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  • Humans, flies smell alike, neurobiologists find | Newswire
    behaviorally to odors says Andreas Keller first author of the paper and a postdoc in the laboratory of Chemers Family Associate Professor Leslie Vosshall Keller designed experiments to look at exactly how a single fly would behave when exposed to different odors He and Vosshall found that both flies and humans judge odor intensity the same way but differ in their judgment of quality In flies as in humans the olfactory system is composed of nerve cells each of which expresses an odorant receptor Each receptor recognizes a small set of odors and it is the combination of the nerves that respond to each odor that generates our or the fruit fly s reaction to the smell Each animal has a different number of these odorant receptors there are 1 200 in mice 400 in humans and 61 in fruit flies Vosshall and Keller wanted to know how it is that humans and fruit flies can coexist and develop such very different numbers of odorant receptors It is not well understood how the varying numbers of odorant receptors impact odor perception across the different species says Vosshall Our research found that while determining the intensity of an odor is conserved in humans and flies odors that smell similar to a human do not necessarily smell similar to a fly There may be fundamental variations in the properties of the fly and human olfactory systems that cause the difference Vosshall and Keller also saw that the contribution of a specific odorant receptor could not be predicted based on its physiological function When they genetically removed single odorant receptors from a fly they could not predict how that would change the fly s behavior It may be that by removing just one receptor it changes the whole olfactory system and produces an

    Original URL path: http://newswire.rockefeller.edu/2007/03/23/humans-flies-smell-alike-neurobiologists-find/ (2016-02-13)
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  • New research retraces connections between nose and brain | Newswire
    olfactory bulb is actually more important for the internal structure of the glomeruli And furthermore even though all of the neurons that extend axons to the same glomerulus express the same odorant receptor they don t all respond equally to the incoming odor Since its discovery 20 years ago OCAM has been thought to play a leading role in how the connections between the nose and the olfactory bulb are established OCAM which stands for olfactory cell adhesion molecule is believed to interact only with other OCAM proteins which causes it to act like glue between neurons Mombaerts in collaboration with Andreas Walz at Rockefeller and with Helen Treloar and Charles Greer at Yale University removed the OCAM gene from mice by using a technique of genetic manipulation To their surprise the organization of the connections between the nose and the olfactory bulb seemed quite normal We tested all of the standing hypotheses of OCAM s role by generating mice missing the OCAM gene says Mombaerts who published the findings in Molecular and Cellular Neuroscience But we found no obvious effects on the topography of the olfactory system Even better the mutant mice actually had a better sense of smell in some regards But what we did see was that structures inside the individual glomeruli were disrupted The Greer Lab at Yale previously reported that glomeruli are normally separated into two compartments one where the incoming neurons interact with specialized interneurons and a second compartment where these interneurons interact with second order neurons in the olfactory pathway Greer speculated that the compartmentalization of synaptic circuits within glomeruli may help the neurons coordinate their activity But in mice missing OCAM these two compartments were no longer defined and the different types of connections were more mixed Mombaerts and his colleagues theorized that while the mice may be more sensitive to odors they may not be able to discriminate between them as well without this compartmentalization Meanwhile a second paper by Mombaerts published in Proceedings of the National Academy of Sciences reports how the different neurons that express the same odorant receptor and project their axons to specific glomeruli respond when they detect an odor In a collaboration with Anne Vassalli at Rockefeller Gordon Shepherd at Yale University and Xavier Grosmaitre and Minghong Ma at the University of Pennsylvania Mombaerts shows that neurons expressing a receptor called MOR23 can respond to the same odor with dramatically different sensitivities The scientists used a technique called perforated patch clamp recording which is often used to record the electrical currents in nerve cells but had not been applied to mouse olfactory neurons that express the same odorant receptor A very small glass tube containing an electrode is sealed to a small patch of the neuron s membrane and then the membrane is ruptured just under this micropipette giving it access to the interior of the cell The electrode can record minute changes in electrical properties and currents within the cell letting the scientists get direct

    Original URL path: http://newswire.rockefeller.edu/2006/05/15/new-research-retraces-connections-between-nose-and-brain/ (2016-02-13)
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  • When mice choose mates, experience counts | Newswire
    cues says Pfaff who is head of the Laboratory of Neurobiology and Behavior It could also be seen as a female trusting the mate choice of another female That one female s choice of mate could influence the choices of other females is well documented in birds and fish but had not been documented for any mammalian species Pfaff says that the female mice s mate preference was so strong that they even preferred the combined male female scent when it was tainted with the scent of infectious parasites opting for that over the scent of a healthy lone male Male odors can provide female mice with information on their quality condition health and suitability as a potential mate says Pfaff This type of public information uses cues inadvertently provided by an individual such as odor which others observe and use to make decisions such as mate choice food location or presence of danger Specifically in birds and fish public information has been shown to play a role in when and what to eat and whom to mate with but its use in mate choice has not been seen in mammals Pfaff who is interested in how brain chemicals affect behavior says the decisions made by the female mice hinged on the presence of oxytocin a neurotransmitter associated in humans with bonding trust and sexual attraction When the gene for oxytocin was missing female mice no longer preferentially chose male odors paired with other female odors and they did not avoid the odors of infected males though other tests showed that their olfactory system was perfectly intact Our research shows that the oxytocin gene is involved in the processing and integration of inadvertent social information used in directing mate choice in female mice says Pfaff Of course we don t

