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  • Two forces of arousal converge on the “satiety center” of the brain | Newswire
    against the need for sleep scientists led by Donald Pfaff head of the Laboratory of Neurobiology and Behavior gradually shifted the mice s mealtime during the night when mice are most active to a four hour window during the day when they are usually at rest Three days after the mealtime shift the mice began to show classic signs of anticipatory behavior wheel running an hour or two before the timed meal Compared to control animals the shifted mice ran three times the distance on the wheel increased activity signaling a heightened sense of alertness This behavior also suggests that the light dark cycle no longer regulated the mice s behavioral arousal food did The researchers used immunocytochemistry to test where in the brain these two arousal pathways converge Out of the 16 brain regions tested only one had become activated the ventromedial hypothalamus a group of neurons known as the satiety center of the brain Animals including humans tend to stop eating when this region is activated and damage to this group of neurons leads to obesity The activity of the paraventricular nucleus a region that produces many hormones was decreased Since we examined the brain as close as possible to the development of this anticipatory behavior says postdoc Ana Ribeiro the neuronal changes we observed are the ones most likely causing the changes in behavioral arousal These regions are thus the best targets for modulating arousal Although the research which appears in the December 11 issue of the Proceedings of the National Academy of Sciences was performed on mice it has implications for humans First author Ribeiro explains that to optimize performance on tasks that require sustained vigilance ones performed by air traffic controllers physicians the military and others understanding the neural mechanisms and molecules involved in mediating

    Original URL path: http://newswire.rockefeller.edu/2008/01/08/two-forces-of-arousal-converge-on-the-satiety-center-of-the-brain/ (2016-02-13)
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  • satiety | Newswire
    mental alertness animals are typically alert during one part of the cycle and not so alert during the other New research from Rockefeller University shows how changing the timing of a meal can disrupt these patterns and reveals which regions of the brain are involved More Tags circadian clock Donald W Pfaff hunger satiety Search for Categories Science News Awards and Honors Campus News Grants Gifts Topics Video Archive 2015

    Original URL path: http://newswire.rockefeller.edu/tag/satiety/ (2016-02-13)
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  • Single circadian clock regulates flies’ response to light and temperature | Newswire
    12 hour intervals After a few days of temperature variability the scientists then held the temperature steady in the warm phase at about 77 degrees Fahrenheit to see whether their molecular clocks continued to cycle in the absence of temperature fluctuations When they looked at gene activity in the flies heads where their light sensing capabilities are located the researchers found a great deal of overlap between those genes that oscillate in response to cycles of light and dark and those that oscillate according to cycles of temperature Upon closer examination they saw that although temperature regulated genes also appear to be activated by light as indicated by measurements of the transcripts the genes produce the opposite was not true Not all light regulated genes fluctuate with temperature So it seems that the temperature transcripts are a subset of the light transcripts says Catharine Boothroyd a postdoc in the lab and the paper s first author This she says means that the temperature responsive genes are not controlled by a separate circadian clock Even more interesting the researchers found that the transcriptional patterns of light and temperature genes are offset by about six hours with light peaking earlier than temperature a pattern that mirrors the ups and downs of the natural environment in which temperature is lowest around dawn and highest near sunset And what happens if the single clock gets conflicting light and temperature signals Over the ranges that Boothroyd and Young tested temperature turned out to be the weaker of the two stimuli If you give the fly appropriate phases of light and temperature it maintains its activity as it would in light alone Boothroyd says But if you give it light and temperature in the opposite phases light during cooler temperatures and darkness during warmer ones the

    Original URL path: http://newswire.rockefeller.edu/2007/05/07/single-circadian-clock-regulates-flies-response-to-light-and-temperature/ (2016-02-13)
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  • New function for protein links plant’s circadian rhythm to its light-detection mechanism | Newswire
    environment In many organisms an internal body clock maintains a twenty four hour cycle a circadian rhythm that dictates when to sleep and when to eat The circadian rhythm in plants tells them what season it is and when to flower for the best chance of attracting insects to pollinate them Plants set their clocks by detecting the light cycle and Chua s lab found that an accessory protein called SPA1 is important for keeping the internal clock set When they bred Arabidopsis plants with a mutated SPA1 protein the plants flowered early producing shoots and flowers weeks ahead of wild type plants Trouble keeping time The external light cycle helps wild type plants left set their circadian clock which then regulates when they flower But plants with a mutation to their SPA1 gene right begin their flowering cycle weeks too soon The regulation of flowering initiation in response to the length of the day is mediated by the interaction of light with the plant s circadian clock system says Chua Plants detect light with proteins called phytochromes and cryptochromes SPA1 regulates one of these phytochromes called PhyA The PhyA protein links light detection with the circadian clock system and directly influences when a plant flowers But Chua s finding suggests that SPA1 normally represses PhyA function holding the plant back from flowering until the right time We knew that SPA1 negatively regulated PhyA immediately after germination but didn t know if it played a role in the adult says Chua Our results show that SPA1 is important in the adult for regulating PhyA and the circadian period When SPA1 is mutated the plants precociously flower affecting their entire reproductive cycle The research has applications in agriculture a better understanding of plants circadian rhythms could help farmers stagger crop harvests

