The chromosomal origin of replication as the basis for the spatio-temporal biology of bacteria

Spatial biology depends on the structural dynamics of the constituents of the cell. We propose that such dynamics during the cell cycle depend to a large extent on the origin of replication and its role in the trajectory of a replication hyperstructure. To explore this ori-Centric view, we adopt both historical and speculative approaches to the initiation of chromosome replication, focusing on Escherichia coli. We relate these approaches to the framework of concepts, results, and procedures within which science is structured; this framework can be considered a paradigm or a "thought style" that sometimes undergoes a major shift. We suggest that a paradigm shift is underway in the study of the cell cycle as shown by the increasing contribution of physical chemistry and, in particular, phase transitions.