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Science 2013 Aug 23;3416148:893-6. doi: 10.1126/science.1241530.
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Titration of four replication factors is essential for the Xenopus laevis midblastula transition.

Collart C , Allen GE , Bradshaw CR , Smith JC , Zegerman P .

The rapid, reductive early divisions of many metazoan embryos are followed by the midblastula transition (MBT), during which the cell cycle elongates and zygotic transcription begins. It has been proposed that the increasing nuclear to cytoplasmic (N/C) ratio is critical for controlling the events of the MBT. We show that four DNA replication factors--Cut5, RecQ4, Treslin, and Drf1--are limiting for replication initiation at increasing N/C ratios in vitro and in vivo in Xenopus laevis. The levels of these factors regulate multiple events of the MBT, including the slowing of the cell cycle, the onset of zygotic transcription, and the developmental activation of the kinase Chk1. This work provides a mechanism for how the N/C ratio controls the MBT and shows that the regulation of replication initiation is fundamental for normal embryogenesis.

PubMed ID: 23907533
PMC ID: PMC3898016
Article link: Science
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: ccdc6 cdc6 chek1 dbf4b diaph1 recql4 ticrr topbp1
Morpholinos: cdc6 MO1 cdc6 MO2 dbf4b MO1 recql4 MO1 ticrr MO1

References [+] :
Blumenthal, The units of DNA replication in Drosophila melanogaster chromosomes. 1974, Pubmed