Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học quốc tế cung cấp cho các bạn kiến thức về ngành y đề tài: " A stochastic model for circadian rhythms from coupled ultradian oscillators | Theoretical Biology and Medical Modelling BioMed Central Research Open Access A stochastic model for circadian rhythms from coupled ultradian oscillators Roderick Edwards 1 Richard Gibson1 Reinhard Illner1 and Verner Paetkau2 Address Department of Mathematics and Statistics University of Victoria . Box 3045 STN CSC Victoria BC V8W 3P4 Canada and 2Department of Biochemistry and Microbiology University of Victoria . Box 3055 STN CSC Victoria BC V8W 3P6 Canada Email Roderick Edwards - edwards@ Richard Gibson - richieg@ Reinhard Illner - rillner@ Verner Paetkau - vhp@ Corresponding author Published 9 January 2007 Received 15 September 2006 Theoretical Biology and Medical Modelling 2007 4 1 doi 1742-4682-4-1 Accepted 9 January 2007 This article is available from http content 4 1 1 2007 Edwards et al licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License http licenses by which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. Abstract Background Circadian rhythms with varying components exist in organisms ranging from humans to cyanobacteria. A simple evolutionarily plausible mechanism for the origin of such a variety of circadian oscillators proposed in earlier work involves the non-disruptive coupling of pre-existing ultradian transcriptional-translational oscillators TTOs producing beats in individual cells. However like other TTO models of circadian rhythms it is important to establish that the inherent stochasticity of the protein binding and unbinding does not invalidate the finding of clear oscillations with circadian period. Results The TTOs of our model are described in two versions 1 a version in which the activation or inhibition of genes is regulated stochastically where the unoccupied or free time of the site under consideration
