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  • Christian Zierhut | Newswire
    of cell division such as the formation of the support structure for the envelope that surrounds the nucleus depend on the presence of DNA organizing proteins known as histones More Tags cell division Christian Zierhut Hironori Funabiki histones mitotic spindle nuclear envelope nuclear pore complex nucleosomes Search for Categories Science News Awards and Honors Campus News Grants Gifts Topics Video Archive 2015 2014 2013 2012 2011 more About Contact Follow

    Original URL path: http://newswire.rockefeller.edu/tag/christian-zierhut/ (2016-02-13)
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  • nucleosomes | Newswire
    cell division such as the formation of the support structure for the envelope that surrounds the nucleus depend on the presence of DNA organizing proteins known as histones More Tags cell division Christian Zierhut Hironori Funabiki histones mitotic spindle nuclear envelope nuclear pore complex nucleosomes Search for Categories Science News Awards and Honors Campus News Grants Gifts Topics Video Archive 2015 2014 2013 2012 2011 more About Contact Follow rockefelleruniv

    Original URL path: http://newswire.rockefeller.edu/tag/nucleosomes/ (2016-02-13)
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  • Friction harnessed by proteins helps organize cell division | Newswire
    the direction in which they are being moved along a microtubule As a result the MAPs can be shuffled into position clustered at the points of the football for example without directly consuming any energy By contrast other proteins involved in this process known as motor proteins consume chemical energy to move the microtubules around To figure out how MAPs respond to the movement of the microtubules the researchers measured the friction generated while each of three MAPs were in contact with moving microtubules For two of the three they found an asymmetry Motion in one direction generated much less friction than motion in the other direction For example the NuMA protein experienced less friction when being moved toward the minus end of the microtubule than when being moved toward the plus end while the EB1 protein showed the opposite a preference for the plus end Forth compares this asymmetry to a Chinese finger trap When two fingers inserted into both ends of the trap s tube are pulled outward away from one another the trap tightens but when both fingers are pushed in together the trap loosens This asymmetry in force is also true for these MAPs If they are dragged one way along the microtubule it is hard to do it while if they re dragged the other way it is easy to do it he says Experiments also revealed that as pairs of microtubules were jiggled these proteins shuffled along them in the direction of least resistance toward either the plus or minus end of the microtubules This discovery helps explain how NuMA for example stays clustered at the minus ends of the microtubules where it holds them together and forms a focal point for the microtubules Meanwhile one of the MAPs PRC1 showed no asymmetry in

    Original URL path: http://newswire.rockefeller.edu/2014/04/15/friction-harnessed-by-proteins-helps-organize-cell-division/ (2016-02-13)
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  • nonmotor microtubule associated proteins | Newswire
    can harness the movement around them to do their work Movement of filaments within the structure responsible for cell division can cause some of these proteins to shuffle along the path of least resistance and into position More Tags cell division mitotic spindle nonmotor microtubule associated proteins Scott Forth Tarun Kapoor Search for Categories Science News Awards and Honors Campus News Grants Gifts Topics Video Archive 2015 2014 2013 2012

    Original URL path: http://newswire.rockefeller.edu/tag/nonmotor-microtubule-associated-proteins/ (2016-02-13)
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  • Checkered history of mother and daughter cells explains cell cycle differences | Newswire
    account of its size This tidy explanation now gives way to a more nuanced version the seeds of which can be traced to research from the University of Wisconsin in 2003 It was then proposed that the size of the daughter cell has no bearing on whether it is ready to divide What matters is that the daughter cell and not the mother cell receives a protein called Ace2 at the time the two cells are born This model was against the accepted dogma and against our own previous findings Our work was an attempt to resolve the debate says Di Talia Di Talia and Frederick R Cross head of Rockefeller s Laboratory of Yeast Molecular Genetics and a researcher who like the Wisconsin group works with budding yeast seem to have reconciled the two theories and in the process nailed down new details in findings reported this week in the journal PLoS Biology The researchers found that both mothers and daughters do control and sense their size before committing to divide but the levers and gears that they use to make that commitment are different The reason Daughters but not mothers receive the protein Ace2 as well as a never before implicated protein called Ash1 which like Ace2 controls the levers that crank genes into gear In their work Di Talia and Cross studied a phase of the cell cycle known as G1 during which cells determine whether they are healthy enough to enter another grueling phase of division G1 is considered critical because mistakes in this process can lead to cancer Di Talia and Cross with colleagues Bruce Futcher and Hongyin Wang at SUNY Stony Brook found that daughter cells which normally have Ace2 and Ash1 interpret their size as 20 percent smaller than their birth twin The

