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  • Bullying alters brain chemistry, leads to anxiety | Newswire
    cage with a series of larger older mice a different one in each of 10 days The mice being territorial fight it out in a contest that the new arrival invariably loses Following the 10 minute battle the mice were separated in the same cage by a partition that keeps them physically apart but allows them to see smell and hear one another a stressful experience for the loser Given a day to rest the test mice are then put in the company of nonthreatening mice of comparable size and age The biggest change in behavior was that the traumatized mice were more reluctant to socialize with their fellow mice preferring to keep their distance compared to their unbullied counterparts The mice that had lost their battles were also more likely to freeze in place for longer periods of time and to frequently display risk assessment behaviors toward their new cage mates behaviors that have been shown to be valid indices of fear and anxiety in humans The researchers also gave a group of mice a drug that blocked vasopressin receptors which partly curbed some of the anxious behavior in the bullied mice The researchers then examined the brains of the mice particularly sections in the middle of the forebrain known to be associated with emotion and social behavior They found that mRNA expression for vasopressin receptors specifically V1bRs had increased in the bullied mice making them more sensitive to the hormone which is found in high levels in rats with innate high anxiety In humans the hormone is associated with aggression stress and anxiety disorders The surge of vasopressin receptors was especially notable in the amygdala Litvin and colleagues reported this month in Physiology Behavior How long these effects last remains an open question Other studies have found for

    Original URL path: http://newswire.rockefeller.edu/2011/03/25/bullying-alters-brain-chemistry-leads-to-anxiety/ (2016-02-13)
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  • Donald Pfaff | Newswire
    leads to anxiety Getting kicked around is no fun for anyone but researchers are finding that it s not just the body that s bruised but the brain too New experiments from Rockefeller show that mice that are repeatedly bullied by by dominant males grow unusually anxious around new company threatening or not The behavioral change seems to be in part due to a change in gene expression that increases

    Original URL path: http://newswire.rockefeller.edu/tag/donald-pfaff/ (2016-02-13)
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  • Yoav Litvin | Newswire
    experiments from Rockefeller show that mice that are repeatedly bullied by by dominant males grow unusually anxious around new company threatening or not The behavioral change seems to be in part due to a change in gene expression that increases sensitivity to vasopressin a hormone involved in a variety of social behaviors More Tags Donald Pfaff Laboratory of Neurobiology and Behavior vasopressin Yoav Litvin Search for Categories Science News Awards

    Original URL path: http://newswire.rockefeller.edu/tag/yoav-litvin/ (2016-02-13)
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  • Imaging studies reveal order in programmed cell death | Newswire
    toxic effect here but that the variability is in the molecular makeup of the cells the variability in the population Apoptosis is crucial not just in the routine maintenance of life but also in early development when some cells such as those that would otherwise form webbing between human fingers are programmed to die and in the tuning and trimming of the nervous system I like to think of it as sculpting chipping away pieces at a time to create the form Simon says A better understanding of apoptosis could help explain certain developmental disorders What s more cell death or the lack thereof is important in the pathology of some cancers in which mutant cells fail to die and grow out of control forming tumors and spreading throughout the body One potential therapeutic goal would be to learn how to trigger cell death in targeted populations like tumors Investigating the population dynamics of cell death led to the examination on a much faster timescale of what was happening inside individual cells during apoptosis Using single cell microscopy and fluorescent tags that probe for cell function or for proteins that leave the mitochondria during apoptosis graduate fellow Patrick Bhola and Postdoctoral Associate Alexa Mattheyses took pictures as the proteins dispersed through the membrane of one mitochondrion and the process spread in a wave to the other mitochondria in a cell Some scientists had assumed that this happened simultaneously to all mitochondria throughout the cell This spatial coordination means that there is an upstream signal for release that is spatially localized within individual cells says Mattheyses The idea in general was to look at individual events in the cells and see if we could get any insights that we could not get looking macroscopically at whole populations of them Simon says

    Original URL path: http://newswire.rockefeller.edu/2010/02/25/imaging-studies-reveal-order-in-programmed-cell-death/ (2016-02-13)
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  • New cell death pathway involved in sperm development | Newswire
    unwanted cellular bulk green Though quite a bit has been learned about how caspases are activated very little is known about how unwanted caspase activity is restricted so that healthy productive cells aren t mistakenly targeted for death So Steller and his colleagues wanted to figure out how caspases which are expressed in all cells are activated at the right time and at the right place and in this case how they do not kill off a cell entirely The researchers screened more than 1 000 sterile male fruit flies looking for cellular differences between sterile flies and fertile ones They then mapped these differences back to the genes to identify mutations along the Drosophila genome that made these fruit flies sterile This process eventually pointed them to three distinct genes that encode different protein components of a complex called Cullin 3 ubiquitin ligase Cullins are members of the E3 ubiquitin ligase family which labels other proteins with ubiquitin a molecule that marks them for degradation It turns out that Cullin 3 in conjunction with two other proteins activates caspases by degrading a caspase inhibitor This in turn initiates a cell death like program at the right time and at the right place in the developing testes of Drosophila and gets rid of unwanted cytoplasm and organelles Before this study only IAPs another class of E3 ubiquitin ligases had been identified as caspase regulators Now Steller and his group have found a new major player that regulates these killer proteins One of the proteins that form the Cullin based complex in Drosophila has also been linked to male infertility in mice and humans In mice a mutation in the gene that encodes a protein called Klh110 causes male sterility In humans male infertility has been linked to this gene as

