Throughout my scientific career during and after my tenure at Ohio State University, I have promoted the concept of master origins of replication that are associated with tissue differentiation during embryonic development: see Studies on Eukaryotic DNA Superstructure (1988, page 221, pdf download). It is well known that origins of replication “disappear” as tissue differentiation begins. What has been less known is the level of organization associated with their disappearance. That is, until recently: (see links below).
Bottom line: As replication origins disappear, promoters of transcription appear and tissue development begins. This is not mere coincidence. Where do the origins “go” and where do the promoters “come from”? That, my fellow travelers, is the absolute crux of everything I have been saying throughout this blog and my Ph.D. career.