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Lalfabeto degli odori Anna Menini Neurobiology Sector International School for Advanced Studies Trieste, Italy.

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Presentation on theme: "Lalfabeto degli odori Anna Menini Neurobiology Sector International School for Advanced Studies Trieste, Italy."— Presentation transcript:

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2 Lalfabeto degli odori Anna Menini Neurobiology Sector International School for Advanced Studies Trieste, Italy

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5 X CN cyanide SH X thiol NH 2 X amine Br X Halides Common Odor Compounds formiates X OH alcohols COOH X carboxylic acids X R O aldehydes X O H O X H O ketones esters X R OR X alkanes

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7 What is a transduction process? A transduction process is how the energy of an external stimulus is converted into an electrical signal

8 Sensory cells convert a stimulus into an electrical response by a process known as SENSORY TRANSDUCTION

9 1- IONOTROPIC 2- METABOTROPIC How many mechanisms of transduction? C l R G Na + Ca 2+ Na Light molecules

10 Receptor potential= Generator potential The change in membrane potential produced by the stimulus is a graded potential and can be: positive or depolarizing negative or hyperpolarizing

11 Sensory receptor cells Some sensory receptor cells have axons and generate action potentials Other cells do not generate action potentials

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14 Scanning electron micrograph of the olfactory epithelium E. Morrison and R. Costanzo

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16 1 m Morrison and Costanzo 1990

17 Olfactory transduction takes place in the cilia

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27 How many odorant receptor genes? 1,000 genes

28 Nobel Prize in Physiology or Medicine 2004 for their discoveries of odorant receptors and the organization of the olfactory system Linda BuckRichard Axel

29 1000 recettori 350 recettori

30 How many type of odorant receptor per cell? 1 type only

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32 How are odorant receptors spatially expressed in the olfactory epithelium? Randomly in each of four zones

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36 How many odorant molecules can activate an olfactory sensory neuron ? One neuron can respond to many odorant molecules

37 One type of odorant molecule: how many types of odorant receptors can activate? One type of odorant molecule can activate many types of odorant receptors

38 PERA BANANA

39 Denis

40 A P B NO C D U G I R FP DAIN PUF PORD BUAP NAU BNIC

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42 From olfactory epithelium to olfactory bulb Representation of olfactory information

43 Mori et al., 1999 Zonal Organization in the Olfactory System

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47 GLOMERULI Un certo odore attiva una definita combinazione di glomeruli

48 NASOBULBO

49 Information coding in the olfactory cortex

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52 BulbEpithelium Cortex

53 NASOBULBOCORTECCIA

54 Olfactory transduction cAMP is the main second messenger

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59 Ca concentration increases in the cilia and has a dual effect 1- excitatory 2- inhibitory

60 Ca excitatory effect: direct activation of Cl current In situ Cl gradient measurements (rat, mucus/knob concentrations) [Cl-]i = 69 mM [Cl-]o = 55 mM E cl = +6mV (Reuter et al.)

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64 Adaptation

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68 Adaptation adjusts the dynamic range of the response to allow the sensory cell to respond to changes in odor concentration over a wide range.

69 Mechanism of adaptation Intracellular Calcium concentration controls adaptation acting on the transduction cascade

70 Transduction in an olfactory sensory neuron

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72 Caged compound Uncaged: physiologically active

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85 8-Bromo-cAMP 1- is resistant to hydrolysis by PDE 2- activates cAMP-gated channels with higher affinity than cAMP

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93 Transduction in an olfactory sensory neuron

94 S.I.S.S.A. Trieste

95 Collaborators C.N.R. Genova Cristiana Picco Paola Gavazzo S.I.S.S.A. Trieste Laura Lagostena Anna Boccaccio Andrea Mazzatenta Giulietta Pinato Simone Pifferi Ranken Shimazaki Japan Takashi Kurahashi Germany Benjamin Kaupp USA Stuart Firestein Peter Mombaerts


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