Islas Selene R, Cuéllar-Cruz Mayra
Instituto de Ciencias Aplicadas y Tecnología, Universidad Nacional Autónoma de México, Circuito Exterior S/N, Ciudad Universitaria, Ciudad de México 04510, México.
Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta S/N, Col. Noria Alta, C.P. 36050 Guanajuato, Guanajuato, México.
ACS Omega. 2021 Dec 15;6(51):35629-35640. doi: 10.1021/acsomega.1c05415. eCollection 2021 Dec 28.
The Precambrian era is called the first stage of the Earth history and is considered the longest stage in the geological time scale. Despite its duration, several of its environmental and chemical characteristics are still being studied. It is an era of special relevance not only for its duration but also because it is when a set of conditions gave rise to the first organism. This pioneer organism has been proposed to have been formed by a mineral and an organic part. A chemical element suggested to have been part of the structure of this cell is iron. However, what special characteristic does iron have with respect to other chemical elements to be proposed as part of this first cell? To answer this and other questions, it is indispensable to have a model that will allow extrapolating the first chemical structures of the pioneer organism formed in the Precambrian. In this context, for several decades, in vitro structures chemically formed by silica-carbonates have been synthetized, called biomorphs, because they could emulate living organisms and might resemble primitive organisms. It has been inferred that because biomorphs form structures with characteristic morphologies, they could resemble the microfossils found in the cherts of the Precambrian. Aiming at providing some insight on how iron contributed to the formation of the chemical structures of the primitive organism, we evaluated how iron contributes to the morphology and chemical-crystalline structure during the synthesis of these compounds under different conditions found in the primitive atmosphere. Experimentally, synthesis of biomorphs was performed at four different atmospheric conditions including UV light, nonionizing microwave radiation (NIR-mw), water steam (WS), and CO in the presence of Fe, Fe, and Fe/Fe, obtaining 48 different conditions. The produced biomorphs were observed under scanning electron microscopy (SEM). Afterward, their chemical composition and crystalline structure were analyzed through Raman and IR spectroscopy.
前寒武纪时代被称为地球历史的第一阶段，被认为是地质时间尺度中最长的阶段。尽管其持续时间很长，但它的一些环境和化学特征仍在研究中。这个时代具有特殊的重要性，不仅因为它的持续时间，还因为正是在这个时期，一系列条件导致了第一种生物的出现。有人提出这种先驱生物是由矿物和有机部分组成的。一种被认为是这个细胞结构一部分的化学元素是铁。然而，相对于其他被提议作为这个第一个细胞一部分的化学元素，铁有什么特殊特征呢？为了回答这个以及其他问题，拥有一个能够推断前寒武纪形成的先驱生物的最初化学结构的模型是必不可少的。在这种背景下，几十年来，已经合成了由二氧化硅 - 碳酸盐化学形成的体外结构，称为生物形态，因为它们可以模拟生物体，并且可能类似于原始生物。据推断，由于生物形态形成具有特征形态的结构，它们可能类似于在前寒武纪燧石中发现的微化石。为了深入了解铁如何促成原始生物化学结构的形成，我们评估了在原始大气中发现的不同条件下，铁在这些化合物合成过程中对形态和化学 - 晶体结构的贡献。通过实验，在包括紫外线、非电离微波辐射（NIR - mw）、水蒸气（WS）和一氧化碳（CO），且存在铁（Fe）、亚铁（Fe²⁺）以及铁/亚铁（Fe/Fe²⁺）的四种不同大气条件下进行生物形态的合成，得到48种不同条件。在扫描电子显微镜（SEM）下观察所产生的生物形态。之后，通过拉曼光谱和红外光谱分析它们的化学成分和晶体结构。