    Original URL path: http://newswire.rockefeller.edu/2006/03/21/when-mice-choose-mates-experience-counts/ (2016-02-13)
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  • Study shows a fundamental difference between how insects, mammals detect odors | Newswire
    The requirement for one odorant receptor OR83b acting in the detection of many odors is very unusual says Richard Benton a postdoc in Vosshall s lab and first author of the paper This led us to think that OR83b must be doing something important with the other receptors but exactly what it was doing was unclear Using the genetic trickery available in fruit flies we began to address this question in the sensory neurons themselves Benton and colleagues found that when OR83b is not expressed the other receptors never make it out of the endoplasmic reticulum the cellular structure in which they are made When OR83b is put back into the neurons however the other odorant receptors can now localize to the sensory cilia where they are exposed to odor molecules and stay there as long as OR83b continues to be expressed As soon as OR83b is taken away again the receptors start disappearing You first need OR83b to get the other receptors to the sensory cilia says Benton But it is also required to maintain them in the sensory membranes However OR83b doesn t need any of the other odorant receptors to get to the membrane It s special which indicated to Benton and his colleagues that it must link the other receptors to the protein trafficking pathway To determine which parts of the receptors mediate these interactions they did some computational analysis of the receptor protein sequences Their results confirmed what had already been known that these proteins spanned the cell membrane But this analysis led to a surprising discovery that the proteins looked nothing like G protein coupled receptors which are the odorant receptors in mice and humans Stemming from mammalian work in the late 1980s the whole focus in this field was on odorant receptors being

    Original URL path: http://newswire.rockefeller.edu/2006/01/20/study-shows-a-fundamental-difference-between-how-insects-mammals-detect-odors/ (2016-02-13)
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  • Watching fruit fly larvae crawl towards odors provides clues to how smells are detected | Newswire
    been working to understand for years Animals including fruit flies mice and humans detect smells through proteins called odorant receptors These molecules are found at the ends of specialized nerve cells called olfactory sensory neurons Scientists believe that because there are many more odors than there are odorant receptors humans for example have just 400 odorant receptors with which to detect thousands of distinct scents smell is sensed by a combinatorial code Meaning that one receptor can detect many different odors and one odor can interact with numerous receptors and it is the integration of each signal that the brain interprets The anatomy of the fruit fly olfactory system is similar to the human and mouse systems says Vosshall Though larvae are much simpler they have only 21 olfactory sensory neurons and about 25 odorant receptor genes These are very manageable numbers and we can completely manipulate the biology of this animal to dissect how they detect odors In work pioneered by two graduate students in her lab Elane Fishilevich and Ana Domingos a system was created in which olfactory neurons could either be shut off one at a time or shut down all together then single neurons added back The contributions of each neuron to a larva s ability to detect odor were measured based on the larva s movement towards an odor source You can t ask the larvae are you smelling or not smelling says Vosshall But you can watch them crawl on a plate and through some sophisticated statistics determine if they are detecting an odor or not What Vosshall and colleagues found was that there is that the different neurons and receptors have some overlap in the odors that they can detect Taking away single neurons did not affect the animals in major ways and

    Original URL path: http://newswire.rockefeller.edu/2005/12/21/watching-fruit-fly-larvae-crawl-towards-odors-provides-clues-to-how-smells-are-detected/ (2016-02-13)
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  • In flies, odorant receptors work together | Newswire
    of scents despite their limited array of just 62 receptors Vosshall and Fishilevich who study the olfactory system of fruit flies as a model for understanding how mammals detect smells looked at 49 odorant receptors proteins that detect scents and matched up which nerve cells are linked to which receptors to create an olfactory map for the fly In doing so they discovered an important difference between flies and mammals In mammals the rule is one neuron one receptor the researchers say During development when a nerve cell chooses a receptor that receptor helps guide the nerve to the correct location in the brain The presence of two receptors would lead to major confusion In the fruit fly however this rule does not apply We found that about 15 percent of the odorant receptors are co expressed in the fruit fly something that does not happen in mammals says Vosshall who is head of Rockefeller s Laboratory of Neurogenetics and Behavior This is more than just a rare exception and we didn t even look exhaustively through all the combinations Based on their research and previous findings Vosshall and Fishilevich propose that in some cases one of the receptors might be repressing the other This might help different nerve cells be more specific in the smell to which they respond Co expressing different odorant receptors may allow the fly to build different combinations that can help a nerve cell respond to a unique set of smells says Vosshall We still have to test this idea directly but the frequency of it in the fly means it is definitely something we have to pay attention to Another finding also emerged from the study Certain odorant receptors the researchers found connect directly to an area of the brain that has been linked