    Original URL path: http://newswire.rockefeller.edu/2009/10/19/checkered-history-of-mother-and-daughter-cells-explains-cell-cycle-differences/ (2016-02-13)
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  • A positive-feedback system ensures that cells divide | Newswire
    sync Positive feedback mechanisms allow cells to adapt to changes in their environment rapidly and efficiently In the case of cell division the key is a pair of molecules called Cln1 and Cln2 part of a family of proteins known as G1 cyclins Skotheim and his colleagues including graduate student Stefano Di Talia show that when budding yeast Saccharomyces cerevisiae cells sense that they are big enough to divide they synthesize an activator molecule that triggers a positive feedback system in which Cln1 and Cln2 advance their own expression So what happens is that the very rapid ramp up of the G1 cyclins during Start lead to all those target genes getting fired synchronously says Skotheim It s a function of positive feedback that hasn t been thought of before synchrony and coherence For the genes to be fired synchronously a protein called Whi5 must be exported from the nucleus and kept out until the two daughter cells are born During Start which lasts approximately three minutes Cln1 Cln2 and the activator molecule all collaborate to kick out Whi5 Once out Cln1 and Cln2 must continue to advance their own expression in order to keep Whi5 out Then the moment the two daughter cells separate the G1 cyclins are inactivated Whi5 enters back into the nucleus and the complex detaches In previous work the team showed that the export of Whi5 is the molecular event that signals Start Now they show that a positive feedback mechanism is what drives it In the past when scientists tested the possibility that positive feedback could be behind cell division the results always came out negative But Skotheim took a different approach from that of his predecessors Instead of averaging the results across many cells he looked at data from individual cells an approach

    Original URL path: http://newswire.rockefeller.edu/2008/08/06/a-positive-feedback-system-ensures-that-cells-divide/ (2016-02-13)
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  • Frederick R. Cross | Newswire
    cell division is governed by a master oscillator coordinating with independent oscillators that control individual events Their model suggests that this orderly orchestration is analogous to how our circadian rhythm syncs with the light dark cycle in our environment More Tags Cdc14 Frederick R Cross Laboratory of Yeast Molecular Genetics August 6 2008 Science News A positive feedback system ensures that cells divide Every time a cell makes the decision to divide it faces a formidable task synchronizing the activity of hundreds of genes and proteins so that two daughter cells can be born Now Rockefeller University researchers show that a positive feedback loop helps keep these events in sync a finding that has eluded scientists for decades More Tags cell division Frederick R Cross August 1 2002 Science News What inspires yeast cells to divide Often in science a novel set of experiments comes along that forces researchers to abandon old models in exchange for new ones that better fit their observations This is the case in a new Nature report by Rockefeller University researchers which finds that past models of cellular division in the simple yeast organism were focused on the wrong protein More Tags cell division Frederick

    Original URL path: http://newswire.rockefeller.edu/tag/frederick-r-cross/ (2016-02-13)
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  • Dividing cells find their middle by following a protein ‘contour map’ | Newswire
    duplicate separate and move to the outer edge of the cell while the cell membrane pinches inward in the middle to form a structure called the cleavage furrow In order to do this the cell must know where its middle is Kapoor working with colleagues in his laboratory and at the University of Virginia School of Medicine tracked the activity of a key regulator of mitosis a protein called Aurora B Aurora is a kinase an enzyme that attaches phosphate chemical groups to proteins in a process called phosphorylation Other enzymes called phosphatases reverse this process by removing phosphates To follow Aurora activity the researchers in collaboration with Alison North of Rockefeller s Bio Imaging Resource Center adapted a powerful microscopy technique called FRET imaging which measures how close two fluorescent molecules are to each other Chemical modification of proteins cannot easily be visualized with microscopes so Kapoor and his colleagues engineered a biosensor to measure the balance between phosphorylation by Aurora and dephosphorylation by phosphatases The biosensor was anchored to different sites in the cell the equivalent of positioning a microphone at different locations in a room and then the scientists analyzed how the information changed over time The findings Proteins in the middle of the cell had a higher probability of being phosphorylated by Aurora kinase than those located near the edges Aurora kinase essentially generates a protein chemistry based contour map which tells individual molecular players where the middle is says Kapoor And the middle is where there would be the highest probability of being modified by Aurora kinase It s roughly equivalent Kapoor says to a self organizing school of fish in which fish in the middle feel something different than the fish on the edges What s really exciting is the discovery of a phosphorylation

    Original URL path: http://newswire.rockefeller.edu/2008/06/30/dividing-cells-find-their-middle-by-following-a-protein-contour-map/ (2016-02-13)
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