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AbstractSpace exploration and research are uncovering the potential for terrestrial life to survive in outer space, as well as the environmental factors that affect life during interplanetary transfer. The presence of methane in the Martian atmosphere suggests the possibility of methanogens, either extant or extinct, on Mars. Understanding how methanogens survive and adapt under space-exposed conditions is crucial for understanding the implications of extraterrestrial life. In this article, we discuss methanogens as model organisms for obtaining energy transducers and producing methane in a simulated Martian environment. We also explore the chemical evolution of cellular composition and growth maintenance to support survival in extraterrestrial environments. Neutral selective pressure is imposed on the chemical composition of cellular components to increase cell survival and reduce growth under physiological conditions. Energy limitation is an evolutionary driver of macromolecular polymerization, growth maintenance, and survival fitness of methanogens. Methanogens grown in a Martian environment may exhibit global alterations in their metabolic function and gene expression at the system scale. A space systems biology approach would further elucidate molecular survival mechanisms and adaptation to a drastic outer space environment. Therefore, identifying a genetically stable methanogenic community is essential for biomethane production from waste recycling to achieve sustainable space-life support functions. [ABSTRACT FROM AUTHOR]

SO and SO2 are two potential candidates to trace the different evolutionary phases of the low-mass star-formation process. Here, we report observations of SO and SO2 along with their isotopologues, 34SO and 34SO2, respectively, in four distinct phases of the low-mass star-formation process (prestellar core, first hydrostatic core, Class 0, and Class I) with an unbiased survey carried out using the Institut de Radioastronomie Millimetrique (IRAM) 30 m telescope. Interestingly, the estimated abundances of SO and SO2 show an increasing trend from the prestellar phase to the Class 0 stage and then a decrease in the Class I phase. A similar trend is obtained for OCS and H2S. In contrast, the obtained SO/SO2 ratio decreases gradually from the prestellar core to the Class I stage. We have used the three-phase Rokko chemical code to explain our observations. The modeled abundances of SO and SO2 exhibit an increase within the inner region as the cold gas transforms into a hot gas. The modeled abundance ratio of SO to SO2 exhibits a notably high value in cold gas environments. This ratio decreases to less than 1 within the temperature range of 100-300 K and then increases to approximately 1 beyond 300 K. In the outer region, the simulated ratio consistently exceeds the value of 1. Our work is an observational testbed for modeling the chemistry of SO/SO2 during low-mass star formation. However, our findings may require more sample sources with higher resolution and a more robust model for validation. [ABSTRACT FROM AUTHOR]

SO and SO2 are two potential candidates to trace the different evolutionary phases of the low-mass star-formation process. Here, we report observations of SO and SO2 along with their isotopologues, 34SO and 34SO2, respectively, in four distinct phases of the low-mass star-formation process (prestellar core, first hydrostatic core, Class 0, and Class I) with an unbiased survey carried out using the Institut de Radioastronomie Millimetrique (IRAM) 30 m telescope. Interestingly, the estimated abundances of SO and SO2 show an increasing trend from the prestellar phase to the Class 0 stage and then a decrease in the Class I phase. A similar trend is obtained for OCS and H2S. In contrast, the obtained SO/SO2 ratio decreases gradually from the prestellar core to the Class I stage. We have used the three-phase Rokko chemical code to explain our observations. The modeled abundances of SO and SO2 exhibit an increase within the inner region as the cold gas transforms into a hot gas. The modeled abundance ratio of SO to SO2 exhibits a notably high value in cold gas environments. This ratio decreases to less than 1 within the temperature range of 100-300 K and then increases to approximately 1 beyond 300 K. In the outer region, the simulated ratio consistently exceeds the value of 1. Our work is an observational testbed for modeling the chemistry of SO/SO2 during low-mass star formation. However, our findings may require more sample sources with higher resolution and a more robust model for validation. [ABSTRACT FROM AUTHOR]

Male orchid bees are unique in the animal kingdom for making perfumes that function as sex pheromone. Males collect volatile chemicals from the environment in the neotropical forests, including floral and non-floral sources, creating complex but species-specific blends. Male orchid bees exhibit several adaptations to facilitate perfume collection and storage. When collecting volatile compounds, males apply lipid substances that they secrete from cephalic labial glands onto the fragrant substrate. These lipids help dissolve and retain the volatiles, similar to the process of 'enfleurage' in the traditional perfume industry. We investigated how the chemical composition of acquired perfume and labial gland secretions varied across the phylogeny of orchid bees, including 65 species in five genera from Central and South America. Perfumes showed rapid evolution as revealed by low overall phylogenetic signal, in agreement with the idea that perfume compounds diverge rapidly and substantially among closely related species due to their role in species recognition. A possible exception were perfumes in the genus Eulaema, clustering closely in chemospace, partly mediated by high proportions of carvone and trans-carvone oxide. Labial gland secretions, in contrast, showed a strong phylogenetic signal at the genus level, with secretions of Eufriesea and Exaerete dominated by fatty acids and Eulaema dominated by saturated acetates of chain lengths 12 to 16 C-atoms. Secretions of the majority of Euglossa were heavily dominated by one unsaturated long chain diacetate, (9Z)-Eicosen-1,20-diyldiacetate. However, we also identified few highly divergent species of Euglossa in four subclades (11 species) that appear to have secondarily replaced the diacetate with other compounds. In comparison with environment-derived perfumes, the evolution of labial gland secretion is much slower, likely constrained by the underlying biochemical pathways, but perhaps influenced by perfume-solvent chemical interactions. [ABSTRACT FROM AUTHOR]

