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Milks Kirstin J - - 2009
Eukaryotic cells ensure accurate chromosome segregation in mitosis by assembling a microtubule-binding site on each chromosome called the kinetochore that attaches to the mitotic spindle. The kinetochore is assembled specifically during mitosis on a specialized region of each chromosome called the centromere, which is constitutively bound by >15 centromere-specific proteins. ...
Santaguida Stefano - - 2009
Kinetochores are large protein assemblies built on chromosomal loci named centromeres. The main functions of kinetochores can be grouped under four modules. The first module, in the inner kinetochore, contributes a sturdy interface with centromeric chromatin. The second module, the outer kinetochore, contributes a microtubule-binding interface. The third module, the ...
Ng Tessie M - - 2009
Accurate chromosome segregation depends on sister kinetochores making bioriented attachments to microtubules from opposite poles. An essential regulator of biorientation is the Ipl1/Aurora B protein kinase that destabilizes improper microtubule-kinetochore attachments. To identify additional biorientation pathways, we performed a systematic genetic analysis between the ipl1-321 allele and all nonessential budding ...
Schittenhelm Ralf B - - 2009
The kinetochore is assembled during mitotic and meiotic divisions within the centromeric region of chromosomes. It is composed of more than eighty different proteins. Spc105 (also designated as Spc7, KNL-1 or Blinkin in different eukaryotes) is a comparatively large kinetochore protein, which can bind to the Mis12/MIND and Ndc80 complexes ...
Matos Irina - - 2009
The synchronous movement of chromosomes during anaphase ensures their correct inheritance in every cell division. This reflects the uniformity of spindle forces acting on chromosomes and their simultaneous entry into anaphase. Although anaphase onset is controlled by the spindle assembly checkpoint, it remains unknown how spindle forces are uniformly distributed ...
Yuan Kai - - 2009
Mitosis is an orchestration of dynamic interactions between spindle microtubules and chromosomes, which is mediated by protein structures that include the kinetochores, and other protein complexes present on chromosomes. PinX1 is a potent telomerase inhibitor in interphase; however, its function in mitosis is not well documented. Here we show that ...
Makrantoni Vasso - - 2009
Accurate chromosome segregation requires the capture of sister kinetochores by microtubules from opposite spindle poles prior to the initiation of anaphase, a state termed chromosome biorientation. In the budding yeast Saccharomyces cerevisiae, the conserved protein kinase Ipl1 (Aurora B in metazoans) is critical for ensuring correct chromosomal alignment. Ipl1 associates ...
Cai Shang S Indiana University, Bloomington, 47405, - - 2009
Proper chromosome congression (the process of aligning chromosomes on the spindle) contributes to accurate and faithful chromosome segregation. It is widely accepted that congression requires kinetochore fibres (K-fibres), microtubule bundles that extend from the kinetochores to spindle poles. Here, we demonstrate that chromosomes in human cells co-depleted of HSET (human ...
Wignall Sarah M SM Department of Developmental Biology, Stanford University School of Medicine, CA 94305, USA. - - 2009
Although centrosomes serve to organize microtubules in most cell types, oocyte spindles form and mediate meiotic chromosome segregation in their absence. Here, we used high-resolution imaging of both bipolar and experimentally generated monopolar spindles in Caenorhabditis elegans to reveal a surprising organization of microtubules and chromosomes within acentrosomal structures. We ...
Joglekar Ajit P AP Department of Biology, University of North Carolina, Chapel Hill, NC 27599, - - 2009
Dynamic attachments between kinetochores and spindle microtubules are required for chromosome bi-orientation in mitosis. A new study provides biophysical insight into how the Ndc80 complex may contribute to the formation of these attachments.
Ke Kevin K Department of Biomedical Engineering, Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, MI 48109, - - 2009
Polar ejection forces have often been hypothesized to guide directional instability of mitotic chromosomes, but a direct link has never been established. This has led, in part, to the resurgence of alternative theories. By taking advantage of extremely precise femtosecond pulsed laser microsurgery, we abruptly alter the magnitude of polar ...
Li Na - - 2009
Mitotic chromosome movements are orchestrated by interactions between spindle microtubules and chromosomes. It is well known that kinetochore is the major site where microtubule-chromosome attachment occurs. However, the functions of other domains of chromosome such as chromosome periphery have remained elusive. Our previous studies show that PinX1 distributes to chromosome ...
Sakuno Takeshi - - 2009
During cell division microtubules capture chromosomes by binding to the kinetochore assembled in the centromeric region of chromosomes. In mitosis sister chromatids are captured by microtubules emanating from both spindle poles, a process called bipolar attachment, whereas in meiosis I sisters are attached to microtubules originating from one spindle pole, ...