    Original URL path: http://newswire.rockefeller.edu/2007/09/17/new-cell-death-pathway-involved-in-sperm-development/ (2016-02-13)
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  • Researcher discover new cell death program | Newswire
    I think everyone knew there was something a little off about the linker cell says Shaham head of the Laboratory of Developmental Genetics It undergoes a very complex migration in the male animal while the gonad develops behind it At the end of the migration the linker cell dies and the gonad fuses with an exit channel linking it with the outside environment If you kill the cell too early the gonad doesn t grow properly And we noticed that if the cell doesn t die it interferes with the fusion and sperm build up in the gonad Abraham studied all of the genes known to be involved in cell death systematically disrupting them in the animal She used broad spectrum caspase inhibitors to try to stop the linker cell from dying but nothing worked Even after all this I still wasn t able to block linker cell death which really suggested to me that this cell was dying using a different mechanism Support for this idea came when she took a closer look at the morphology of a dying linker cell She saw an accumulation of vesicles like bubbles in the linker cell and swollen organelles but apart from some nuclear membrane ruffling the nucleus looked normal None of these characteristics fit with the morphology of apoptosis the type of cell death controlled by caspases I have been in the cell death field for 17 years and I had never seen anything like it says Shaham Once again Abraham went back to the literature In a 1976 Journal of Cell Biology paper she found what she was looking for Electron micrographs of cells dying in the developing mouse nervous system showed all the same traits as her linker cell At that time characterization of programmed cell death was primarily

    Original URL path: http://newswire.rockefeller.edu/2007/01/09/researcher-discover-new-cell-death-program/ (2016-02-13)
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  • Trash talk: Molecular conversations trigger cell suicide in yeast | Newswire
    emerging evidence suggests that these chemical marks also communicate with each other engaging in crosstalk that regulates important signaling events within the cell One of these events is a type of programmed cell death called apoptosis All animal cells use apoptosis to maintain the balance with cell growth required to ensure proper development and survival To better understand how crosstalk works in gene regulation Sung Hee Ahn a graduate student in the Laboratory of Chromatin Biology and Epigenetics focused on budding yeast a simple organism with only one histone known as H2B mammalian cells typically contain thousands of histone proteins Previous research by Ahn and her colleagues showed that when hydrogen peroxide was used to induce cell death in yeast a kinase called Ste20 phosphorylated i e attached a phosphate chemical group to the amino acid serine 10 The scientists also observed that an acetyl chemical group is attached to an adjacent amino acid lysine 11 on H2B in growing yeast They asked the question do these two histone modifications in H2B talk to each other The answer it turns out is yes and in a very specific order that is deadly to the yeast cell In a study published recently in Molecular Cell Ahn and her colleagues show that the acetyl mark on lysine 11 blocks the ability of Ste20 to phosphorylate serine 10 The researchers also found that an enzyme known as Hos3 removes the acetyl group from lysine 11 when the cells are exposed to hydrogen peroxide This in turn sets in motion Ste20 which phosphorylates serine 10 and launches the suicide program in the yeast cell Based upon these findings we propose a model for regulated crosstalk in H2B wherein Hos3 directly catalyzes the deacetylation of lysine 11 which then mediates the phosphorylation of serine 10

    Original URL path: http://newswire.rockefeller.edu/2006/12/19/trash-talk-molecular-conversations-trigger-cell-suicide-in-yeast/ (2016-02-13)
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  • Sperm cells shaped by natural cell suicide mechanism | Newswire
    authors of this study include first author Eli Arama Ph D a postdoctoral associate at Rockefeller and Julie Agapite a former graduate student at the Massachusetts Institute of Technology Streamlined sperm Sperm cells in both humans and flies must go through a series of refinements before they are ready to fertilize an egg For example in the human male a finished sperm cell must be streamlined and compact so that it can make its way through the female s uterus and ultimately penetrate her egg Consequently during the final stages of this maturation process called spermatogenesis a sperm cell loses most of its volume essentially its main soupy chamber the cytoplasm almost completely breaks away leaving a highly compressed cell consisting mainly of a nucleus and a long flagellum But how sperm cells orchestrate the removal of these cytoplasmic corpses was unknown until now Cellular sacrifice An evolutionarily conserved mechanism programmed cell death operates in a diverse range of organisms from worms to humans It takes place during development to sculpt critical organs and tissues and throughout adulthood to purge the body of unwanted cells Disruptions to this latter housekeeping activity can lead to a diverse set of diseases in humans for example cancer occurs when too little cell death takes place while Alzheimer s Parkinson s and other disorders arise when too many cells are sacrificed Thanks to Steller and other scientists the nuts and bolts of programmed cell death are now better understood When it comes time for a cell to kill itself the body instructs it to do so through a series of molecular messengers that ends with the release of merciless proteins called caspases which chew up the insides of cells This same pathway holds true for humans and flies making these insects which produce some of the longest sperm cells known excellent models to study cell death Drosophila melanogaster s sperm cells are 1 8 millimeters in length while Drosophila bifurca s can reach up to 5 8 centimeters Blue whales produce sperm that are only 0 056 millimeters in length Night of the living sperm Using the fruit fly Drosophila melanogaster as their subject the Rockefeller researchers decided to test the idea that programmed cell death underlies late events in sperm differentiation To begin the researchers looked for caspase activity in developing fly sperm Activation of caspases is a key feature of apoptosis so the presence of active caspases in spermatids indicated the presence of this process says Arama They applied caspase inhibitors to these cells the equivalent of throwing a wrench in the cell death machinery and observed that healthy sperm no longer resulted Instead the sperm cells still carried excess cytoplasmic baggage indicating that caspase activity must contribute to the shaping of fertile sperm cells Examining mutant infertile flies next the scientists discovered more than they hoped for In addition to identifying an infertile fly with defects in its ability to activate caspases proof that programmed cell death underlies infertility they also

    Original URL path: http://newswire.rockefeller.edu/2003/05/19/sperm-cells-shaped-by-natural-cell-suicide-mechanism/ (2016-02-13)
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