Evolution requires selection. Molecular/chemical/preDarwinian evolution is no exception. One molecule must be selected over another for molecular evolution to occur and advance. Evolution, however, has no goal. The laws of physics have no utilitarian desire, intent or proficiency. Laws and constraints are blind to "usefulness." How then were potential multi-step processes anticipated, valued and pursued by inanimate nature? Can orchestration of formal systems be physico-chemically spontaneous? The purely physico-dynamic self-ordering of Chaos Theory and irreversible non-equilibrium thermodynamic "engines of disequilibria conversion" achieve neither orchestration nor formal organization. Natural selection is a passive and after-the-fact-of-life selection. Darwinian selection reduces to the differential survival and reproduction of the fittest already-living organisms. In the case of abiogenesis, selection had to be 1) Active, 2) Pre-Function, and 3) Efficacious. Selection had to take place at the molecular level prior to the existence of non-trivial functional processes. It could not have been passive or secondary. What naturalistic mechanisms might have been at play? [ABSTRACT FROM AUTHOR]

The prebiotic synthesis of peptides prior to ribosome-catalyzed processes remains an enigma. The synthesis of abiotic peptides from amino acids (AAs) is primarily constrained by high activation energies and unfavorable thermodynamics, necessitating the identification of plausible prebiotic alternatives for synthesizing prebiotic peptides. Here we present a plausible pathway to the formation of prebiotic peptides, wherein oligopeptides, oligopeptide amides, and cyclic oligopeptides can be directly synthesized from amino acid amides (AA-NH2) under wet–dry cycle conditions without the need for any enhancers. The subsequent investigation revealed that AA-NH2 demonstrated more favorable thermodynamic reaction effects than AAs in peptide formation. In contrast to the polymerization of AAs, the process of peptide formation through the polymerization of AA-NH2 was significantly simplified. Additionally, AA-NH2 was discovered to function as a “bridge” for the formation of peptides from AAs, thereby facilitating their participation in the synthesis of intricate peptide structures. On the basis of these findings, a plausible mechanism for the prebiotic origin network of peptides under primordial Earth conditions has been proposed. Overall, this research presents a plausible pathway for the generation of prebiotic peptides and peptide libraries within prebiotic environments.

Discharge plasmas, recognized as unique platforms for investigating the origins of chemical life, have garnered extensive interest for their potential to simulate prebiotic conditions. This paper embarks on a comprehensive overview of recent advancements in the plasma-enabled synthesis of life’s building blocks, charting the complex environmental parameters believed to have surrounded life’s inception. This discussion elaborates on the fundamental mechanisms of discharge plasmas and their likely role in fostering conditions necessary for the origin of life on early Earth. We consider a variety of chemical reactions facilitated by plasma, specifically the synthesis of vital organic molecules — amino acids, nucleobases, sugars, and lipids. Further, we delve into the impact of plasmas on prebiotic chemical evolution. We expect this review to open new horizons for future investigations in plasma-related prebiotic chemistry that could offer valuable insights for unraveling the mysteries of life's origin.

The creation of large information molecules may have played an essential role in the origins of life. In this study, we conducted slow freeze‐thaw (F/T) experiments to test the possibility of enhanced hybridization between the complementary sticky ends attached to kilobase‐sized DNA fragments at sub‐nanomolar concentrations. DNA fragments of 2‐ and 3‐kilobase pairs (kbp) with 50‐base complementary sticky ends that can form 5 kbp‐sized hybridization products were mixed. While simple incubation provided little hybridization product, significantly effective hybridization was observed after freezing and thawing at a controlled time rate (<0.3 K min−1), even with small DNA concentrations (<1 nM). Furthermore, slow thawing had a more effect on hybridization than slow freezing. The reaction efficiency was reduced by rapid thawing instead of slow thawing, suggesting that the eutectic phase concentration played an important role in hybridization. A slow F/T cycle was effective even for the hybridization reaction between two 10 kbp DNA fragments, which yielded a 20 kbp product at sub‐nanomolar concentrations. Repeating the slow F/T cycle significantly improved the reaction efficiency. The possible role of the F/T cycles in early Earth environments is discussed here. [ABSTRACT FROM AUTHOR]

