News & Views |
Featured
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News |
Lights, camera, action for cells
Time-lapse films reveal the functions of human genes.
- Janelle Weaver
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Letter |
Sister chromosome pairing maintains heterozygosity in parthenogenetic lizards
The existence of all-female species of whiptail lizard, formed as a hybrid between sexual species, has been known since 1962; however, how the meiotic program is altered to produce diploid eggs while maintaining heterozygosity has remained unclear. Here it is shown in parthenogenetic species that meiosis initiates with twice the number of chromosomes compared to sexual species, and that pairing and recombination takes place between genetically identical sister chromosomes instead of between homologues.
- Aracely A. Lutes
- , William B. Neaves
- & Peter Baumann
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Research Highlights |
Stem cells: Uneven divide
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Letter |
The Dbf4–Cdc7 kinase promotes S phase by alleviating an inhibitory activity in Mcm4
Kinase regulatory pathways are used in eukaryotic DNA replication to facilitate coordination with other processes during cell division cycles and response to environmental cues. The Dbf4–Cdc7 kinase (DDK) is one of at least two cell-cycle-regulated protein kinase systems essential for initiation of DNA replication. DDK is now shown to relieve the inhibitory activity of the amino-terminal domain of the replicative helicase Mcm4, thus promoting S phase.
- Yi-Jun Sheu
- & Bruce Stillman