DNA-replication checkpoint control at the Drosophila midblastula transition
TLDR
This article showed that mutations in the grapes (grp) checkpoint 1 kinase homologue in Drosophila block the morphological and biochemical changes that accompany the midblastula transition, leading to a continuation of the maternal cell-cycle programme, and disrupt DNA-replication checkpoint control of cell cycle progression.Abstract:
Embryogenesis is typically initiated by a series of rapid mitotic divisions that are under maternal genetic control. The switch to zygotic control of embryogenesis at the midblastula transition is accompanied by significant increases in cell-cycle length and gene transcription, and changes in embryo morphology. Here we show that mutations in the grapes (grp) checkpoint 1 kinase homologue in Drosophila block the morphological and biochemical changes that accompany the midblastula transition, lead to a continuation of the maternal cell-cycle programme, and disrupt DNA-replication checkpoint control of cell-cycle progression. The timing of the midblastula transition is controlled by the ratio of nuclei to cytoplasm (the nucleocytoplasmic ratio), suggesting that this developmental transition is triggered by titration of a maternal factor by the increasing mass of nuclear material that accumulates during the rapid embryonic mitoses. Our observations support a model for cell-cycle control at the midblastula transition in which titration of a maternal component of the DNA-replication machinery slows DNA synthesis and induces a checkpoint-dependent delay in cell-cycle progression. This delay may allow both completion of S phase and transcription of genes that initiate the switch to zygotic control of embryogenesis.read more
Citations
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Egg timers: how is developmental time measured in the early vertebrate embryo?
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Timing the Drosophila Mid-Blastula Transition: A Cell Cycle-Centered View
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References
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A non-radioactive in situ hybridization method for the localization of specific RNAs in Drosophila embryos reveals translational control of the segmentation gene hunchback.
Diethard Tautz,Christine Pfeifle +1 more
TL;DR: A non-radioactive in situ hybridization technique for the localization of RNA in whole mount Drosophila embryos and revealed translational control of the maternally derived hb mRNA, which was difficult to detect by conventional techniques.
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Cell Cycle Checkpoints: Preventing an Identity Crisis
TL;DR: Signal transduction pathways that transmit checkpoint signals in response to DNA damage, replication blocks, and spindle damage are revealed, underscoring the conservation of cell cycle regulatory machinery.
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A major developmental transition in early xenopus embryos: I. characterization and timing of cellular changes at the midblastula stage
TL;DR: The Xenopus embryo undergoes 12 rapid synchronous cleavages followed by a period of slower asynchronous divisions more typical of somatic cells, termed the midblastula transition (MBT), which shows that at the MBT the blastomeres become motile and transcriptionally active for the first time.
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Studies of nuclear and cytoplasmic behaviour during the five mitotic cycles that precede gastrulation in Drosophila embryogenesis
V.E. Foe,B.M. Alberts +1 more
TL;DR: Using differential interference contrast optics, combined with cinematography, the morphological changes that the living, syncytial embryo undergoes from stage 10 through 14 of Drosophila embryogenesis, that is just prior to and during formation of the cellular blastoderm are studied.