SO and SO2 are two potential candidates to trace the different evolutionary phases of the low-mass star-formation process. Here, we report observations of SO and SO2 along with their isotopologues, 34SO and 34SO2, respectively, in four distinct phases of the low-mass star-formation process (prestellar core, first hydrostatic core, Class 0, and Class I) with an unbiased survey carried out using the Institut de Radioastronomie Millimetrique (IRAM) 30 m telescope. Interestingly, the estimated abundances of SO and SO2 show an increasing trend from the prestellar phase to the Class 0 stage and then a decrease in the Class I phase. A similar trend is obtained for OCS and H2S. In contrast, the obtained SO/SO2 ratio decreases gradually from the prestellar core to the Class I stage. We have used the three-phase Rokko chemical code to explain our observations. The modeled abundances of SO and SO2 exhibit an increase within the inner region as the cold gas transforms into a hot gas. The modeled abundance ratio of SO to SO2 exhibits a notably high value in cold gas environments. This ratio decreases to less than 1 within the temperature range of 100–300 K and then increases to approximately 1 beyond 300 K. In the outer region, the simulated ratio consistently exceeds the value of 1. Our work is an observational testbed for modeling the chemistry of SO/SO2 during low-mass star formation. However, our findings may require more sample sources with higher resolution and a more robust model for validation.

Homochirality is an obvious feature of life on Earth. On the other hand, extraterrestrial samples contain largely racemic compounds. The same is true for any common organic synthesis. Therefore, it has been a perplexing puzzle for decades how these racemates could have formed enantiomerically enriched fractions as a basis for the origin of homochiral life forms. Numerous hypotheses have been put forward as to how preferentially homochiral molecules could have formed and accumulated on Earth. In this article, it is shown that homochirality of the abiotic organic pool at the time of formation of the first self-replicating molecules is not necessary and not even probable. It is proposed to abandon the notion of a molecular ensemble and to focus on the level of individual molecules. Although the formation of the first self-replicating, most likely homochiral molecule, is a seemingly improbable event, on a closer look, it is almost inevitable that some homochiral molecules have formed simply on a statistical basis. In this case, the non-selective leap to homochirality would be one of the first steps in chemical evolution directly out of a racemic "ocean". Moreover, most studies focus on the chirality of the primordial monomers with respect to an asymmetric carbon atom. However, any polymer with a minimal size that allows folding to a secondary structure would spontaneously lead to asymmetric higher structures (conformations). Most of the functions of these polymers would be influenced by this inherently asymmetric folding. Furthermore, a concept of physical compartmentalization based on rock nanopores in analogy to nanocavities of digital immunoassays is introduced to suggest that complex cell walls or membranes were also not required for the first steps of chemical evolution. To summarize, simple and universal mechanisms may have led to homochiral self-replicating systems in the context of chemical evolution. A homochiral monomer pool is deemed unnecessary and probably never existed on primordial Earth. [ABSTRACT FROM AUTHOR]

Formaldehyde condensation in the presence of a mineral catalyst and under alkaline conditions is considered to be a ''messy'' chemical system due to its dependence on the complex chemical equilibrium between the reaction intermediates, which has a significant impact on the final products.This chemical system is extremely important in prebiotic chemistry and has been proposed as a potential pathway for carbohydrate formation in the early Earth. Saline and soda lakes are alkaline systems that could concentrate and accumulate a wide variety of ions (such as phosphate) and clay minerals, which can catalyze prebiotic chemical reactions. These geological environments have recently been suggested as ideal environments in which prebiotic chemical reactions could have occurred.This study uses Lake Alchichica in Mexico as a physicochemical analog of an early Archean saline lake to examine the stability of formaldehyde in these aqueous saline environments. Formaldehyde decomposes into sugar-like and CHO molecules in alkaline, high-salinity environments depending on the minerals phases present. As phosphate ion (HPO42−) is available in the aqueous medium, the results of our experiments also imply that phosphorylation processes may have occurred in these natural settings.

The article presents a modern protobiological theory based on the classical archetype. It connects the issues of origins of life with the theory of the hierarchy of matter and recognizes that error correction occurs within hierarchical and dynamic living systems. The paper briefly reproduces Morowitz-Smith prebiotic scenario. It highlights the importance of rTCA for theory, and the observation that the transition from a planet “without life” to a planet “with life” is a thermodynamic problem. Reflections on the philosophical foundations and worldview consequences of the theory are presented. The book and articles by the authors are crafted in a holistic approach and are critical towards the premature (and excessive) extrapolation of Darwinian selection as a means of explaining the process of abiogenesis.

The article presents the hypothesis of the origin of life. All the basic ideas of the 20th century research program in this area can be found there: the extrapolation of Darwinism into the area of chemical evolution, the influence of solar energy, the large “chemical possibilities” of carbon compounds, early heterotrophy, the gradual increase of organic purpose as a result of natural selection.