Qiu ShuLan - - 2009
Kinetochores are large proteinaceous structure on the surface of chromosomes' primary constriction during mitosis. They link chromosomes to spindle microtubules and also regulate the spindle assembly checkpoint, which is crucial for correct chromosome segregation in all eukaryotes. The better known core networks of kinetochores include the KMN network (K, KNL1; ...
Ferrand Alexia - - 2009
The role of the LIM-domain-containing protein Ajuba was initially described in cell adhesion and migration processes and recently in mitosis as an activator of the Aurora A kinase. In the present study, we show that Ajuba localizes to centrosomes and kinetochores during mitosis. This localization is microtubule-dependent and Ajuba binds ...
Ribeiro Susana A SA Wellcome Trust Centre for Cell Biology, Institute of Cell and Molecular Biology, University of Edinburgh, Edinburgh EH9 3JR, United - - 2009
When chromosomes are aligned and bioriented at metaphase, the elastic stretch of centromeric chromatin opposes pulling forces exerted on sister kinetochores by the mitotic spindle. Here we show that condensin ATPase activity is an important regulator of centromere stiffness and function. Condensin depletion decreases the stiffness of centromeric chromatin by ...
Welburn Julie P I JP Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Suite 401, Nine Cambridge Center, Cambridge, MA 02142, - - 2009
Mitotic chromosome segregation requires that kinetochores attach to microtubule polymers and harness microtubule dynamics to drive chromosome movement. In budding yeast, the Dam1 complex couples kinetochores with microtubule depolymerization. However, a metazoan homolog of the Dam1 complex has not been identified. To identify proteins that play a corresponding role at ...
Sivaram Mylavarapu V S - - 2009
The spindle assembly checkpoint monitors microtubule attachment to kinetochores and tension across sister kinetochores to ensure accurate division of chromosomes between daughter cells. Cytoplasmic dynein functions in the checkpoint, apparently by moving critical checkpoint components off kinetochores. The dynein subunit required for this function is unknown. Here we show that ...
Desai Parima - - 2009
High-fidelity chromosome segregation during mitosis requires kinetochores, protein complexes that assemble on centromeric DNA and mediate chromosome attachment to spindle microtubules. In budding yeast, phosphoinositide-specific phospholipase C (Plc1p encoded by PLC1 gene) is important for function of kinetochores. Deletion of PLC1 results in alterations in chromatin structure of centromeres, reduced ...
Maresca Thomas J - - 2009
Cells have evolved a signaling pathway called the spindle assembly checkpoint (SAC) to increase the fidelity of chromosome segregation by generating a "wait anaphase" signal until all chromosomes are properly aligned within the mitotic spindle. It has been proposed that tension generated by the stretch of the centromeric chromatin of ...
Oosterhof Nikolaas N - - 2009
Using a dynamic stimuli paradigm, in which faces expressed either happiness or anger, the authors tested the hypothesis that perceptions of trustworthiness are related to these expressions. Although the same emotional intensity was added to both trustworthy and untrustworthy faces, trustworthy faces who expressed happiness were perceived as happier than ...
Kelly Alexander E - - 2009
The directed movement of chromosomes during mitosis and meiosis relies on microtubule-mediated connections between spindle poles and kinetochores assembled on chromosomes. The molecular basis for the dynamic interaction between microtubules and kinetochores is just beginning to be unveiled. Here, focusing on the mitotic centromere kinase Aurora B, we review our ...
Deng Manqi - - 2009
Kinetochores are considered to be the key structures that physically connect spindle microtubules to the chromosomes and play an important role in chromosome segregation during mitosis. Due to different mechanisms of spindle assembly between centrosome-containing mitotic cells and acentrosomal meiotic oocytes, it is unclear how a meiotic spindle generates the ...
Tanaka Kozo - - 2009
For high-fidelity chromosome segregation, kinetochores must be properly captured by spindle microtubules, but the mechanisms of initial kinetochore capture have remained elusive. Observation of individual kinetochore-microtubule interaction has been difficult, because multiple kinetochores are captured by microtubules during a short period and within a small space. By isolating one of ...
Klebig Christiane - - 2009
During cell division microtubules of the mitotic spindle segregate the duplicated chromosomes into the two daughter cells. Chromosome-microtubule attachment is mediated by kinetochores, multiprotein complexes assembled on specialized regions of the DNA. Kinetochores modulate microtubule dynamics to generate the forces necessary to power chromosome movement and regulate the spindle checkpoint. ...
Samoshkin Alexander - - 2009
Condensins I and II in vertebrates are essential ATP-dependent complexes necessary for chromosome condensation in mitosis. Condensins depletion is known to perturb structure and function of centromeres, however the mechanism of this functional link remains elusive. Depletion of condensin activity is now shown to result in a significant loss of ...
