Heritable, mutable, and selectable spatial patterns from bistable chemical reaction networks in weakly-coupled reactor arrays

Abstract

The origins of genetic information processing remain a mystery in prebiotic chemistry research. Genetic systems encode information as digital sequences of nucleotide residues and require multiple interdependent and complex machineries that were likely to have been established late in the prebiotic evolutionary process. Candidate predecessor systems are potentially insightful for examining how genetic systems could have been scaffolded by alternatives that were simpler, yet capable of performing comparable functions. Some researchers have proposed that relative concentrations of simple chemical species (i.e., chemical compositions) could encode heritable information in an analog manner. While conceptually plausible, it is also difficult to explain how most forms of analog inheritance (which can be highly sensitive to interference) could underpin emergent characteristics that are necessary for adaptive evolution afforded by high-fidelity, polymer-based digital inheritance. Here, by simulating bistable reaction systems with two simple autocatalytic cycles in two-dimensional lattices of connected flow reactors, we show that without linear polymers, it is still possible to encode spatial configurations of discrete states of chemical compositions that are heritable and mutable. Different configurations can have differing likelihoods of propagating to new reactors or recovering from perturbations, which means that they can respond to at least some types of selective environments or conditions. Taken together, these spatial configurations are heritable, mutable, and selectable (HMS). They are similar to analog inheritance because they depend on chemical compositions, and they are similar to digital inheritance because they consist of spatially distributed, discretized units. Although such discrete HMS spatial configurations are far less heritable, more mutable, and less selectable than nucleotide-sequence-based digital inheritance, they represent a possible bridge between analog and digital inheritance in complex chemical systems.

Assessment of Stoichiometric Autocatalysis across Element Groups

“…The comproportionation or auxiliary process of a CompAC may consume an autocatalyst of another CompAC as food, synonymizing these CompACs to a predator–prey relationship 22 , 23 ( Figure 2 d,e). Bistability and the priority effect are also possible if autocatalysts of different CompACs dimerize to form a new chemical species 104 ( Figure 2 f).…”

An assessment of stoichiometric autocatalysis across element groups

“…Bistability and the priority effect are also possible, if autocatalysts of different CompACs dimerize to form a new chemical species (Fig. 2F) (Peng et al, 2023).…”

“…Attributes typically associated with living organisms such as multistability, competition, mutualism, predation, the priority effect, gradual complexification, and adaptive responses to selection, can readily emerge from interacting abiotic autocatalytic reaction systems that do not involve macromolecules (Cornish-Bowden and Cá rdenas, 2020;Gá nti, 2003;Hunding et al, 2006;Peng et al, 2023Peng et al, , 2022Peng et al, , 2020. The Belousov-Zhabotinsky reaction is a classic example of an autocatalytic reaction network generated from the aqueous combination of a few simple organic and inorganic reagents that yields bistability and chemical oscillations (Zhabotinsky, 2007).…”

“…No reason has been unequivocally enunciated, however, to ignore wholesale other elements and inorganic compounds that might have scaffolded life's origins terrestrially or elsewhere in the cosmos (Blokhuis, 2019). For example, complex functions, though seemingly requiring diverse and highly evolved catalytic polymers, may be partiallyalbeit imperfectlyundertaken by inorganic catalysts (e.g., metal ions) and interactions between simple autocatalytic cycles (Cornish-Bowden and Cá rdenas, 2020;Gá nti, 2003;Hunding et al, 2006;Kahana and Lancet, 2021;Muchowska et al, 2020Muchowska et al, , 2017Peng et al, 2023Peng et al, , 2022Peng et al, , 2020Plum and Baum, 2022). It is also possible that other pathways to alternative, non-Terran examples of life-like systems can arise under laboratory or exoplanetary/astrochemical conditions that largely deviate from terrestrial environments (Kawai et al, 2013;McKay, 1998;Stevenson et al, 2015).…”