Abstract EANA2024-45

Primordial membranes are thought to have been majorly composed of single chain amphiphiles (SCA). The prebiotic soup was presumably a host for a variety of such membrane-forming components delivered via exogenous meteoritic delivery or endogenous prebiotic synthesis on early Earth. The SCAs are typically of different acyl chain lengths and polar head groups, potentially resulting in an enormous heterogeneity in the prebiotic soup. These molecules are also known to spontaneously self-assemble into vesicles, resulting in ‘protocells’. The propensity for protocell formation and the variety in membrane forming components is thought to have resulted in spontaneous generation of characteristically distinct ‘protocellular species’ in a putative early-Earth ‘niche’. In this backdrop, we explored a multispecies approach of studying physicochemically distinct protocell populations to test whether their interaction dynamics could facilitate ‘emergent’ properties at a systems level. We also investigated if such a ‘niche’ of coexisting populations could undergo membrane evolution, especially in terms of its biophysical property and overall sustainability. We used a SCA-based model system to generate a library of four distinct ‘protocell species’ to characterize the aforementioned propositions. Our studies show that the implications are multipronged and the outcomes vary depending on the membrane properties of the different protocell ‘species’ interacting in the system. We demonstrate how one of the protocell populations acts as the ‘predator’ while the other acts as a ‘prey’ in a two-candidate multispecies model. The predator protocell species showed growth with distinct morphology changes. Further, we also show that in this scenario, the ‘fitter’ membrane achieves more robustness due to this process. Interestingly, the ‘prey’ population also accrued emergent properties without getting completely outcompeted or diminished. We observed molecular crowding in the lumen of the prey that potentially resulted in shrink-wrapping of the encapsulant molecules. These studies were extrapolated to study a three-candidate population and found that the outcomes are even more complex. 

 

Further, to gain a “realistic” understanding of these laboratory investigations, we also investigated some of the aforementioned aspects using hot-spring samples from analogue environments in Ladakh, India. This region is considered an early Earth/Mars analogue site and comprises of various pertinent geological features hosting extreme environments including permafrost, hot-spring systems, hypersaline lakes etc. Water samples from Puga, a geothermal hot spring, and Tso-Moriri (a high-altitude fresh-water lake), were used to recreate a “realistic” early Earth ‘niche’ that comprised of varying ionic species while having a pH that is mostly similar to lab-simulated experimental conditions. In all, ourfindings show how niche parameters would have impinged on protocell membrane evolution in coexisting populations, wherein the ‘fitter’ membrane systems could have a selective advantage due to benefitting more. Also, we demonstrate a scenario of coexisting protocell populations which seems mutually benefit from their interactions, resulting in emergent functions in the that would have had interesting ramifications for the origins of life.