The role of evolutionary theory at the origin of life is an extensively debated topic. The origin and early development of life is usually separated into a prebiotic phase and a protocellular phase, ultimately leading to the Last Universal Common Ancestor. Most likely, the Last Universal Common Ancestor was subject to Darwinian evolution, but the question remains to what extent Darwinian evolution applies to the prebiotic and protocellular phases. In this review, we reflect on the current status of evolutionary theory in origins of life research by bringing together philosophy of science, evolutionary biology, and empirical research in the origins field. We explore the various ways in which evolutionary theory has been extended beyond biology; we look at how these extensions apply to the prebiotic development of (proto)metabolism; and we investigate how the terminology from evolutionary theory is currently being employed in state-of-the-art origins of life research. In doing so, we identify some of the current obstacles to an evolutionary account of the origins of life, as well as open up new avenues of research. [ABSTRACT FROM AUTHOR]

The fossil record demonstrates the preservation of porphyrins (e.g., heme) in organic sediments and the fossilized remains of animals. These molecules are essential components in modern metabolic processes, such as electron transport (cytochromes) and oxygen transport (hemoglobin), and likely originated before the emergence of life. The integration and adaptation of porphyrins and structurally similar molecules (e.g., chlorophylls) are key aspects in the evolution of energy production (i.e., aerobic respiration and photosynthesis) and complex life (i.e., eukaryotes and multicellularity). Here, we discuss the evolution and functional diversity of heme-bound hemoglobin proteins in vertebrates, along with the preservation of these molecules in the fossil record. By elucidating the pivotal role of these molecules in the evolution of life, this review lays the groundwork necessary to explore hemoglobin as a means to investigate the paleobiology of extinct taxa, including non-avian dinosaurs. [ABSTRACT FROM AUTHOR]

The article presents a modern protobiological theory based on the classical archetype. It connects the issues of origins of life with the theory of the hierarchy of matter and recognizes that error correction occurs within hierarchical and dynamic living systems. The paper briefly reproduces Morowitz-Smith prebiotic scenario. It highlights the importance of rTCA for theory, and the observation that the transition from a planet "without life" to a planet "with life" is a thermodynamic problem. Reflections on the philosophical foundations and worldview consequences of the theory are presented. The book and articles by the authors are crafted in a holistic approach and are critical towards the premature (and excessive) extrapolation of Darwinian selection as a means of explaining the process of abiogenesis. [ABSTRACT FROM AUTHOR]

The article presents the hypothesis of the origin of life. All the basic ideas of the 20th century research program in this area can be found there: the extrapolation of Darwinism into the area of chemical evolution, the influence of solar energy, the large "chemical possibilities" of carbon compounds, early heterotrophy, the gradual increase of organic purpose as a result of natural selection. [ABSTRACT FROM AUTHOR]

Asphalt in damp-heat and saline-alkali areas is prone to damage, which resulting in fatigue failure of the mixture. However, the aging damage of asphalt in these areas has not been paid enough attention, and there is a lack of effective evaluation method for asphalt's fatigue performance. In this paper, the base asphalt and SBS-modified asphalt were immersed in several solutions (water, NaCl and Na2CO3) to simulate aging conditions and the frequency sweep test was employed to determine the viscoelasticity properties of the asphalt. And the fatigue properties of the asphalt were analysed by the simplified viscoelastic continuum damage model. The microstructural and chemical evolution of asphalt was investigated by SEM, FTIR, the pH value and total organic carbon tests. After being immersed, the anti-deformation properties of two asphalts were strengthened. The solution erosion led to an increased loss rate of the integrity factor C*, and resulting in weakened fatigue properties of asphalt. The oxygen-containing functional group gradually increased with the extension of immersion. There were chemical interactions in addition to physical interface disruption during the immersion process. Moreover, the influence of Na2CO3 solution on asphalt ranked first due to the highest molar concentration of Na+ and the OH− produced by hydrolysis of ${\rm CO}_3^{2-}$ C O 3 2 − . [ABSTRACT FROM AUTHOR]

The origins of biopolymers pose fascinating questions in prebiotic chemistry. The marvelous assembly proficiencies of biopolymers suggest they are winners of a competitive evolutionary process. Sophisticated molecular assembly is ubiquitous in life where it is often emergent upon polymerization. We focus on the influence of molecular assembly on hydrolysis rates in aqueous media and suggest that assembly was crucial for biopolymer selection. In this model, incremental enrichment of some molecular species during chemical evolution was partially driven by the interplay of kinetics of synthesis and hydrolysis. We document a general attenuation of hydrolysis by assembly (i.e., recalcitrance) for all universal biopolymers and highlight the likely role of assembly in the survival of the 'fittest' molecules during chemical evolution. [ABSTRACT FROM AUTHOR]

