Page 120 - The Miracles of Smell and Taste

118

zation. The olfactory neuron is uniquely suited for these studies since it
is designed specifically for the detection and discrimination of a wide
variety of small organic molecules, i.e. odors.

The most recent work in the lab utilizes Adenovirus vectors to drive
over-expression of cloned odor receptors in olfactory neurons. Because
odor receptors make up the largest family of G-protein coupled recep-
tors (also including many neurotransmitter ands hormone receptors)
they are excellent receptors to try and understand the relation between
amino acid sequence and ligand binding affinities. We are able to over
express particular receptors as well as receptor clones with targeted mu-
tations and then screen these for specific ligand sensitivities. These data
are then included in computer models of the protein receptor to under-
stand precisely why one receptor is able to recognize the odor of say, ro-
ses, while another is specific for pizza.
In another vein, olfactory receptors are unique among neurons for the
ability to regenerate throughout an animal’s life. Several experimental
manipulations have been developed to induce neuronal regeneration
and proliferation in vivo allowing one to harvest neurons with a known
date of birth. By applying physiological techniques for cell recording we
are quantifying biophysical parameters, such as the appearance of ion
channels or receptors and the development of synaptic contacts, in de-
veloping neurons. 102

From all his statements, only one meaning can be extracted: Very lit-
tle is actually known about the sense of smell, even at the science’s pre-
sent advanced level. The conclusion from all the resources that have been
mobilized and the research carried out is that much of what is known is
still theoretical. What’s known, however, is the magnificent structure of
the olfactory system. Indeed, Stuart Firestein draws attention to this in the
abstract section of his paper:

The Miracles of Smell and
Taste