Emergence of self-reproduction in cooperative chemical evolution of prebiological molecules

Semantic parsing of the life process by quantum biology

A fact that an ever-increasingly number of research attention has focused on quantum biology demonstrates that it is, by no means, new to works in physic and mathematics, but to molecular biologists, geneticists, and biochemists. This is owing to that quantum biology serves as a distinctive discipline, by using quantum theory to study life sciences in combination with physics, mechanics, mathematics, statistics, and modern biology. Notably, quantum mechanics and its fundamental principles have been employed to clarify complex biological processes and molecular homeostasis within the organic life. Consequently, using the principles of quantum mechanics to study dynamic changes and energy transfer of molecules at the quantum level in biology has been accepted as an unusually distinguishable way to a better explanation of many phenomena in life. It is plausible that a clear conceptual quantum theoretical event is also considered to generally occur for short-term picoseconds or femtoseconds on microscopic nano- and subnanometer scales in biology and biosciences. For instance, photosynthesis, enzyme -catalyzed reactions, magnetic perception, the capture of smell and vision, DNA fragmentation, cellular breathing, mitochondrial processing, as well as brain thinking and consciousness, are all manifested within quantum superposition, quantum coherence, quantum entanglement, quantum tunneling, and other effects. In this mini-review, we describe the recent progress in quantum biology, with a promising direction for further insights into this field.

Chance and Necessity in the Evolution of Matter to Life: A Comprehensive Hypothesis

Specialists in several branches of life sciences are trying to solve, piece by piece, the immensely complex puzzle of the origin of life. Some parts of the puzzle seem to appear with a rather high degree of clarity, while others remain totally obscure. We cannot be sure that life emerged only on our Earth, but we believe that the presence of large amounts of water in its liquid state is absolutely essential for the emergence and evolution of living matter. We can also assume that the latter exploits everywhere the same light elements, mainly C, H, O, N, S, and P, and somehow manipulates the same simple monomeric and polymeric organic compounds, such as alpha-amino acids, carbohydrates, nucleic bases, and surface-active carboxylic acids. The author contributes to the field by stating that all fundamental particles of our matter are “homochiral” and predominantly produce in an absolute asymmetric synthesis amino acids of L-configuration and carbohydrates of D-series. Another important point is that free atmospheric oxygen mainly stems from the photolysis of water molecules by cosmic irradiation and is not necessarily bound to living organisms on the planet.

A Peptide-Nucleic Acid Replicator Origin for Life

Evolution requires self-replication. But, what was the very first self-replicator directly ancestral to all life? The currently favoured RNA World theory assigns this role to RNA alone but suffers from a number of seemingly intractable problems. Instead, we suggest that the self-replicator consisted of both peptides and nucleic acid strands. Such a nucleopeptide replicator is more feasible both in the light of the replication machinery currently found in cells and the complexity of the evolutionary path required to reach them. Recent theoretical and mathematical work supports this idea and provide a blueprint for future investigations.

Prebiotic Peptides: Molecular Hubs in the Origin of Life

The fundamental roles that peptides and proteins play in today's biology makes it almost indisputable that peptides were key players in the origin of life. Insofar as it is appropriate to extrapolate back from extant biology to the prebiotic world, one must acknowledge the critical importance that interconnected molecular networks, likely with peptides as key components, would have played in life's origin. In this review, we summarize chemical processes involving peptides that could have contributed to early chemical evolution, with an emphasis on molecular interactions between peptides and other classes of organic molecules. We first summarize mechanisms by which amino acids and similar building blocks could have been produced and elaborated into proto-peptides. Next, non-covalent interactions of peptides with other peptides as well as with nucleic acids, lipids, carbohydrates, metal ions, and aromatic molecules are discussed in relation to the possible roles of such interactions in chemical evolution of structure and function. Finally, we describe research involving structural alternatives to peptides and covalent adducts between amino acids/peptides and other classes of molecules. We propose that ample future breakthroughs in origin-of-life chemistry will stem from investigations of interconnected chemical systems in which synergistic interactions between different classes of molecules emerge.

Reciprocal Nucleopeptides as the Ancestral Darwinian Self-Replicator

Even the simplest organisms are too complex to have spontaneously arisen fully formed, yet precursors to first life must have emerged ab initio from their environment. A watershed event was the appearance of the first entity capable of evolution: the Initial Darwinian Ancestor. Here, we suggest that nucleopeptide reciprocal replicators could have carried out this important role and contend that this is the simplest way to explain extant replication systems in a mathematically consistent way. We propose short nucleic acid templates on which amino-acylated adapters assembled. Spatial localization drives peptide ligation from activated precursors to generate phosphodiester-bond-catalytic peptides. Comprising autocatalytic protein and nucleic acid sequences, this dynamical system links and unifies several previous hypotheses and provides a plausible model for the emergence of DNA and the operational code.

Universal sequence replication, reversible polymerization and early functional biopolymers: a model for the initiation of prebiotic sequence evolution

Many models for the origin of life have focused on understanding how evolution can drive the refinement of a preexisting enzyme, such as the evolution of efficient replicase activity. Here we present a model for what was, arguably, an even earlier stage of chemical evolution, when polymer sequence diversity was generated and sustained before, and during, the onset of functional selection. The model includes regular environmental cycles (e.g. hydration-dehydration cycles) that drive polymers between times of replication and functional activity, which coincide with times of different monomer and polymer diffusivity. Template-directed replication of informational polymers, which takes place during the dehydration stage of each cycle, is considered to be sequence-independent. New sequences are generated by spontaneous polymer formation, and all sequences compete for a finite monomer resource that is recycled via reversible polymerization. Kinetic Monte Carlo simulations demonstrate that this proposed prebiotic scenario provides a robust mechanism for the exploration of sequence space. Introduction of a polymer sequence with monomer synthetase activity illustrates that functional sequences can become established in a preexisting pool of otherwise non-functional sequences. Functional selection does not dominate system dynamics and sequence diversity remains high, permitting the emergence and spread of more than one functional sequence. It is also observed that polymers spontaneously form clusters in simulations where polymers diffuse more slowly than monomers, a feature that is reminiscent of a previous proposal that the earliest stages of life could have been defined by the collective evolution of a system-wide cooperation of polymer aggregates. Overall, the results presented demonstrate the merits of considering plausible prebiotic polymer chemistries and environments that would have allowed for the rapid turnover of monomer resources and for regularly varying monomer/polymer diffusivities.

Primal eukaryogenesis: on the communal nature of precellular States, ancestral to modern life

This problem-oriented, exploratory and hypothesis-driven discourse toward the unknown combines several basic tenets: (i) a photo-active metal sulfide scenario of primal biogenesis in the porespace of shallow sedimentary flats, in contrast to hot deep-sea hydrothermal vent conditions; (ii) an inherently complex communal system at the common root of present life forms; (iii) a high degree of internal compartmentalization at this communal root, progressively resembling coenocytic (syncytial) super-cells; (iv) a direct connection from such communal super-cells to proto-eukaryotic macro-cell organization; and (v) multiple rounds of micro-cellular escape with streamlined reductive evolution-leading to the major prokaryotic cell lines, as well as to megaviruses and other viral lineages. Hopefully, such nontraditional concepts and approaches will contribute to coherent and plausible views about the origins and early life on Earth. In particular, the coevolutionary emergence from a communal system at the common root can most naturally explain the vast discrepancy in subcellular organization between modern eukaryotes on the one hand and both archaea and bacteria on the other.