This article is part of the supplement: Second Congress of Italian Evolutionary Biologists (First Congress of the Italian Society for Evolutionary Biology)
Montmorillonite protection of an UV-irradiated hairpin ribozyme: evolution of the RNA world in a mineral environment
1 Department of Animal Biology and Genetics, University of Florence, via Romana 17, 50125 – Florence, Italy
2 Institut Jacques Monod, Laboratoire de Biochimie de l'Evolution et Adaptabilité Moléculaire, Université Paris VI, Tour 43, 2 place Jussieu, 75251 Paris Cedex 05, France
BMC Evolutionary Biology 2007, 7(Suppl 2):S2 doi:10.1186/1471-2148-7-S2-S2Published: 16 August 2007
The hypothesis of an RNA-based origin of life, known as the "RNA world", is strongly affected by the hostile environmental conditions probably present in the early Earth. In particular, strong UV and X-ray radiations could have been a major obstacle to the formation and evolution of the first biomolecules. In 1951, J. D. Bernal first proposed that clay minerals could have served as the sites of accumulation and protection from degradation of the first biopolymers, providing the right physical setting for the evolution of more complex systems. Numerous subsequent experimental studies have reinforced this hypothesis.
The ability of the possibly widespread prebiotic, clay mineral montmorillonite to protect the catalytic RNA molecule ADHR1 (Adenine Dependent Hairpin Ribozyme 1) from UV-induced damages was experimentally checked. In particular, the self-cleavage reaction of the ribozyme was evaluated after UV-irradiation of the molecule in the absence or presence of clay particles. Results obtained showed a three-fold retention of the self-cleavage activity of the montmorillonite-protected molecule, with respect to the same reaction performed by the ribozyme irradiated in the absence of the clay.
These results provide a suggestion with which RNA, or RNA-like molecules, could have overcame the problem of protection from UV irradiation in the RNA world era, and suggest that a clay-rich environment could have favoured not only the formation of first genetic molecules, but also their evolution towards increasingly complex molecular organization.