Studies on precellular evolution: the encapsulation of polyribonucleotides by liposomes

Area of Science:

• Biochemistry
• Origin of Life Studies
• Lipid Bilayer Systems

Background:

• Liposomes, lipid vesicles with internal aqueous compartments, are proposed as models for precellular systems.
• The early Earth's Archean environment may have featured non-enzymatic lipid self-assembly.
• RNA is hypothesized as the primary genetic material preceding DNA.

Purpose of the Study:

• To investigate the encapsulation of polyribonucleotides within liposomes.
• To assess liposome formation and polyribonucleotide entrapment efficiency.
• To examine the influence of prebiotic chemicals on encapsulation.

Main Methods:

• Liposomes were prepared using dipalmitoyl phosphatidylcholine and egg yolk phosphatidylcholine (with cholesterol).
• The reverse phase evaporation method was employed under anoxic conditions.
• Encapsulation efficiency was quantified for polyribonucleotides, with and without urea, cyanamide, Zn++, and Pb++.

Main Results:

• Approximately 50% of lipids successfully formed liposomes.
• Up to 5% of available polyribonucleotides were entrapped within the liposomes.
• Prebiotic condensing agents and metal cations were tested for their effect on encapsulation.

Conclusions:

• Liposomes can effectively encapsulate polyribonucleotides, a key step in RNA world models.
• The formation and entrapment efficiencies are significant for prebiotic chemistry.
• These findings support the role of liposomes in the origin of cellular life and genetic material.