Monoterpene indole alkaloids (MIAs) are endowed with high structural and spatial complexity and characterized by diverse biological activities. Given this complexity‐activity combination in MIAs, rapid and efficient access to chemical matter related to and with complexity similar to these alkaloids would be highly desirable, since such compound classes might display novel bioactivity. We describe the design and synthesis of a pseudo‐natural product (pseudo‐NP) collection obtained by the unprecedented combination of MIA fragments through complexity‐generating transformations, resulting in arrangements not currently accessible by biosynthetic pathways. Cheminformatic analyses revealed that both the pseudo‐NPs and the MIAs reside in a unique and common area of chemical space with high spatial complexity‐density that is only sparsely populated by other natural products and drugs. Investigation of bioactivity guided by morphological profiling identified pseudo‐NPs that inhibit DNA synthesis and modulate tubulin. These results demonstrate that the pseudo‐NP collection occupies similar biologically relevant chemical space that Nature has endowed MIAs with. [ABSTRACT FROM AUTHOR]

Homochirality is an obvious feature of life on Earth. On the other hand, extraterrestrial samples contain largely racemic compounds. The same is true for any common organic synthesis. Therefore, it has been a perplexing puzzle for decades how these racemates could have formed enantiomerically enriched fractions as a basis for the origin of homochiral life forms. Numerous hypotheses have been put forward as to how preferentially homochiral molecules could have formed and accumulated on Earth. In this article, it is shown that homochirality of the abiotic organic pool at the time of formation of the first self-replicating molecules is not necessary and not even probable. It is proposed to abandon the notion of a molecular ensemble and to focus on the level of individual molecules. Although the formation of the first self-replicating, most likely homochiral molecule, is a seemingly improbable event, on a closer look, it is almost inevitable that some homochiral molecules have formed simply on a statistical basis. In this case, the non-selective leap to homochirality would be one of the first steps in chemical evolution directly out of a racemic “ocean”. Moreover, most studies focus on the chirality of the primordial monomers with respect to an asymmetric carbon atom. However, any polymer with a minimal size that allows folding to a secondary structure would spontaneously lead to asymmetric higher structures (conformations). Most of the functions of these polymers would be influenced by this inherently asymmetric folding. Furthermore, a concept of physical compartmentalization based on rock nanopores in analogy to nanocavities of digital immunoassays is introduced to suggest that complex cell walls or membranes were also not required for the first steps of chemical evolution. To summarize, simple and universal mechanisms may have led to homochiral self-replicating systems in the context of chemical evolution. A homochiral monomer pool is deemed unnecessary and probably never existed on primordial Earth.

The formose reaction is a plausible prebiotic chemistry, famed for its production of sugars. In this work, we demonstrate that the Cannizzaro process is the dominant process in the formose reaction under many different conditions, thus necessitating a catalyst for the formose reaction under various environmental circumstances. The investigated formose reactions produce primarily organic acids associated with metabolism, a protometabolic system, and yield very little sugar left over. This is due to many of the acids forming from the degradation and Cannizaro reactions of many of the sugars produced during the formose reaction. We also show the heterogeneous Lewis-acid-based catalysis of the formose reaction by mineral systems associated with serpentinization. The minerals that showed catalytic activity include olivine, serpentinite, and calcium, and magnesium minerals including dolomite, calcite, and our Ca/Mg-chemical gardens. In addition, computational studies were performed for the first step of the formose reaction to investigate the reaction of formaldehyde, to either form methanol and formic acid under a Cannizzaro reaction or to react to form glycolaldehyde. Here, we postulate that serpentinization is therefore the startup process necessary to kick off a simple proto metabolic system—the formose protometabolic system. [ABSTRACT FROM AUTHOR]

Prebiotic processes required a reliable source of free energy and complex chemical mixtures that may have included sugars. The formose reaction is a potential source of those sugars. At moderate to elevated temperature and pH ranges, these sugars rapidly decay. Here it is shown that CaCO3-based chemical gardens catalyze the formose reaction to produce glucose, ribose, and other monosaccharides. These thin inorganic membranes are explored as analogs of hydrothermal vent materials—a possible place for the origin of life—and similarly exposed to very steep pH gradients. Supported by simulations of a simple reaction-diffusion model, this study shows that such gradients allow for the dynamic accumulation of sugars in specific layers of the thin membrane, effectively protecting formose sugar yields. Therefore, the formose reaction may be a plausible prebiotic reaction in alkaline hydrothermal vent environments, possibly setting the stage for an RNA world. [ABSTRACT FROM AUTHOR]

The fossil record demonstrates the preservation of porphyrins (e.g., heme) in organic sediments and the fossilized remains of animals. These molecules are essential components in modern metabolic processes, such as electron transport (cytochromes) and oxygen transport (hemoglobin), and likely originated before the emergence of life. The integration and adaptation of porphyrins and structurally similar molecules (e.g., chlorophylls) are key aspects in the evolution of energy production (i.e., aerobic respiration and photosynthesis) and complex life (i.e., eukaryotes and multicellularity). Here, we discuss the evolution and functional diversity of heme-bound hemoglobin proteins in vertebrates, along with the preservation of these molecules in the fossil record. By elucidating the pivotal role of these molecules in the evolution of life, this review lays the groundwork necessary to explore hemoglobin as a means to investigate the paleobiology of extinct taxa, including non-avian dinosaurs.