    Original URL path: http://newswire.rockefeller.edu/2005/09/09/in-flies-odorant-receptors-work-together/ (2016-02-13)
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  • “Blinding” an insect’s sense of smell may be the best repellent | Newswire
    corn earworm moth which damages corn cotton and tomato crops and the malaria mosquito which targets humans They found that one gene shown to be responsible for the sense of smell in fruit flies has the same function in these pest insects which are separated by over 250 million years of evolution While all these insects have sensitive olfactory systems they all have very different smell preferences says Vosshall head of the Laboratory of Neurogenetics and Behavior Yet this odorant receptor is highly conserved across all of these different species Vosshall s laboratory previously published research demonstrating that out of 62 odorant receptors in the fruit fly only a single one named Or83b was essential the sense of smell in fruit flies When they removed the gene the mutant flies couldn t smell a wide variety of different odors The scientists then examined the fruit fly s 61 other odorant receptors and found that the proteins never made it to the ends of the olfactory neurons called dendrites where they would normally interact with the different incoming smells The odors that interest flies in the outside world float around in the air until they contact tiny hairs on the fly s antennae Vosshall says The odors pass through tiny holes in the hairs where they bind the odorant receptors at the ends of nerve cells But in the mutant flies those odorant receptors fail to be delivered to the nerve endings or dendrites As a result the flies are blind to smells Odorant receptor proteins even within one species are very different from one another Researchers think that each of these receptors binds a different set of smell molecules helping the insect recognize a large number of odors in the environment When comparing the receptors across species there are groups of receptors that are only found in mosquitoes and then different groups specific to fruit flies These differences most likely tailor each insect s sense of smell to its preferred plant or animal target For fruit flies these receptors may help the fly target rotting fruit and in malaria mosquitoes they are probably specific for human body odor But Or83b is highly similar among insects regardless of their particular smell preferences Vosshall and colleagues placed Or83b from the different species into mutant fruit flies that were missing their own Or83b gene to determine if the function of the protein was also conserved They found that even though the genes were from very different species these genes from other insects restored the fly s sense of smell Then they looked closer at the olfactory nerve cells While in mutant flies the other odorant receptors were never transported to the dendrite the receptors in flies making Or83b from the different species were all correctly located at the ends of the olfactory neurons Though it remains to be shown that the different Or83b genes are similarly essential for the sense of smell in each respective insect species Vosshall is confident that this information

    Original URL path: http://newswire.rockefeller.edu/2005/02/21/blinding-an-insects-sense-of-smell-may-be-the-best-repellent/ (2016-02-13)
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  • Robert Darnell elected to National Academy of Sciences | Newswire
    they arise in conjunction with immune responses to cancer In addition to his appointment at Rockefeller Darnell is an investigator of the Howard Hughes Medical Institute and is president and scientific director of the New York Genome Center The National Academy of Sciences is a private nonprofit institution that was established under a congressional charter signed by President Lincoln in 1863 The academy recognizes achievement in science through election to its membership and it also provides science engineering and health policy advice to the federal government and other organizations It includes the National Academy of Engineering Institute of Medicine and National Research Council The newly elected members to the academy bring the total number of active members to 2 214 and the total number of foreign associates to 444 Bob Darnell s research on paraneoplastic neurologic disorders and on RNA binding proteins in the brain is groundbreaking and is highly deserving of this superb recognition from the National Academy of Sciences says Marc Tessier Lavigne Rockefeller s president In addition to his research Bob is a leader in the scientific community both at Rockefeller and in New York City as the first president of the New York Genome Center In addition to his work on PNDs which has led to new antitumor strategies now being tested in cancer patients Darnell and his team have also discovered neuron specific systems that regulate RNA expression and have developed a technique to study RNA regulation in vivo known as HITS CLIP His studies of mRNA splicing translation and miRNA regulation in clinical and experimental settings are offering new ways to explore the dark matter of the human genome and to overlay genome wide sequence information with human diseases including brain disease and cancer With Darnell s election Rockefeller now boasts 34 members or

    Original URL path: http://newswire.rockefeller.edu/2014/04/29/robert-darnell-elected-to-national-academy-of-sciences/ (2016-02-13)
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