Kitagawa Risa R Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA. - - 2009
In contrast to many eukaryotic organisms in which kinetochores are assembled on localized centromeres of monocentric chromosomes, Caenorhabditis elegans has diffuse kinetochores, termed holo-kinetochores, which are assembled along the entire length of the mitotic chromosome. Despite this cytologically distinct chromosomal architecture, holo-kinetochores of C. elegans and kinetochores of other eukaryotes ...
Kulukian Anita A Ludwig Institute for Cancer Research, University of California at San Diego, La Jolla, CA 92093, - - 2009
Premature anaphase onset is prevented by the mitotic checkpoint through production of a "wait anaphase" inhibitor(s) that blocks recognition of cyclin B and securin by Cdc20-activated APC/C, an E3 ubiquitin ligase that targets them for destruction. Using physiologically relevant levels of Mad2, Bub3, BubR1, and Cdc20, we demonstrate that unattached ...
Emanuele Michael J MJ Department of Biochemistry, University of Virginia, Charlottesville, VA, - - 2009
Kinetochores are multiprotein machines that initiate mitotic checkpoint signaling and control chromosome movement through interactions with microtubules. Our lab has utilized Xenopus laevis frog egg extracts to investigate the requirements for kinetochore assembly and disassembly in vertebrates. Egg extracts support the assembly of functional kinetochores that are capable of binding ...
Przewloka Marcin R MR University of Cambridge, Department of Genetics, Cambridge, CB2 3EH, United Kingdom. - - 2009
Accurate chromosome segregation is a prerequisite for the maintenance of the genomic stability. Consequently, elaborate molecular machineries and mechanisms emerged during the course of evolution in order to ensure proper division of the genetic material. The kinetochore, an essential multiprotein complex assembled on mitotic or meiotic centromeres, is an example ...
Ishigami Naoki - - 2008
Unidirectional growth of single-walled carbon nanotubes (SWNTs) was achieved using the patterned Co-Mo salt catalyst on the r-plane sapphire substrate. This is in marked contrast with the SWNTs grown on an a-plane sapphire and ST-cut quartz, on which the SWNTs grew bidirectionally. This new growth mode is not dependent on ...
Kim Wonjun - - 2009
Overlay text brings important semantic clues in video content analysis such as video information retrieval and summarization, since the content of the scene or the editor's intention can be well represented by using inserted text. Most of the previous approaches to extracting overlay text from videos are based on low-level ...
Cai Shang - - 2008
Creating stable yet flexible attachments of spindle microtubules to the kinetochore is critical for facilitating chromosome congression, segregation, and checkpoint signaling. Two new studies have elucidated the molecular details of how the Ndc80 complex mediates this dynamic attachment.
Bakhoum Samuel F SF Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755, - - 2009
Most solid tumours are aneuploid and many frequently mis-segregate chromosomes. This chromosomal instability is commonly caused by persistent mal-oriented attachment of chromosomes to spindle microtubules. Chromosome segregation requires stable microtubule attachment at kinetochores, yet those attachments must be sufficiently dynamic to permit correction of mal-orientations. How this balance is achieved ...
Shimogawa Michelle M MM Department of Biochemistry, University of Washington, Seattle, WA 98195-7350, - - 2009
The Saccharomyces cerevisiae chromosomal passenger proteins Ipl1 (Aurora B) and Sli15 (INCENP) are required for the tension checkpoint, but the role of the third passenger, Bir1, is controversial. We have isolated a temperature-sensitive mutant (bir1-107) in the essential C-terminal region of Bir1 known to be required for binding to Sli15. ...
Bojariu Roxana - - 2008
The Northern Hemisphere annular mode, also known as the Arctic Oscillation/North Atlantic Oscillation (AO/NAO) is a dominant atmospheric mode in the Northern Hemisphere winter that influences climate fluctuations from the eastern seaboard of the United States to Siberia and from the Arctic to the subtropical Atlantic. After almost a century ...
Gardner Melissa K MK Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, - - 2008
During mitosis, sister chromatids congress to the spindle equator and are subsequently segregated via attachment to dynamic kinetochore microtubule (kMT) plus ends. A major question is how kMT plus-end assembly is spatially regulated to achieve chromosome congression. Here we find in budding yeast that the widely conserved kinesin-5 sliding motor ...
Zhu Hui H Department of Biological Sciences, Stanford University, Stanford, CA 94305, - - 2008
Microtubules (MTs) are nucleated from centrosomes and chromatin. In addition, MTs can be generated from preexiting MTs in a gamma-tubulin-dependent manner in yeast, plant, and Drosophila cells, although the underlying mechanism remains unknown. Here we show the spindle-associated protein FAM29A promotes MT-dependent MT amplification and is required for efficient chromosome ...
