1. L'alfabeto
degli odori

2. L’alfabeto degli odori
Anna Menini
Neurobiology Sector
International School for Advanced Studies
Trieste, Italy

5. Common Odor Compounds alkanes Halides aldehydes amine alcohols
formiates X O H
alcohols C
carboxylic acids R
aldehydes
ketones
esters OR
alkanes X C N
cyanide S H
thiol 2
amine B r
Halides

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. How many mechanisms of transduction?Na
Ca2+
1- IONOTROPIC
2- METABOTROPIC
molecules
Light
Na+
Ca2+ l R G C

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

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

16. 1mm
Morrison and Costanzo 1990

17. Olfactory transduction takes place in the cilia

27. How many odorant receptor genes?

28. Nobel Prize in Physiology or Medicine 2004
Linda Buck
Richard Axel
“for their discoveries of odorant receptors and the organization of the olfactory system”

29. 350 recettori
1000 recettori

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

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

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. Denis A N D I P U F P O D R A B U P A N U B N C I A P B N O C D U G I

42. From olfactory epithelium to olfactory bulb
Representation of olfactory information

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

47. Un certo odore attiva una definita combinazione di glomeruli

48. NASO
BULBO

49. Information coding in the olfactory cortex

52. Epithelium
Bulb
Cortex

53. NASO
BULBO
CORTECCIA

54. Olfactory transduction cAMP is the main second messenger

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 Ecl = +6mV (Reuter et al.)

64. Adaptation

68. Adaptation
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

72. Caged compound
Uncaged:
physiologically
active

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

93. Transduction in an olfactory sensory neuron

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

95. Collaborators Japan Takashi Kurahashi Germany Benjamin Kaupp USA
Stuart Firestein
Peter Mombaerts
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