Buried alive: extracellular polymeric substances promote clay mineral templating of live eukaryotic algae

The Proterozoic fossil record of early eukaryotes is a crucial archive for major events in the early evolution of life, yet it is composed almost entirely of non-biomineralized organisms which required special environmental conditions to be preserved. Emerging work has shown that clay minerals can enhance preservation, and fossils of early eukaryotes are closely associated with clay minerals. Thus, understanding the role of clay minerals in organic preservation directly affects our interpretation of the early eukaryotic fossil record. Here, we perform taphonomic experiments using green algae and clay mineral substrates to investigate how clay minerals ‘template’ protist-grade organisms and enhance their preservation potential. We show that clay mineral templating occurs on geologically instantaneous timescales (days-weeks)—while organisms are still alive—via interactions with extracellular polymeric substances. Furthermore, we show that the extent and rate of templating is affected both by both the presence or absence of light and mineralogy. These results point towards a secular bias, which in turn likely influences our view of evolution during the Proterozoic. This dataset contains (3) spreadsheets from SEM, ICP-MS, and pH data, and one zip file with (6) .csv files containing relative abundances of cell types (healthy/clay-coated healthy/clay-coated unhealthy). Files and variables File: SEMdata_raw.xlsx Description: This spreadsheet contains data from SEM-EDS point counts of elemental abundances, shown in Figure S3. File: ICPMS.xlsx Description: This spreadsheet contains data from ICP-MS measurements of cation concentrations, shown in Figure 8. File: pH.xlsx Description: This spreadsheet contains a replicate list and pH measurements from each sampling interval, shown in Figure 8. File: Image_analysis.zip Description: This zip folder contains (6) .csv files which contain relative abundances of cell types (healthy/clay-coated healthy/clay-coated unhealthy), shown in Figure 4.早期真核生物的元古代（Proterozoic）化石记录是生命早期演化重大事件的关键档案，但其几乎完全由依赖特殊环境条件才能得以保存的非矿化生物组成。新兴研究表明，黏土矿物可提升化石保存效果，且早期真核生物化石与黏土矿物存在密切关联。因此，厘清黏土矿物在有机质保存中的作用，直接影响我们对早期真核生物化石记录的解读。 本研究以绿藻与黏土矿物基质开展埋藏学实验，旨在探究黏土矿物如何对原生生物级生物产生模板化作用，并提升其保存潜力。研究发现，黏土矿物的模板化作用可在地质瞬时尺度（数天至数周）内，于生物仍存活时通过与胞外聚合物（extracellular polymeric substances）的相互作用完成。此外，本研究还发现，模板化作用的程度与速率同时受光照条件与矿物成分的影响。上述结果指向一种长期系统性偏差，而该偏差或进一步影响我们对元古代演化历程的认知。 本数据集包含3份分别对应扫描电子显微镜（SEM）、电感耦合等离子体质谱（ICP-MS）及pH数据的电子表格，以及1个压缩包，内含6份.csv格式文件，文件包含细胞类型（健康细胞/黏土包覆健康细胞/黏土包覆异常细胞）的相对丰度信息。 文件与变量 文件：SEMdata_raw.xlsx 描述：该电子表格包含扫描电镜能谱（SEM-EDS）点计数法测得的元素丰度数据，对应补充材料图S3。 文件：ICPMS.xlsx 描述：该电子表格包含电感耦合等离子体质谱（ICP-MS）测得的阳离子浓度数据，对应正文图8。 文件：pH.xlsx 描述：该电子表格包含重复样品列表与各采样区间的pH测量数据，对应正文图8。 文件：Image_analysis.zip 描述：该压缩文件夹包含6份.csv格式文件，内含细胞类型（健康细胞/黏土包覆健康细胞/黏土包覆异常细胞）的相对丰度数据，对应正文图4。