[The democratic side of science-fiction]

Suspicion towards technological advances has progressively grown during the xx(th) century. However, in the XXI(st) century, reading the NBIC (nanotechnology, biotechnology, information technology and cognitive science) report of the National Science Foundation, we can note that science has caught up with science fiction. These changes in public mentality on one side and in scientific capacities on the other argue for an evolution of the debate on sciences. The recent example of the national debate on nanotechnology in France has clearly shown that the public is no longer waiting for additional sources of scientific knowledge but rather waiting for the recognition of its authority to participate in the definition of the national R&D priority and associated scientific strategies. This is all the more legitimate that these strategies will have profound impact on the future of our societies and therefore cannot be decided only by scientists. Hence, it is crucial to identify innovative tools promoting debate on sciences and their technological spin-off. Here, we contend that science fiction has major assets that could face this challenge and facilitate the dialogue between sciences and society.

[Circadian rhythms and systems biology]

Cellular rhythms represent a field of choice for studies in system biology. The examples of circadian rhythms and of the cell cycle show how the experimental and modeling approaches contribute to clarify the conditions in which periodic behavior spontaneously arises in regulatory networks at the cellular level. Circadian rhythms originate from intertwined positive and negative feedback loops controlling the expression of several clock genes. Models can be used to address the dynamical bases of physiological disorders related to dysfunctions of the mammalian circadian clock. The cell cycle is driven by a network of cyclin-dependent kinases (Cdks). Modeled in the form of four modules coupled through multiple regulatory interactions, the Cdk network operates in an oscillatory manner in the presence of sufficient amounts of growth factor. For circadian rhythms and the cell cycle, as for other recently observed cellular rhythms, periodic behavior represents an emergent property of biological systems related to their regulatory structure.