The role of evolutionary theory at the origin of life is an extensively debated topic. The origin and early development of life is usually separated into a prebiotic phase and a protocellular phase, ultimately leading to the Last Universal Common Ancestor. Most likely, the Last Universal Common Ancestor was subject to Darwinian evolution, but the question remains to what extent Darwinian evolution applies to the prebiotic and protocellular phases. In this review, we reflect on the current status of evolutionary theory in origins of life research by bringing together philosophy of science, evolutionary biology, and empirical research in the origins field. We explore the various ways in which evolutionary theory has been extended beyond biology; we look at how these extensions apply to the prebiotic development of (proto)metabolism; and we investigate how the terminology from evolutionary theory is currently being employed in state-of-the-art origins of life research. In doing so, we identify some of the current obstacles to an evolutionary account of the origins of life, as well as open up new avenues of research.

Numerous long-standing questions in origins-of-life research center on the history of biopolymers. For example, how and why did nature select the polypeptide backbone and proteinaceous side chains? Depsipeptides, containing both ester and amide linkages, have been proposed as ancestors of polypeptides. In this paper, we investigate cationic depsipeptides that form under mild dry-down reactions. We compare the oligomerization of various cationic amino acids, including the cationic proteinaceous amino acids (lysine, Lys; arginine, Arg; and histidine, His), along with nonproteinaceous analogs of Lys harboring fewer methylene groups in their side chains. These analogs, which have been discussed as potential prebiotic alternatives to Lys, are ornithine, 2,4-diaminobutyric acid, and 2,3-diaminopropionic acid (Orn, Dab, and Dpr). We observe that the proteinaceous amino acids condense more extensively than these nonproteinaceous amino acids. Orn and Dab readily cyclize into lactams, while Dab and Dpr condense less efficiently. Furthermore, the proteinaceous amino acids exhibit more selective oligomerization through their α-amines relative to their side-chain groups. This selectivity results in predominantly linear depsipeptides in which the amino acids are α-amine-linked, analogous to today's proteins. These results suggest a chemical basis for the selection of Lys, Arg, and His over other cationic amino acids for incorporation into proto-proteins on the early Earth. Given that electrostatics are key elements of protein-RNA and protein-DNA interactions in extant life, we hypothesize that cationic side chains incorporated into proto-peptides, as reported in this study, served in a variety of functions with ancestral nucleic acid polymers in the early stages of life.

This study focuses on the radiolysis (up to 36 kGy) of guanine and adenine (nitrogenous bases) adsorbed in hectorite and attapulgite to highlight the potential role of clays as protective agents against ionizing radiation in prebiotic processes. In this framework, the study investigated the nitrogenous bases’ behavior in two types of systems: a) aqueous suspension of adenine–clay systems and b) guanine–clay systems in the solid state. This research utilized spectroscopic and chromatographic techniques for its analytical purposes. Regardless of the reaction medium conditions, the results reveal that nitrogenous bases are stable under ionizing irradiation when adsorbed on both clays.

Reduced oxidation state phosphorus compounds may have been brought to the early Earth via meteorites or could have formed through geologic processes. These compounds could have played a role in the origin of biological phosphorus (P, hereafter) compounds. Reduced oxidation state P compounds are generally more soluble in water and are more reactive than orthophosphate and its associated minerals. However, to date no facile routes to generate C–O–P type compounds using reduced oxidation state P compounds have been reported under prebiotic conditions. In this study, we investigate the reactions between reduced oxidation state P compounds—and their oxidized products generated via Fenton reactions—with the nucleosides uridine and adenosine. The inorganic P compounds generated via Fenton chemistry readily react with nucleosides to produce organophosphites and organophosphates, including phosphate diesters via one-pot syntheses. The reactions were facilitated by NH4+ ions and urea as a condensation agent. We also present the results of the plausible stability of the organic compounds such as adenosine in an environment containing an abundance of H2O2. Such results have direct implications on finding organic compounds in Martian environments and other rocky planets (including early Earth) that were richer in H2O2 than O2. Finally, we also suggest a route for the sink of these inorganic P compounds, as a part of a plausible natural P cycle and show the possible formation of secondary phosphate minerals such as struvite and brushite on the early Earth. [ABSTRACT FROM AUTHOR]

How life emerged from inanimate matter is one of the most intriguing questions posed to modern science. Central to this research are experimental attempts to build systems capable of Darwinian evolution. RNA catalysts (ribozymes) are a promising avenue, in line with the RNA world hypothesis whereby RNA pre‐dated DNA and proteins. Since evolution in living organisms relies on template‐based replication, the identification of a ribozyme capable of replicating itself (an RNA self‐replicase) has been a major objective. However, no self‐replicase has been identified to date. Alternatively, autocatalytic systems involving multiple RNA species capable of ligation and recombination may enable self‐reproduction. However, it remains unclear how evolution could emerge in autocatalytic systems. In this review, we examine how experimentally feasible RNA reactions catalysed by ribozymes could implement the evolutionary properties of variation, heredity and reproduction, and ultimately allow for Darwinian evolution. We propose a gradual path for the emergence of evolution, initially supported by autocatalytic systems leading to the later appearance of RNA replicases. [ABSTRACT FROM AUTHOR]

