Article Abstract:
Schizosaccharomyces pombe forms an actin-based contractile ring prior to cell division. As mitosis proceeds, the ring contracts as the septum is formed at the site marked by the actin ring. The formation of the contractile ring is regulated by the genes cdc3, cdc4, cdc8, cdc12, cdc15 and rng2, whose regulation of expression produces large multinucleate cells that are not viable. Possible theories for the spatial positioning of the contractile ring include the role of mitotic spindle, the use of a previous division scar, or a cortical marker to determine the centric position of the cleavage plane.
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Article Abstract:
The p65(super cdc18) protein coded by the fission yeast gene cdc18 is responsible for the initiation of DNA replication. The protein regulates the onset of the S phase of the cell cycle. The cdc18 gene is transcriptionally activated by the cdc10/res1/res2 control at START in late G1. The level of p65(super cdc18) is highest in the transition from the G1 to the S phase. Overexpression of the cdc18 gene results in repeated rounds of DNA and protein synthesis without mitosis.
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Article Abstract:
An epigenetic mechanism was shown to regulate the efficiency of mating-type interconversion and the silencing of a marker gene inserted at the K-region. In addition, the generation and propagation of such epigenetic states were shown to be controlled by the clr1, clr2, clr3, clr4 and swi6 gene functions. Finally, epigenetic states were found to be highly stable. These states are inherited during mitosis and meiosis as Mendelian genetic markers.
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