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Open Access Research article

A stochastic model of the emergence of autocatalytic cycles

Alessandro Filisetti1*, Alex Graudenzi1, Roberto Serra12, Marco Villani12, Davide De Lucrezia1, Rudolf M Füchslin13, Stuart A Kauffman4, Norman Packard15 and Irene Poli16

Author Affiliations

1 European Centre for Living Technology, S.Marco 2940, 30124, Venice, Italy

2 Department Communication and Economics, University of Modena and Reggio Emilia, Via Allegri 9, 42100 Reggio Emilia, Italy

3 Artificial Intelligence Lab Univ. Zürich, Andreasstr. 15, CH-8050 Zürich, Switzerland

4 Departments of Biochemistry and Mathematics, University of Vermont, Burlington, VT 05405, USA

5 ProtoLife Inc, 57 Post St. Suite 513, San Francisco, CA 94104, USA

6 Department of statistics, University Ca'Foscari of Venice, 30121 Venice, Italy

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Journal of Systems Chemistry 2011, 2:2  doi:10.1186/1759-2208-2-2

Published: 22 June 2011

Abstract

Autocatalytic cycles are rather common in biological systems and they might have played a major role in the transition from non-living to living systems. Several theoretical models have been proposed to address the experimentalists during the investigation of this issue and most of them describe a phase transition depending upon the level of heterogeneity of the chemical soup. Nevertheless, it is well known that reproducing the emergence of autocatalytic sets in wet laboratories is a hard task. Understanding the rationale at the basis of such a mismatch between theoretical predictions and experimental observations is therefore of fundamental importance.

We here introduce a novel stochastic model of catalytic reaction networks, in order to investigate the emergence of autocatalytic cycles, sensibly considering the importance of noise, of small-number effects and the possible growth of the number of different elements in the system.

Furthermore, the introduction of a temporal threshold that defines how long a specific reaction is kept in the reaction graph allows to univocally define cycles also within an asynchronous framework.

The foremost analyses have been focused on the study of the variation of the composition of the incoming flux. It was possible to show that the activity of the system is enhanced, with particular regard to the emergence of autocatalytic sets, if a larger number of different elements is present in the incoming flux, while the specific length of the species seems to entail minor effects on the overall dynamics.