Leslie Tolbert
Professor of Neurobiology and Cell Biology and Anatomy
Ph. D., Harvard University, (1978), Postdoctoral Research- Harvard Medical School and Harvard University
Teaching Areas- Neurobiology
E-mail: tolbert@neurobio.arizona.edu
Research Interest:
Neuron-glia interactions in the developing olfactory system
Research in my laboratory focuses on intercellular interactions during neuronal development. We are especially interested in mechanisms underlying the strategic role played by sensory axons in guiding the development of their target areas in the brain. Using the insect olfactory system as a model system, we are exploring developmental interactions that influence cell shape and synaptic connections. We focus on the cellular events by which olfactory axons induce the formation of structures called "glomeruli", which appear in virtually all olfactory systems.
Our research over the past several years has indicated that glial cells are essential for the formation of glomeruli. The work has led us to hypothesize that glial cells act as intermediaries in the developmental influence that olfactory axons exert upon their targets, i.e. that glial cells are "transformed" by exposure to olfactory axons and that "transformed" glia form the scaffold within which olfactory sensory neurons and target neurons differentiate glomerular arbors.
Using confocal and electron microscopy, intracellular dye-injection, immunocytochemistry, autoradiography, biochemical assays, and molecular biological techniques, we currently are testing our hypothesis both in the brain and with cells dissociated from the brain and grown in culture. For example, we are exploring the nature of the signal from olfactory axons, how stable the "transformation" of glia is, whether the "transformation" involves the expression of cell-surface and/or extracellular-matrix-bound molecules, and how such molecules influence growing neurites.
In the long run, we hope to understand the influences of sensory axons on their developing targets at a molecular level. We expect that the knowledge we gain will offer insights into intercellular influences in less accessible developing mammalian systems. In other, collaborative, lines of research, we are asking: What is the functional role of glomeruli, so characteristic of olfactory systems? With Dr. Mark Willis, we are performing behavioral tests of olfactory function in moths whose brains lack olfactory glomeruli (due to surgical manipulation during development) to determine whether glomerular organization of synapses is necessary for detection of odors, sensitivity to odors, and discrimination among odors. With Dr. Alwyn Scott, we are constructing mathematical models of glomerular and aglomerular neuropils to explore the impact of glomerular organization on information processing capabilities of olfactory neurons.
Selected Publications:
Wegerhoff R, W Rössler, MR Higgins, LA Oland, LP Tolbert (2001) Fenvalerate treatment affects development of olfactory glomeruli in Manduca sexta. J. Comp. Neurol. 430:533-541
Rössler W, Tolbert LP, Hildebrand JG (2000) Importance of timing of olfactory receptor-axon outgrowth for glomerulus development in Manduca sexta. J. Comp. Neurol. 425:233-243
Burd GD, Tolbert LP (2000) Development of the Olfactory System. In Neurobiology of Taste and Smell, TE Finger, WL Silver, and D Restreppo (eds.), John Wiley and Sons, pp. 233-255
Rössler W, Oland LA, Higgins MR, Hildebrand JG, Tolbert LP (1999) Development of a glia-rich axon-sorting zone in the olfactory pathway of the moth Manduca sexta. J. Neurosci. 19:9865-9877
Rössler W, Randolph PW, Tolbert LP, Hildebrand JG (1999) Axons of olfactory receptor cells of trans-sexually grafted antennae induce development of sexually dimorphic glomeruli in Manduca sexta. J. Neurobiol. 38:521-541
Oland LA, LP Tolbert (1998) Glomerulus development in the absence of a set of mitral-like neurons in the insect olfactory lobe. J. Neurobiol. 36:41-52
Oland LA, WM Pott, MR Higgins, LP Tolbert (1998) Targeted ingrowth and axon-glial relationships of olfactory receptor axons in the primary olfactory pathway of an insect. J. Comp. Neurol. 398:119-138
Rössler W, Tolbert LP, Hildebrand JG (1998) Early formation of sexually dimorphic glomeruli in the developing olfactory lobe of the brain of the moth Manduca sexta. J. Comp. Neurol. 396:415-428
Sun XJ, LP Tolbert, JG Hildebrand, IA Meinertzhagen (1998) A rapid method for combined laser scanning confocal microscopic and electron microscopic visualization of biocytin or neurobiotin-labeled neurons. J. Histochem. Cytochem. 46:263-273
Edwards JS, Tolbert LP (1998) Chapter 19: Insect Neuroglia. In Microscopic Anatomy of the Invertebrates, M. Locke (ed.), Wiley-Liss Inc.,Vol 11B: Insecta, pp. 449-466
Tolbert LP (1998) Olfactory development in invertebrates: on the scent of central developmental issues. In "Olfaction and Taste XII: An International Symposium," Annals NY Acad. Sci. 855:95-103