    Original URL path: http://newswire.rockefeller.edu/2006/10/06/new-function-for-protein-links-plants-circadian-rhythm-to-its-light-detection-mechanism/ (2016-02-13)
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  • Nam-Hai Chua | Newswire
    flower because they set their circadian clocks by measuring the length and quality of the light they receive Now Rockefeller University researchers have found a new function for the protein SPA1 showing that it serves as an important link between a plant s light detection proteins and the rest of its circadian clock machinery More Tags circadian clock Nam Hai Chua July 26 2005 Science News Protein destruction helps plants enter a different life stage As a seed awakens and begins to sprout it must make a decision does it have everything it needs to grow or should it wait for better conditions The choice rests on the presence or absence of one protein ABI3 and new research from the laboratory of Nam Hai Chua Ph D at Rockefeller University provides insight on how ABI3 s presence is controlled More Tags Nam Hai Chua July 7 2003 Science News From creatures of the dark to photosynthesizing green beings A plant born into darkness underneath a blanket of soil and leaves will grow long and thin its spindly stem stretching up towards the hidden sun When at last it reaches the light the plant will sprout green leaves thicken its stem and begin to breathe a coordinated effort involving the switching on of hundreds of genes More Tags COP1 Nam Hai Chua ubiquitination February 4 2003 Science News Young plant s natural defenses amount to more than just its seed An infant plant sleeps peacefully within its seed entirely shielded from drought and other harsh conditions that might otherwise threaten its well being When the time comes at last to wake up and stretch its budding leaves the young seedling must do so very carefully once it decides to enter the unpredictable world outside there s no turning back to the

    Original URL path: http://newswire.rockefeller.edu/tag/nam-hai-chua/ (2016-02-13)
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  • New research shows how proteins make biological clock tick | Newswire
    proteins idle in a cell s cytoplasm until they bump into each other and then bound together enter the nucleus But Young and Pablo Meyer who was then a graduate student in Young s lab used a novel method to show that this scenario was far too simple Meyer a physicist by training found himself frustrated by how little he could see of what was occurring in a cell The truth is we really don t know mechanistically what happens in the cytoplasm and how things are being done in such a precise way Meyer says So he turned to a technique invented in 1948 called Fluorescence Resonance Energy Transfer FRET gauges interactions between proteins by fluorescently tagging them and measuring how they react to different wavelengths of light But the technique is complicated and no one had ever thought to use it to follow proteins in a single cell for an extended period of time Young explains how FRET works This begins to measure all these biochemical interactions inside the cell Meyer says For the first time Period and Timeless could be tracked within a cell for eight hours or longer No one had ever labeled the components to follow them over time to see one clock as it ticks away in a single cell Young says All the biochemistry and molecular biology that had been done on this had been piecing together information from dead flies Now instead of freeze frames they had a movie See image at right The movie allowed them to follow the interactions between Period and Timeless with a resolution never before possible They discovered that rather than randomly colliding the two proteins bind together in the cytoplasm almost immediately and create what Young and Meyer refer to as an interval timer Then six

    Original URL path: http://newswire.rockefeller.edu/2006/01/11/new-research-shows-how-proteins-make-biological-clock-tick/ (2016-02-13)
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  • FRET | Newswire
    several hours Rockefeller scientists have turned the old model of the cellular circadian clock on its head When the two proteins come together the scientists say they create a six hour timer that appears to tightly regulate the cell s circadian rhythm More Tags circadian clock FRET Michael W Young Search for Categories Science News Awards and Honors Campus News Grants Gifts Topics Video Archive 2015 2014 2013 2012 2011

    Original URL path: http://newswire.rockefeller.edu/tag/fret/ (2016-02-13)
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  • Scientists Identify New Gene That Controls Sleep/Wake Cycle | Newswire
    s body cycle The fly circadian cycle begins around noon when the per and tim genes become active making RNA molecules essential to create the PER and TIM proteins but only after sunset does the accumulated RNA prompt the cell to stockpile the PER and TIM proteins At night the proteins pair in the cytoplasm and then migrate into the nucleus home to cells genetic material It is this movement to the nucleus that signals the per and tim genes to stop making RNA and hence new PER and TIM proteins Near dawn the old PER TIM protein pairs disintegrate With the proteins depleted the per and tim genes begin to make RNA again by midday The pace of the clock is set by a time lag while the per and tim genes are freed to make RNA early in the day PER and TIM protein pairs form at night Previous work by Young s laboratory hinted that this delay was caused by the late arrival of one of the two protein partners PER Accumulation of PER is postponed because PER proteins are rapidly broken down in the cytoplasm when they are not paired with TIM The new gene double time regulates this process Young and co workers named double time after the way in which it affects the length of the fly s daily cycle Both fruit flies and humans have activity rhythms that adapt perfectly to a 24 hour cycle of night and day but the researchers identified three mutants of double time that alter this cycle The first produces an 18 hour clock among the fastest of all other fruit fly clock mutants The second mutation slows down the fly s clock to about 28 hours The third mutant blocks the circadian cycle altogether The last mutant which lacks the protein product of the double time gene provided the clues to deciphering the mechanism behind the circadian oscillations The researchers found that in the mutants lacking double time protein very high levels of PER protein accumulate in the cytoplasm and these PER proteins no longer disintegrate when not paired with TIM meaning that both PER and TIM proteins are produced at the same time Without the usual time lag PER and TIM can pair and move into the nucleus prematurely In other words the double time gene regulates the buildup of PER in the cell This determines the time it takes to complete the cycle or whether there is any cycle at all says Young Young and his co workers cloned the double time gene and found that it produced an enzyme called a kinase a protein that phosphorylates or places phosphate molecules on other proteins Scientists have known for some time that PER proteins are phosphorylated with a rhythm In the double time mutants however PER proteins are overproduced and are not phosphorylated We think that the way double time regulates this cycle is to hold down the rate of accumulation of PER protein by phosphorylating

    Original URL path: http://newswire.rockefeller.edu/1998/07/10/scientists-identify-new-gene-that-controls-sleepwake-cycle/ (2016-02-13)
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