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  • Glia guide brain development in worms | Newswire
    on a new level of importance as researchers found that most brain tumors and many neurodegenerative diseases such as Alzheimer s Disease may arise from these cells suggesting the possibility that glia are more than mere support cells that cater to the needs of neurons that in fact a more dynamic dialogue between glia and neurons takes place Since then scientists inferred as much But now as similarities between vertebrate and invertebrate glial cells continue to surface this newly revealed system gives scientists an entry point from which to study this intricate cross talk in its natural environments and what happens when it goes wrong Yoshimura Shaham and colleagues have already started In two separate sets of experiments when the team either zapped two of the animal s four brain ensheathing glia with a microscopic laser or mutated genes required for these glia s normal development they found that while neurons didn t die they were abnormal and grossly so Their dendrites were dramatically shortened and their axons unable to branch to their expected locations failed to make the right connections Moreover the team showed that neurons located closer to the removed glia have a more abnormal pattern of axon branching compared to those farther away suggesting that a chemical glia secrete does in fact tell axons where to go and perhaps how to get there The scientists most dramatic finding however was the effect the loss of these glia called cephalic sheath cells had on the organization of C elegans s entire brain a tight bundle of neurons called the nerve ring Instead of developing one nerve ring 20 percent of the animals developed a chain of multiple bundles Likewise cell bodies that normally appear behind the nerve ring were dispersed throughout the head a defect that can impair

    Original URL path: http://newswire.rockefeller.edu/2008/07/11/glia-guide-brain-development-in-worms/ (2016-02-13)
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  • New method exploits old mechanism to turn genes on and off at will | Newswire
    deflects excess heat from cells and protects them from damage Since these two proteins are expressed at a specific time when organisms experience heat shock at a specific temperature scientists had long designed transgenes to be expressed the moment heat shock factor 1 binds to this sequence of DNA However while scientists could know when this transgene was expressed they couldn t limit its expression in specific cell types and study a particular protein s effect on them To do so they would have to target a single cell with a laser beam until the heat shock response kicked in for the transgene to be expressed In Caenorhabditis elegans that s 34 degrees Celsius If you re good each animal would take a couple of minutes says Shai Shaham head of the Laboratory of Developmental Genetics And you would need to repeat this many times if you wanted to study a cell s function and that cell s role in behavior To bypass this time intensive work Shaham and Taulant Bacaj a graduate student in his lab used two transgenes one called the driver the other the responder to transform mutant worms that had a deficient heat shock response in every one of their cells into those that had an intact heat shock response in just one cell type The cell type with the intact response depended on the transgenes being used In this two part system the driver consisted of a portion of DNA that was exclusively expressed in one cell type as well as the gene that encoded heat shock factor 1 the responder consisted of the promoter of a heat shock reponsive gene as well as the gene of interest Whenever Bacaj turned the dial of the incubator to 34 degrees the specific cells expressed heat shock

    Original URL path: http://newswire.rockefeller.edu/2007/12/07/new-method-exploits-old-mechanism-to-turn-genes-on-and-off-at-will/ (2016-02-13)
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  • heat shock | Newswire
    C elegans roundworms exploits this ancient mechanism to control when and where genes are expressed an ability that helps determine which cells require the expression of certain genes during different stages of development While existing techniques enabled scientists to achieve this feat this new method provides them with the same information in a fraction of the time More Tags heat shock Shai Shaham Search for Categories Science News Awards and

    Original URL path: http://newswire.rockefeller.edu/tag/heat-shock/ (2016-02-13)
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  • Small RNAs in blood may reveal heart injury | Newswire
    as indicators of injury produced by anything from heart attack to an impact in a car accident The findings were published online July 10 in the Proceedings of the National Academy of Sciences and add to a growing body of knowledge about microRNAs These small RNA molecules are encoded in the genome and they fine tune the expression of genes in the cells that produce them They also show up in the blood stream outside the protective environment of the cell Although microRNAs are present in blood at extremely low levels the highly sensitive RNA sequencing techniques used by the Rockefeller team can detect them The researchers profiled the microRNA in samples of blood and heart tissue from healthy people and people suffering from one of two types of heart failure which develops when the heart s pumping action weakens making it unable to deliver blood throughout the body They compared their microRNA results with those of a protein currently used to diagnose injury to heart muscle cardiac troponin This protein occurs within healthy heart muscle cells but when injured these cells leak cardiac troponin out into the blood stream causing its levels to spike in circulation Something similar appears to happen with microRNAs The researchers found elevated levels of muscle associated microRNAs in the blood but not in the heart tissue samples of the heart failure patients This similarity as well as other evidence suggests microRNAs could also serve as biomarkers for heart injury and the researchers hope microRNAs could even have an advantage over cardiac troponin Cells contain a small pool of soluble cardiac troponin but the majority is bound to heart muscle filaments By contrast the protein complexes that contain microRNA within the cell are fully soluble For this reason we suspect microRNAs may be more readily

