Luis Aragon

..Therefore, these results strongly suggest that normal yeast cells do not contain a DNA replication-completion checkpoint...

..In this issue of Molecular Cell, Farcas et al. (2011) demonstrate that intertwining between sister chromatids at metaphase is much more significant than previously thought and, remarkably, show that it depends on cohesin...

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..In this review we summarize our present understanding of this enigmatic protein complex...

..We propose that the completion of replication is not under the surveillance of known checkpoints...

..We conclude that post-replicative DNA repair involves cohesin dissociation by separase to promote accessibility to repair factors during the coordinated cellular response to restore DNA integrity...

..Our study also suggests a key role of sumoylation for nucleolar dynamics, perhaps in the compartmentalization of nuclear activities...

..Our data reveal the implication of yeast condensin in the arrangement of rDNA repeats into a heterochromatic-like structure that is important for the correct delineation of silencing domains in the nucleus...

..We conclude that budding yeast, like most eukaryotes, inhibit Pol I transcription before segregation as a prerequisite for chromosome condensation and faithful genome separation...

..At the molecular level, cohesion establishment involves two defined events, a chromatin binding step and a chromatid entrapment event driven by posttranslational modifications on cohesin subunits...

..These results point towards a role for the Smc5-Smc6 complex in preventing the formation of sister chromatid junctions, thereby ensuring the correct partitioning of chromosomes during anaphase...

..Here, we present results further supporting the importance of Smc5-Smc6 in maintaining the integrity of the repetitive ribosomal DNA (rDNA) locus, the largest repetitive region of the budding yeast genome...

..Finally, telomere segregation defects in cdc14 mutants(4) correlate with the presence of subtelomeric Y' elements and can be rescued by transcriptional inhibition of RNA polymerase II...

..Our findings show that the Smc5-Smc6 complex is essential for genome stability as it promotes repair of DSBs by error-free sister-chromatid recombination (SCR), thereby suppressing inappropriate non-sister recombination events...

..In addition, our study uncovers an unexpected role for the replication barrier protein Fob1 in rDNA segregation that is independent of Cdc14. These findings demonstrate that highly transcribed loci can cause chromosome nondisjunction...

..Recruitment by CTCF suggests a rationale for noncanonical cohesin functions and, because CTCF binding is sensitive to DNA methylation, allows cohesin positioning to integrate DNA sequence and epigenetic state...

..We conclude that stalled RNAP-II plays an active role in the cis-organisation of ribosomal repeats providing domains of polymerase specificity in the nucleolar transcription environment...

..These results demonstrate that chromosome resolution is not simply a consequence of compacting chromosome arms and that overall rDNA compaction is necessary to mediate the segregation of the long arm of chromosome XII...

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..Future studies will be targeted towards unravelling the nature of the additional segregation requirements for repetitive regions and the specifics of its cell cycle control...

..Inactivation of FEAR delays nucleolar segregation until late anaphase, demonstrating that one function of the FEAR network is to promote segregation of repetitive nucleolar chromatin during mid-anaphase...