在科学中得到充分探索，可以从工业革命之前保存在南极冰架下的假定的过去海洋微生物中获取遗传信息。这可能使我们能够估计我们研究中所示例的进化变化。我们主张在各个时期和地点收集更全面的南极海洋冰芯数据集。这样的数据集将能够建立一个稳健的基线，促进更好地评估气候变化对微生物关键遗传特征的潜在影响。
目的：已经进行了一些努力来预测气候变化下微生物的响应，主要基于强迫条件下的短期微观实验。一个普遍的问题是，操纵性实验无法正确模拟微生物对气候变化的反应，这是一个长期的进化过程。在这个样本量有限的概念验证研究中，我们展示了一种新的方法，该方法尚未在科学中得到充分探索，可以从工业革命之前保存在南极冰架下的假定的过去海洋微生物中获取遗传信息。这可能使我们能够估计我们研究中所示例的进化变化。我们主张在各个时期和地点收集更全面的南极海洋冰芯数据集。这样的数据集将能够建立一个稳健的基线，促进更好地评估气候变化对微生物关键遗传特征的潜在影响。
