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Department of Cell Biology Faculty
Mimi Halpern, Ph.D.
Department of Cell Biology, Box 5
Tel: (718) 270-2416 • Fax: (718) 270-3732
Biology of Nasal Chemical Senses
Most terrestrial vertebrates possess several nasal chemoreceptive systems including the olfactory and vomeronasal systems. The major focus of interest in this laboratory is to understand the structure and functional significance of the vomeronasal (VN) system and to contrast it to the main olfactory system (MOS). Among our early contributions was the demonstration of the dynamic nature of the snake's VN epithelium and its capacity for regeneration following degeneration.
Our behavioral studies have demonstrated the critical importance of the garter snake VN system in prey attack, prey extract attack, prey extract trailing, aggregation and male courtship of attractive females. We have also demonstrated that stimulation of the VN system is intrinsically rewarding to snakes. At this time we are investigating the role of the various brain structures that form part of the circuitry for tongue flicking on tongue response to chemical stimuli.
One of the central concerns in chemosensory science is understanding the mechanism of sensory transduction. The bias, at present, is to look for receptor proteins on membranes of receptor cells. We have isolated and characterized a number of proteins from prey (earthworm) products that are vomeronasally mediated chemoattractants for snakes. Among these proteins is a 20 kDa glycoprotein that binds specifically to VN receptor membranes and induces changes in second messenger systems in VN receptor cells.The major second messenger system used by the vomeronasal receptor cells of snakes is inositol 1,4,5-trisphosphate. Currently we are investigating the role of calcium release in the signal transduction process.
Electrophysiological studies have, using single unit extracellular recording from mitral cells in the accessory olfactory bulb or main olfactory bulb, demonstrated that prey extracts delivered to the VN epithelium as liquids activate the VN system, but similar extracts delivered as air streams do not. Conversely, prey extracts delivered as air streams to the MO epithelium activate the MOS, but similar extracts delivered as liquids do not.
We have studied the development and organization of the VNS in the South American grey short-tailed opossum, Monodelphis domestica. The accessory olfactory bulb is heterogeneous with respect to a number of markers and it appears that the receptor cells in the VN epithelium are similarly heterogeneous. We have found that there are at least two parallel VN pathways from periphery to the brain, and that these parallel pathways extend more centrally into the amygdala. We are now studying the functional correlates of these parallel pathways.
SELECTED RECENT PUBLICATIONS
1. Halpern, M. The organization and function of the vomeronasal system. Annual Review of Neuroscience. 10: 325-362, 1987.
2. Jiang, X. C., J. Inouchi, D. Wang and M. Halpern. Purification and characterization of a chemoattractant from earthworm electric shock-induced secretion, its receptor binding, and signal transduction through the vomeronasal system of garter snakes. Journal of Biological Chemistry. 265:8736-8744, 1990.
3. Luo, Y., Lu, S., Chen, P., Wang, D. and Halpern, M. Identification of chemoattractant receptors and G proteins in the vomeronasal system of garter snakes. Journal of Biological Chemistry, 269:16867-16877, 1994.e
4. Halpern, M., Shapiro, L. S. and Jia, C-P. Differential localization of G proteins in the opossum vomeronasal system. Brain Research, 677:157-161, 1995.
5. Jia, C. and Halpern, M. Subclasses of vomeronasal receptor neurons: differential expression of G proteins (Gia2 and Goa) and segregated projections to the accessory olfactory bulb. Brain Research, 719:117-128, 1996.
6. Martínez-Marcos, A Ubeda-Bañón, I. and Halpern, M. Neural substrates for tongue-flicking behavior in snakes Journal of Comparative Neurology 432:75-87, 2001.
7. Cinelli, A.R. Wang, D., Chen, P., Liu, W., Halpern, M. Calcium transients in the garter snake vomeronasal organ. Journal of Neurophysiology, 87:1449-1472, 2002.
8. Halpern, M. and Martinez-Marcos, A. Structure and function of the vomeronasal system: an update. Progress in Neurobiology, 70, 245-318, 2003.
9. Martinez-Marcos, A., Ubeda-Banon, I., Lanuza, E. and Halpern, M. The olfactostriatum: a key structure for processing vomeronasal information in snakes. Chemoarchitecture and afferent connections. J. Chemical Neuroanatomy, 29:49-69, 2005.
10. Zuri, I., Dombrowski, K. and Halpern, M. Skin and gland but not urine odours elicit conspicuous investigation by female gray short-tailed opossums (Monodelphis domestica). Animal Behavior, 2005, 69, 635-642.