    Original URL path: http://newswire.rockefeller.edu/2014/07/31/small-rnas-in-blood-may-reveal-heart-injury/ (2016-02-13)
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  • MicroRNAs play a role in cocaine addiction | Newswire
    has a well characterized capacity to suppress messenger RNA expression Earlier research by one of the coauthors of the current study Donal O Carroll at the European Molecular Biology Laboratory in Monterotondo Italy revealed that Argonaute 2 also contributes to the generation of microRNAs from their precursors but it s selective and appears to affect only a fraction of microRNAs in each cell The new study led by Anne Schaefer a senior research associate in Paul Greengard s Laboratory of Molecular and Cellular Neuroscience focused on Argonaute 2 s role in a specific subset of neurons that express the dopamine 2 receptor known as Drd2 Cocaine s addictive properties are related to its ability to increase levels of the neurotransmitter dopamine which in turn alters the activity of dopamine receptors in an area of the brain called the striatum Schaefer and her colleagues in the Greengard laboratory silenced Argonaute 2 only in Drd2 expressing neurons in mice In collaboration with Paul Kenny s group at The Scripps Research Institute they found that its deficiency greatly reduces the mice s motivation to self administer cocaine They also identified a distinct group of microRNAs that are specifically regulated by Argonaute 2 in the striatum Using a new technique that allows cell type specific microRNA analysis the researchers compared those Argonaute 2 dependent microRNAs with microRNAs that are enriched in Drd2 neurons and upregulated in response to cocaine The result was the identification of a set of 23 microRNAs that are likely to play a role in cocaine addiction and which the researchers say should be investigated further Identification of microRNAs that contribute to addiction is just a first step in the research program that aims to identify the epigenetic mechanism of addictive behavior says Schaefer Our studies suggest that the important role

    Original URL path: http://newswire.rockefeller.edu/2010/07/27/micrornas-play-a-role-in-cocaine-addiction/ (2016-02-13)
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  • Anne Schaefer | Newswire
    mental disorders such as schizophrenia New research by Rockefeller University scientists suggests microRNAs are also involved in regulating the motivation to consume cocaine a finding that could ultimately lead to new ways of combating addictive diseases in humans More Tags Anne Schaefer Argonaute 2 Laboratory of Molecular and Cellular Neuroscience MicroRNAs Paul Greengard Search for Categories Science News Awards and Honors Campus News Grants Gifts Topics Video Archive 2015 2014

    Original URL path: http://newswire.rockefeller.edu/tag/anne-schaefer/ (2016-02-13)
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  • Genome-wide map shows precisely where microRNAs do their work | Newswire
    and shut down protein production a process called RNA interference By 2006 when the Nobel Prize in medicine was given for the discovery of RNA interference scientists around the globe had even narrowed down microRNAs primary site of action to somewhere around the end of the RNA transcript What scientists couldn t nail down was the exact string of nucleotides to which the microRNAs bind along a messenger RNA transcript To understand exactly how microRNAs work you want to know their precise targets says Darnell who is a Howard Hughes Medical Institute investigator and Robert and Harriet Heilbrunn Professor at Rockefeller You want a map that tells you which messenger RNAs each microRNA targets and exactly where they are binding The problem was that on any given messenger RNA there are many sites to which a single microRNA can theoretically bind and there are hundreds of microRNAs in every cell Prior techniques primarily relying on computer predictions weren t very good at sorting through the morass of predictions to identify the real sites explains Darnell The trick to getting such a map was to freeze a snapshot of microRNAs directly bound to messenger RNA in living cells Working specifically in mouse brain tissue that s what Darnell and his team did using a technique the lab developed called high throughput sequence crosslinking immunoprecipitation or HITS CLIP In order to shut down a gene before it is translated microRNAs must be guided to their target messenger RNAs via a protein called Argonaute The Argonaute microRNA messenger RNA complex now forms a sandwich structure where the microRNA is compressed in the middle By using their technique to fuse Argonaute to these two RNAs the team was then able to identify the bound microRNA and its precise target sites across all messenger RNAs

    Original URL path: http://newswire.rockefeller.edu/2009/06/17/genome-wide-map-shows-precisely-where-micrornas-do-their-work/ (2016-02-13)
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  • For different species, different functions for embryonic microRNAs | Newswire
    function was not The naïve assumption is that if we understand what these microRNAs do in a fish or in the frog we can extrapolate to humans says Ali H Brivanlou head of the Laboratory of Molecular Vertebrate Embryology This study shows that this assumption is flawed when it comes to microRNAs Discovered in the 1990s and first named in 2001 microRNAs are single strands of RNA that put the brakes on gene expression halting the translation process that makes proteins Postdoctoral associate Alessandro Rosa picked a particular family of these chemical brakes specific to vertebrates and known to operate only in the early stages of embryogenesis shaping the fates of embryonic stem cells toward the various tissues and organs into which they will grow The microRNAs Rosa studied regulate what s known as the Nodal pathway a process central to initial cell differentiation The relative proportion of certain activator proteins called Nodals and inhibitory proteins Lefties determine how active the pathway is Rosa believed that this particular group of microRNAs disrupts the Lefties helping to sustain the Nodal pathway which is central to development And his research published last month in Developmental Cell bore that out Using a chemical technique to block the microRNA in frog embryos Rosa found that the embryos failed to develop the upper or dorsal and anterior portions of their growing bodies including the tissues that would eventually become neurons and eyes Instead their ventral part was expanded forming a belly like protrusion underneath Performing the same experiment on human embryonic stem cells he discovered a slightly different effect Markers for tissues fated to develop into the nervous system the neuroectoderm were up and markers for the mesendoderm the precursor of bones muscles and blood among other things were down The big difference the researchers

    Original URL path: http://newswire.rockefeller.edu/2009/05/14/for-different-species-different-functions-for-embryonic-micrornas/ (2016-02-13)
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