Pseudo‐natural products (pseudo‐NPs) are de novo combinations of natural product (NP) fragments that define novel bioactive chemotypes. For their discovery, new design principles are being sought. Previously, pseudo‐NPs were synthesized by the combination of fragments originating from biosynthetically unrelated NPs to guarantee structural novelty and novel bioactivity. We report the combination of fragments from biosynthetically related NPs in novel arrangements to yield a novel chemotype with activity not shared by the guiding fragments. We describe the synthesis of the polyketide pseudo‐NP grismonone and identify it as a structurally novel and potent inhibitor of Hedgehog signaling. The insight that the de novo combination of fragments derived from biosynthetically related NPs may also yield new biologically relevant compound classes with unexpected bioactivity may be considered a chemical extension or diversion of existing biosynthetic pathways and greatly expands the opportunities for exploration of biologically relevant chemical space by means of the pseudo‐NP principle. [ABSTRACT FROM AUTHOR]

It is generally recognized that the evolution of the early Earth was affected by an external energy source: radiation from the early Sun. The hypothesis about the important role of natural radioactivity, as a source of internal energy in the evolution of the early Earth, is considered and substantiated in this work. The decay of the long-lived isotopes 232Th, 238U, 235U, and 40K in the Global Ocean initiated the oxygenation of the hydro- and atmosphere, and the abiogenesis. The content of isotopes in the ocean and the kinetics of their decay, the values of the absorbed dose and dose rate, and the efficiency of sea water radiolysis, as a function of time, were calculated. The ocean served as both a "reservoir" that collected components of the early atmosphere and products of their transformations, and a "converter" in which further chemical reactions of these compounds took place. Radical mechanisms were proposed for the formation of simple amino acids, sugars, and nitrogen bases, i.e., the key structures of all living things, and also for the formation of oxygen. The calculation results confirm the possible important role of natural radioactivity in the evolution of terrestrial matter, and the emergence of life. [ABSTRACT FROM AUTHOR]

The adsorption of thymine, a key pyrimidine base of deoxyribonucleic acid (DNA) on montmorillonite clay (Mnt) exchanged with metal ions (Mnt—M2+, M2+ = Fe2+, Co2+, Cu2+, Ca2+, and Mg2+) over a range of concentration (7.0 × 10–5 M to 12.0 × 10–5 M) and pH (4.0 – 9.0) at ambient temperature has been investigated in aqueous environment spectrophotometrically (UV, FTIR, XRD, SEM—EDX). The effectiveness of various adsorbents was determined in terms of percent (%) binding and Langmuir constants (KL and Xm) using Langmuir adsorption isotherm at their respective pH of maximum adsorption. Transition metal ions incorporated Mnt, particularly Fe2+ have shown better adsorption ability than alkaline earth metal ions. The present study reveals the significant role of divalent metal cation exchanged Mnt clay in the chemical evolution of biomolecules of genetic continuity and self-replication which might have occurred through the adsorption of thymine on and between their silicate layers to protect and achieve biocompatibility. [ABSTRACT FROM AUTHOR]

In accordance with the abiogenic hypothesis of the origin of oil, deposits formed as a result of degassing of the Earth, in particular, due to the interaction of mantle methane and its polycondensation products with elemental sulfur, are thermodynamically open systems. In open systems, self-organization processes are realized and a progressive evolution of the catalyst of the basic reaction occurs, accompanied by an increase in its activity and accumulation in the system. The predominance of vanadium in the trace element composition of sour oils may be due to its catalytic activity in the basic reaction of the formation of C–S bonds. [ABSTRACT FROM AUTHOR]

The elucidation of the mechanism of the chemical evolution of the universe is one of the most important themes in astrophysics. Polycyclic aromatic hydrocarbons (PAHs) provide a two-dimensional reaction field in a three-dimensional interstellar space. Additionally, PAHs play an important role as a model of graphene nanoflake (GNF) in materials chemistry. In the present review, we introduce our recent theoretical studies on the reactions of PAH and GNF with several molecules (or radicals). Furthermore, a hydrogen storage mechanism for alkali-doped GNFs and the molecular design of a reversible hydrogen storage device based on GNF will be introduced. Elucidating these reactions is important in understanding the chemical evolution of the universe and gives deeper insight into materials chemistry.

