34 research outputs found
Non-coding telomeric and subtelomeric transcripts are differentially regulated by telomeric and heterochromatin assembly factors in fission yeast
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The Meiotic Chromosomal Bouquet: SUN Collects Flowers
No full textIn the early stages of meiosis, all the telomeres in the cell attach to the nuclear envelope and gather near the centrosome. This polarized chromosomal array is known as the bouquet, as the clustered telomeres resemble the gathered stems of a floral arrangement. In this issue of Cell, Chikashige et al. (2006) provide intriguing clues about the molecular details underlying this conserved meiotic event
Closed Mitosis: A Timely Move before Separation
No full textSummaryFaithful chromosome segregation entails long-range chromosome movement into newly dividing cells. A recent study implicates CDK1 function in releasing mitotic telomeres from the nuclear envelope, thereby liberating chromosomes for mitotic segregation
Stretching, scrambling, piercing and entangling: Challenges for telomeres in mitotic and meiotic chromosome segregation
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Telomeric Strategies: Means to an End
No full text What really defines a telomere? Telomere literally is an amalgamation of the Greek words “telos,” meaning end, and “mer,” meaning part. In practice, it refers to the extremities of linear chromosomes. The defining functions of chromosome extremities can be summarized in two main categories. First, chromosome ends trick the cell into not identifying them as damage-induced double-strand DNA breaks (DSBs). An internal DSB immediately triggers cell-cycle arrest and is repaired to ensure that genome integrity remains undisturbed. Chromosome ends disguise themselves using assorted strategies, tailored to evade specific cellular responses. The second defining function of chromosome extremities involves self-preservation. Due to the inherent limitations of the canonical replication machinery, chromosomes gradually lose terminal DNA with successive rounds of replication. Telomeres have evolved tactics to circumvent this loss and to preserve themselves. This review focuses on highlights of telomeric strategies surrounding these two primary tasks, and finishes by discussing evidence that the full telomeric functional repertoire has yet to be defined. </jats:p
The Telomere Bouquet Controls the Meiotic Spindle
No full textSummaryBouquet formation, in which telomeres gather to a small region of the nuclear membrane in early meiosis, has been observed in diverse eukaryotes, but the function of the bouquet has remained a mystery. Here, we demonstrate that the telomere bouquet plays a crucial role in controlling the behavior of the fission yeast microtubule-organizing center (known as the spindle pole body or SPB) and the meiotic spindle. Using mutations that specifically disrupt the bouquet, we analyze chromosome, SPB, and spindle dynamics throughout meiosis. If the bouquet fails to form, the SPB becomes fragmented at meiosis I, leading to monopolar, multiple, and mislocalized spindles. Correct SPB and spindle behavior require not only the SPB recruitment of telomere proteins but also that the proteins are properly bound to telomeric DNA. This discovery illuminates an unanticipated level of communication between chromosomes and the spindle apparatus that may be widely conserved among eukaryotes
Author response: Distinct ‘safe zones’ at the nuclear envelope ensure robust replication of heterochromatic chromosome regions
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