A material‐based panspermia hypothesis: The potential of polymer gels and membraneless droplets

Abstract

The Panspermia hypothesis posits that either life's building blocks (molecular Panspermia) or life itself (organism‐based Panspermia) may have been interplanetarily transferred to facilitate the origins of life (OoL) on a given planet, complementing several current OoL frameworks. Although many spaceflight experiments were performed in the past to test for potential terrestrial organisms as Panspermia seeds, it is uncertain whether such organisms will likely “seed” a new planet even if they are able to survive spaceflight. Therefore, rather than using organisms, using abiotic chemicals as seeds has been proposed as part of the molecular Panspermia hypothesis. Here, as an extension of this hypothesis, we introduce and review the plausibility of a polymeric material‐based Panspermia seed (M‐BPS) as a theoretical concept, where the type of polymeric material that can function as a M‐BPS must be able to: (1) survive spaceflight and (2) “function”, i.e., contingently drive chemical evolution toward some form of abiogenesis once arriving on a foreign planet. We use polymeric gels as a model example of a potential M‐BPS. Polymeric gels that can be prebiotically synthesized on one planet (such as polyester gels) could be transferred to another planet via meteoritic transfer, where upon landing on a liquid bearing planet, can assemble into structures containing cellular‐like characteristics and functionalities. Such features presupposed that these gels can assemble into compartments through phase separation to accomplish relevant functions such as encapsulation of primitive metabolic, genetic and catalytic materials, exchange of these materials, motion, coalescence, and evolution. All of these functions can result in the gels' capability to alter local geochemical niches on other planets, thereby allowing chemical evolution to lead to OoL events.

The Effects of Dehydration Temperature and Monomer Chirality on Primitive Polyester Synthesis and Microdroplet Assembly

“…[19,22] Such droplets (which do not contain lipid-based membranes and can thus be considered "membraneless") can perform prebiotically relevant functions such as nucleic acid segregation [19] or recombination, [22] and have been proposed as primitive compartment models [22] or panspermia seeds. [23] This is partially due to their similarity in structure to modern membraneless organelles, which play diffusive, coalescence and wetting, pathological, and catalytic roles within cells, suggesting their longstanding importance to biology. [24][25][26] However, understanding of the scope of synthetic conditions which enable such prebiotic polyester and droplet formation is presently limited in scope, often using only the most experimentally expedient temperature conditions (e.g., 80 °C) [19,22] and starting materials (racemic 𝛼HA monomers).…”

“…[ 19,22 ] Such droplets (which do not contain lipid‐based membranes and can thus be considered “membraneless”) can perform prebiotically relevant functions such as nucleic acid segregation [ 19 ] or recombination, [ 22 ] and have been proposed as primitive compartment models [ 22 ] or panspermia seeds. [ 23 ] This is partially due to their similarity in structure to modern membraneless organelles, which play diffusive, coalescence and wetting, pathological, and catalytic roles within cells, suggesting their longstanding importance to biology. [ 24–26 ]…”

Recent progress in primitive polyester synthesis and membraneless microdroplet assembly

“…However, such panspermia seeds must survive the harsh conditions of space (including radiation, temperature fluctuation, microgravity, etc.) and also simultaneously protect the encapsulated chemicals from degradation [ 92 ]. Further studies characterizing the stability of polyester gels in extraterrestrial conditions, such as cosmic radiation or microgravity, are required.…”

“… Proposal for polyester gels to act as material-based Pansmermia seeds (M-BPS), and protect and transport compartmentalized analytes during extraterrestrial travel to a recipient planet. Reprinted with permission from [ 92 ], copyright John Wiley and Sons. …”

Small Amphiphile‐Based Coacervation

“…Moreover, life is suggested to develop from coacervates spontaneously formed by amphipathic molecules (e. g., lipids), amino acids and nucleotides [20–22] . Progress in the origin of life has evoked different hypothesis, in which coacervates and prebiotic polymeric gels were referred as possible origination of the prebiotic molecules [23,24] . In contrast to the extensive progress in the understanding of LLPS of macromolecules, attention in amphiphile‐based coacervation has lagged behind.…”