Courtesy of The Institute of Molecular Pathology

A team of scientists from the University of California, Riverside and Stanford University uncovered how different sensory neurons function in the olfactory system through Drosophila, a genus of small flies.

“One of the biggest mysteries is how the brain works. Almost every neuron in the brain is unique in the way it connects to others and responds to signals,” stated Dr. Anandasankar Ray, assistant professor of entomology at UCR and head of the research team.

Ray and his researchers identified the large multi-protein complex, MMB/dREAM, which play a key role in the selection and expression of carbon dioxide receptors in appropriate neurons.

The olfactory system senses volatile chemicals in the environment very efficiently, explained Ray. For most animals, the chemical signals help the brain make important daily decisions in eating habits, fight-or-flight and mating behavior. Due to such a wide variety of volatile chemicals, the nose has developed a large array of sensors to detect them. These large array sensory neurons each express a single odor receptor protein.

“Our research investigates how the one receptor-per neuron pattern is generated with precision. We show using the model genetic system Drosophila (fruit fly), that most odor receptors are kept in an “off” state by an ancient molecular machinery that represses gene expression,” stated Ray.

A single receptor gene is selected to be turned “on” in a particular neuron. In different neurons specific odor receptor genes are turned on for expression, thus generating the differentiated pattern. For example, when a person smells an orange, the brain recognizes the scent of an orange because the nose has a specific odor receptor that detects a chemical the orange emits.

“I am interested in understanding basic mechanisms that underlay the generation of neuronal diversity in the nervous system,” Ray said.

The research project started about a year and a half ago, when Stanford Ph.D student Choon Kiat Sim contacted Dr. Ray with the potential project. Sim is a disciple of Stanford professor Joseph S. Lipsick, who also collaborated with her on the project, along with UCR graduate Serra Perry, as the first co-authors of the research paper. Both of them were supported by Sara Tharadra, a junior researcher in Ray’s lab.

A grant given to Ray by the Whitehall Foundation was used to fund the research project. The study was a cover-page feature in the Nov.15 issue of Genes & Development, a scientific journal containing biological and molecular research.