Eukaryotic DNA replication is a topographically ordered process

This paper describes the relationship between the BrdUrd replicating pattern of a cell and its localization within the S phase by means of topographical features and DNA content measurement. The present study follows an objective ranking of the BrdUrd patterns obtained from a spectral analysis of the BrdUrd images. The pattern ranking was consistent with the DNA content increase throughout the S phase. Five texture groups were arbitrarily set up for the purpose of multivariate analysis. Nine topographical parameters were computed for each BrdUrd-labelled nucleus. The descriptive quality of these parameters was assessed by means of factorial discriminant analysis. These parameters made it possible to characterize objectively the known pattern distributions of replication sites qualitatively described in the literature.