I If an upper bound i HT ht I is imposed on i HT ht I (so that the process terminates when i HT ht I ) then Lemma 1 implies that i HT ht I is certain to eventually hit i HT ht I . To see how this increases with increasing HT ht , Figure 3 shows the theoretical probability (solid lines) of an all- HT ht RAF against HT ht for different values of HT ht . Next, the algorithm stops when I exactly i HT ht molecular species have been produced (due to the I if i -statement at line 16). In other words, the probabilities HT ht could be considered some sort of reaction propensities. [Extracted from the article]

On the other hand, the surface area of montmorillonite is much greater than that of zirconium silicate and thus, the ASBVd(-):HHR binds on montmorillonite at a much lower density than on zirconium silicate; however, self-cleavage was also deactivated on montmorillonite. Since zirconium silicate is one of the oldest minerals on the ancient Earth, this study suggests that the role of minerals may have been important for the chemical evolution of RNA molecules from the very beginning of water emergence on the Hadean Earth. Keywords: hammerhead ribozyme; chemical evolution; mineral; adsorption; Hadean Earth; zirconium silicate; montmorillonite; Aerosil; sepiolite EN hammerhead ribozyme chemical evolution mineral adsorption Hadean Earth zirconium silicate montmorillonite Aerosil sepiolite 1689 16 11/17/22 20221101 NES 221101 1. The four minerals selected were aerosil silica, zirconium silicate, sepiolite, and montmorillonite, each of which are of prebiotic interest and/or possess unique characteristics. [Extracted from the article]

The origin of life on Earth required myriads of chemical and physical processes. These include the formation of the planet and its geological structures, the formation of the first primitive chemicals, reaction, and assembly of these primitive chemicals to form more complex or functional products and assemblies, and finally the formation of the first cells (or protocells) on early Earth, which eventually evolved into modern cells. Each of these processes presumably occurred within specific prebiotic reaction environments, which could have been diverse in physical and chemical properties. While there are resources that describe prebiotically plausible environments or nutrient availability, here, we attempt to aggregate the literature for the various physicochemical properties of different prebiotic reaction microenvironments on early Earth. We introduce a handful of properties that can be quantified through physical or chemical techniques. The values for these physicochemical properties, if they are known, are then presented for each reaction environment, giving the reader a sense of the environmental variability of such properties. Such a resource may be useful for prebiotic chemists to understand the range of conditions in each reaction environment, or to select the medium most applicable for their targeted reaction of interest for exploratory studies. [ABSTRACT FROM AUTHOR]

Volatile emissions from 22 bryophyte species from Peninsular Malaysia were collected using a dynamic headspace technique and analyzed by gas chromatography–mass spectrometry (GC-MS). Thirty organic compounds (VOCs) from eight different groups were detected in bryophytes from the montane forest in Cameron Highlands and the lowland dipterocarp forest in Lata Belatan. The headspace of bryophytes in Cameron Highlands was dominated by tetradecane, 2-ethyl-1-hexanol, decanal, pentanoic acid, 2,2,4-trimethyl-3-carboxyisopropyl, isobutyl ester, D-limonene and naphthalene. On the contrary, in the bryophyte headspace of Lata Belatan, naphthalene and tetradecane were dominant compounds. The elevational pattern detected in VOC composition of bryophytes appears to be an evolutionary feature at the family level that needs verification at other sites. The results also confirmed that the VOC composition of bryophytes is species-specific. The roles of VOCs in bryophytes are presented, including plant–plant communication and plant–insect interaction and as an additional taxonomic character in chemotaxonomy. [ABSTRACT FROM AUTHOR]

The homochirality of life remains one of the most enigmatic issues in the study of the origin of life. A proposed mechanism for symmetry breaking involves irradiation by circularly polarized light (CPL). To investigate the photoreaction of amino acids under CPL irradiation, a vacuum ultraviolet (VUV) CPL irradiation system was developed at the synchrotron light source UVSOR-III. Hydrogen Lyman-α CPL (121.6 nm) is considered a potential asymmetric source in space. Therefore, racemic alanine film samples were irradiated with Lyman-α CPL to explore the photoreaction of biomolecules. Circular dichroism (CD) spectra measurements revealed that irradiation with right- (left-) handed CPL induced a positive (negative) anisotropy factor g in the wavelength range of 180-240 nm. However, the spectra differed from those of enantiopure alanine, exhibiting broad wavelength ranges and no sign change. Liquid chromatography-mass spectrometry (LC-MS) measurements indicate formation of larger molecules, such as oligomeric alanine adducts or modified oligomers after the Lyman-α CPL irradiation. Additionally, CPL irradiation considerably changes the microstructure of the alanine film surface, leading to the formation of circular network aggregates on the scale of 100 nm. The morphology changes in the alanine film and/or the formation of the larger molecules could be possible causes of the modified anisotropy factor spectra compared to those of enantiopure alanine. These findings highlight the need for further research on the photoreaction of biomolecules in solid states under VUV CPL irradiation, particularly in the photoionization energy range, to validate the cosmic scenario of homochirality., (© 2024 The Author(s). Chirality published by Wiley Periodicals LLC.)