Some people lie awake at night contemplating relationships, worrying about their jobs, or stressing over schoolwork. Bob Lane, professor of Molecular Biology and Biochemistry, wonders how we smell.
More specifically, Lane wonders how it is that each of the sensory neurons in our noses detects one and only one type of molecule, at the exclusion of all others. The National Science Foundation (NSF) recently awarded Lane a research grant for just under $300,000 to work on this very problem.
A specialist in molecular biology, Lane did his postdoctoral work with Dr. Leroy Hood, one of the “founding fathers” of the Human Genome Project, which mapped the genes in our DNA. But the nitty-gritty work of identifying genes in human DNA is not what interests Lane—he’s interested in what lies between the genes.
“A very large fraction of the genome, that nobody talks about, are sequences that don’t code genes, but sit next to genes and dictate when and where and how much of a gene is expressed in a given context,” Lane said.
These so-called regulatory sequences are what interest Lane, which then brought him to the olfactory system—our sense of smell—marking a surprising frontier in genome research.
Our nose contains millions of neurons, each one capable of detecting only one type of molecule. We sense smells when molecules in the air react with proteins at the ends of these neurons, which then send signals to our brain.
The question for Lane is this: of the thousand-or-so receptor-proteins in our genes that the neurons in our noses can express, how do our neurons select just one receptor-protein in which to specialize? Lane and other experts in the field have narrowed down the possibilities to two hypotheses. Both are relatively simple in concept but will almost certainly reveal whole new molecular mechanisms for how our genes are regulated or, in plain English, how our DNA works in our cells.
The first option is that when one gene with the code for one receptor-protein is expressed, all the other genes are suppressed through a complicated system of interacting genes. The second option Lane affectionately calls the “parking space model.”
“[There might be] some physical entity in the nucleus,” Lane said. “A novel entity that we hadn’t known about before…that is a unique space for one and only one gene to associate at a time.”
In other words, the parking space model theorizes that thousands of different smell genes are all competing for a single “parking space” in the nucleus of the olfactory neuron. Once a gene finds the parking spot, the neuron will specialize in detecting that gene’s smell.
Scientists have observed almost nothing like either of these options in nature before.
“There is little or no biological precedent in terms of how this system is orchestrated,” Lane said.
To determine which of these two options is correct, Lane and his team are fusing together cells that have already settled on what type of molecule they detect. If the first model is correct, then only one of the two proteins should be expressed once the cells are fused, because one of the genes will tell the other one to stop expressing itself. If the parking space model is correct, then the two genes should ignore each other and the fused cell should express both of their settled-upon genes, because the fused cell will have two nuclei and two parking spaces, one from each cell.
When Lane began research on the olfactory system 10 years ago the potential for new discovery was exactly what he hoped for. At the outset, he had little interest in smell. Ironically, Lane has allergies and can’t smell very well, though when pressed he decided on apple pie as his favorite smell. He warns against thinking of the study of our sense of smell as vain and unnecessary, since we tend treat it more as an aesthetic sense than a primal one.
“I might have thought, naively perhaps, that studying olfaction is a luxurious pursuit and not really of great medical import,” Lane said. “But this system will teach us a number of things, both in terms of molecular biology, such as how genomes and complex gene families are regulated, and neurobiology, such as how sensory information from the environment is processed into perception. It’s an extremely complex and interesting system.”
Molecular Biologist Lane Wins Grant for Olfactory Research
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Humans have the most scent glands, as well as the most active scent glands, of any species.
Humans have the greatest receptor field of microvillar brush border cells –they line our upper respiratory system.
Humans have more of our brains lighting up on pheromone exposure than any other species, as well.Pheromones have cured criminal behavior, drug addiction, even sexual perversions. See:
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