Possible involvement of a cell cycle control system dependent on nuclear activities in establishment of the cell division interval in early Xenopus embryos
T. Gotoh et al., Possible involvement of a cell cycle control system dependent on nuclear activities in establishment of the cell division interval in early Xenopus embryos, ZOOL SCI, 15(6), 1998, pp. 913-922
In early Xenopus embryos, continuous exposure of embryos to aphidicolin and
inactivation of the nucleus by ultraviolet-irradiation induce prolongation
of the cell division interval. The extent of prolongation of the cell divi
sion interval appears to depend on how heavily DNA replication is suppresse
d by the treatments. Embryos showing significantly prolonged cell division
intervals tend to fail normal cell divisions, often forming abortive furrow
s. There appears to be a critical point for the extent of prolongation of t
he cell division interval at 30% that divides the success and failure of no
rmal cell division. This percentage, 30%, coincides with that for the prolo
ngation of the interval of oscillatory activities seen in enucleated eggs.
The presence of an intact nucleus that can undergo DNA replication rescues
normal cell divisions with normal intervals and a normal furrow. Histologic
ally, the nucleus in embryos showing more than 30% prolongation of cell div
ision intervals appears to fail DNA replication and remain unduplicated wit
h a round morphology like the interphase nucleus. A number of unduplicated
asters lacking chromosomes are found in these embryos. We conclude from the
se results that early Xenopus embryos, like late embryos, have a cell cycle
control system that is affected by DNA replication and is involved in esta
blishing the cell division interval.