DNA Replication Patterns in the Chromosomes of the Domestic Fowl

抄録

Terminal uptake of ³H-thymidine and autoradiography were employed to study the late replication pattern of chromosomes from three day old embryos of the domestic fowl, Gallus domesticus. In the male both Z chromosomes replicated synchronously while the W chromosome of the female replicated asynchronously relative to the Z chromosome. Contrary to previous studies, the microchromosomes appeared to replicate during the same time as the macrochromosomes. The data indicated that the pattern of replication was not necessarily the same for all cells and that the mitotic cycle differed in cells of various tissues. The inconsistencies in replication pattern and mitotic cycle are probably a reflection of differentiation in the embryo. The behavior of the microchromosomes indicates they are true chromosomes. Silver grains were distributed in a nonrandom fashion over interphase nuclei, indicating some degree of chromosome organization exists during the S period.