Protection of the DNA from Selected Species of Five Kingdoms in Nature by Ba(II), Sr(II), and Ca(II) Silica–Carbonates: Implications about Biogenicity and Evolving from Prebiotic Chemistry to Biological Chemistry

Abstract

The origin of life on Earth is associated with the Precambrian era, in which the existence of a large diversity of microbial fossils has been demonstrated. Notwithstanding, despite existing evidence of the emergence of life many unsolved questions remain. The first question could be as follows: Which was the inorganic structure that allowed isolation and conservation of the first biomolecules in the existing reduced conditions of the primigenial era? Minerals have been postulated as the ones in charge of protecting theses biomolecules against the external environment. There are calcium, barium, or strontium silica–carbonates, called biomorphs, which we propose as being one of the first inorganic structures in which biomolecules were protected from the external medium. Biomorphs are structures with different biological morphologies that are not formed by cells, but by nanocrystals; some of their morphologies resemble the microfossils found in Precambrian cherts. Even though biomorphs are unknown structures in the geological registry, their similarity with some biological forms, including some Apex fossils, could suggest them as the first “inorganic scaffold” where the first biomolecules became concentrated, conserved, aligned, and duplicated to give rise to the pioneering cell. However, it has not been documented whether biomorphs could have been the primary structures that conserved biomolecules in the Precambrian era. To attain a better understanding on whether biomorphs could have been the inorganic scaffold that existed in the primigenial Earth, the aim of this contribution is to synthesize calcium, barium, and strontium biomorphs in the presence of genomic DNA from organisms of the five kingdoms in conditions emulating the atmosphere of the Precambrian era and that CO2 concentration in conditions emulating current atmospheric conditions. Our results showed, for the first time, the formation of the kerogen signal, which is a marker of biogenicity in fossils, in the biomorphs grown in the presence of DNA. We also found the DNA to be internalized into the structure of biomorphs.

Influence of Different Types of Clay Minerals on the Shape and Form of Silica-Carbonates (Biomorphs) of Ca(II), Ba(II), and Sr(II)

“…In the biomorphs with phosphorite, the fungus-type morphology was observed (Figure F), and finally with quartz, α-helices were obtained (Figure G). These morphologies are some of those identified in the current conditions of CO 2 concentrations. ,, …”

“…[38][39][40]65,66 The barium or strontium biomorphs are not only important for the morphologies they adopt but also because it has been postulated that, even before the first biomolecule appeared, in the waters of the primigenial era, objects were formed that seem to be fossils but of inorganic origin, 67 which could have been the biomorphs; but as indicated by our research team, they possibly were not dated and, therefore, have been kept invisible. 44 To emulate and know the morphology that the first inorganic structures of the Precambrian could have adopted, which later gave rise to fossils, barium or strontium biomorphs were synthetized at a high concentration (5% (v/v) CO 2 ), emulating the Precambrian era conditions, and at the current atmospheric era in the presence of six different clays. The control barium biomorphs at 5% CO 2 presented a sphere-type polycrystalline morphology (Figure 3A).…”

“…These morphologies are some of those identified in the current conditions of CO 2 concentrations. 38,39,44 The different morphologies obtained for the barium or strontium biomorphs in conditions emulating the Precambrian era (5% (v/v) CO 2 ) as compared to the current atmospheric conditions (STP) evidence that indeed biomorphs could be the cherts of the Precambrian.…”

“…Some of these morphologies resemble some of the microfossils found in the Precambrian cherts. ,− Recently, our research team demonstrated that biomorphs could be considered to have been the first inorganic frameworks, in which the formed protobiomolecules became concentrated, conserved, aligned, and duplicated to give rise to the pioneer cell, and proposed that biomorphs are a reminiscence of the Precambrian cherts. The fact that they have not been dated as a fossil registry could have been because biomorphs were the ones to be actually formed, and their inclusion in sedimentary rocks is rather a biomineralization process through epitaxial growth. − Epitaxy is a type of crystal growth between two different crystal phases. , However, it has not been documented whether biomorphs are a consequence of the dissolution of clays in alkaline environments (rich in alkaline earth metals) during the early stages of the Earth. The latter would foster the hypothesis that biomorphs or cherts existed since that era.…”

“…The fact that they have not been dated as a fossil registry could have been because biomorphs were the ones to be actually formed, and their inclusion in sedimentary rocks is rather a biomineralization process 44 through epitaxial growth. 45−47 Epitaxy is a type of crystal growth between two different crystal phases.…”