Welburn Julie P I - - 2008
Chromosome segregation in eukaryotes requires a large molecular assembly termed the kinetochore to attach chromosomes to spindle microtubules. Recent work has made substantial progress in defining the composition and activities of the kinetochore, but much remains to be learned about its macromolecular structure. This commentary discusses recent insights into structural ...
Athale Chaitanya A - - 2008
During spindle assembly, chromosomes generate gradients of microtubule stabilization through a reaction-diffusion process, but how this is achieved is not well understood. We measured the spatial distribution of microtubule aster asymmetry around chromosomes by incubating centrosomes and micropatterned chromatin patches in frog egg extracts. We then screened for microtubule stabilization ...
McIntosh J Richard JR Department of M.C.D. Biology, University of Colorado, Boulder, CO 80309-0347, USA. - - 2008
Kinetochores of mitotic chromosomes are coupled to spindle microtubules in ways that allow the energy from tubulin dynamics to drive chromosome motion. Most kinetochore-associated microtubule ends display curving "protofilaments," strands of tubulin dimers that bend away from the microtubule axis. Both a kinetochore "plate" and an encircling, ring-shaped protein complex ...
Bloom Kerry K Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA. - - 2008
Proper chromosome segregation in mitosis requires tethering of spindle microtubules to the kinetochore. Using electron tomography of mammalian cells, McIntosh et al. (2008) now report the presence of fibrils that connect the inner kinetochore to the curved protofilaments at microtubule ends, suggesting a new model for force generation in chromosome ...
Ryan, Kenneth George
Reliable techniques for the living cell culture and correlative light and electron microscopy (EM) of meiotic pollen mother cells (PMCs) of Iris spuria, Allium triquetrum and Tradescantia flumenensis are described in detail. Living PMCs were successfully cultured in a slide chamber on agar/sucrose medium. Cells were covered with an inert ...
Kitamura Satomi - - 2009
Nitrous oxide gas (N(2)O) can be used to produce polyploid plants, but the mechanism of action is unknown. The actin and microtubule cytoskeleton was observed in N(2)O-treated microsporocytes of Lilium spp 'Asiatic hybrid lilies' using fluorescence microscopy after staining with DAPI, FITC-conjugated tubulin antibody, and phalloidin-conjugated Alexa Fluor 546. Additionally, ...
O'Connell Christopher B CB Division of Molecular Medicine, Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA. - - 2008
The accuracy of chromosome segregation is enhanced by the spindle assembly checkpoint (SAC). The SAC is thought to monitor two distinct events: attachment of kinetochores to microtubules and the stretch of the centromere between the sister kinetochores that arises only when the chromosome becomes properly bioriented. We examined human cells ...
Zhao Yongping - - 2008
The classical support vector regressions (SVRs) are constructed based on convex loss functions. Since non-convex loss functions to a certain extent own superiority to convex ones in generalization performance and robustness, we propose a non-convex loss function for SVR, and then the concave-convex procedure is utilized to transform the non-convex ...
Liu Jian - - 2008
During mitosis, chromosomes undergo a series of movements while being end-on attached to the kinetochore microtubules (KMTs) from spindle poles. The mechanism underlying such movements and their physiological functions remains elusive. We describe a mechanobiochemical feedback model of chromosome motility. The key ingredient is a feedback mechanism between the local ...
Gassmann Reto - - 2008
Chromosome segregation requires stable bipolar attachments of spindle microtubules to kinetochores. The dynein/dynactin motor complex localizes transiently to kinetochores and is implicated in chromosome segregation, but its role remains poorly understood. Here, we use the Caenorhabditis elegans embryo to investigate the function of kinetochore dynein by analyzing the Rod/Zwilch/Zw10 (RZZ) ...
Tanaka Tomoyuki U TU Wellcome Trust Centre for Gene Regulation & Expression, College of Life Sciences, University of Dundee, Dundee, Scotland. - - 2008
To maintain their genetic integrity, eukaryotic cells must segregate their chromosomes properly to opposite poles during mitosis. This process mainly depends on the forces generated by microtubules that attach to kinetochores. During prometaphase, kinetochores initially interact with a single microtubule that extends from a spindle pole and then move towards ...
Cintron,Daisy
Activating mutations in SHP-2 tyrosine phosphatase implicated in cell signaling processes have been identified in various childhood leukemias and sporadic solid tumors. However, the molecular mechanisms by which the activating mutations in SHP-2 induce malignancies are not fully understood. In this study, we investigated potential involvement of SHP-2 in chromosome ...
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