“We show how recurring environmental constraints on ancient earth, namely cycles of freezing and thawing, might have driven the dissemination of genetic material in populations of primitive protocells. In this work, confocal fluorescence microscopy at sub-zero temperatures was used to gain mechanistic insights into inter-protocellular communication based on cyclic freezing and melting of the aqueous environment. The cover design highlights the transient formation of membrane pores that enable content diffusion across protocell membranes…” This and more about the story behind the front cover can be found in the Research Article at 10.1002/syst.202300008.

Abstract

The front cover artwork is provided by the Schwille group from the Max Planck Institute of Biochemistry in Martinsried. The image shows the dissemination of genetic material in a population of primitive protocells during freeze-thaw induced periods of membrane permeability. Read the full text of the Research Article at 10.1002/syst.202300008.

The Front Cover illustrates the exchange of genetic material between model protocells through cycles of freezing and thawing. Freeze-thaw cycles as prebiotic environmental driver induce a transient increase in membrane permeability enabling the lateral transfer of genetic information in a population of primitive protocells. More information can be found in the Research Article by Benedikt Peter and Petra Schwille.

Freeze-thaw cycles serve as physicochemical driving force for the lateral exchange of enclosed material between giant lipid vesicles. It was demonstrated that this exchange relies on transient periods of membrane permeability leading to content diffusion across vesicle membranes. Moreover, we explored and quantified essential parameters affecting the lateral transfer efficiency.

Abstract

Modern cells rely on highly evolved protein networks to accomplish essential life functions, including the inheritance of information from parents to their offspring. In the absence of these sophisticated molecular machineries, alternatives were required for primitive protocells to proliferate and disseminate genetic material. Recurring environmental constraints on ancient earth, such as temperature cycles, are considered as prebiotically plausible driving forces capable of shuffling of protocellular contents, thereby boosting compositional complexity. Using confocal fluorescence microscopy, we show that temperature oscillations such as freezing-thawing (FT) cycles promote efficient content mixing between giant unilamellar vesicles (GUVs) as model protocells. We shed light on the underlying exchange mechanism and demonstrate that transient periods of destabilized membranes enable the diffusion of cargo molecules across vesicle membranes. Furthermore, we determine essential parameters, such as membrane composition, and quantify their impact on the lateral transfer efficiency. Our work outlines a simple scenario revolving around inter-protocellular communication environmentally driven by periodic freezing and melting of water.