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Picture of Mark J. Zoran

Mark J. Zoran Banner
Assistant Professor
Department of Biology | Texas A&M University

3258 TAMU
Biological Sciences Building West - Room 231
College Station, TX 77843-3258
Office: 979-845-8099
Lab: 979-862-2819
Fax: 979-845-2891
Email: zoran@bio.tamu.edu


Biography Banner
Mark Zoran joined the Department of Biology faculty at Texas A&M University in January of 1992. He is currently an Associate Professor of Biology and Neuroscience, the Graduate Advisor for the Department of Biology, and the Chair of the Interdisciplinary Faculty of Neuroscience. Mark graduated from DePue High School (Illinois) in 1975. He earned a B.A. in Biology (1979) from Augustana College, Illinois, and an M.S. in Biological Sciences (1981) from Illinois State University. In 1987, he received a Ph.D. in Zoology (Neurobiology) from Iowa State University.

Mark Zoran has studied the parental care behaviors of Cichlid fishes, the neural pathways underlying rapid escape in aquatic oligochaetes, and the developmental mechanisms governing synapse formation between identified snail neurons. His current research interests include developmental relationships between electrical and chemical synapses in regenerating nervous systems, molecular mechanisms governing neural regeneration and morphallaxis, and the cellular control of physiological rhythms in the avian visual system (in collaboration with Dr. Vincent Cassone). Mark teaches undergraduate courses in physiology and neurobiology and graduate level courses in comparative neurobiology and neural development.

Cellular and Developmental Neuroscience Banner
My laboratory studies cellular mechanisms governing the formation of specific synaptic connections between neurons and their targets. These mechanisms include cell-cell recognition and target-dependent induction of the presynaptic secretion machinery. Our studies investigate synapse formation of identified motoneurons following nerve injury in vivo and following isolation of neurons into cell culture. Since the synapse is the site of most interneuronal communication within the nervous system, an understanding of the development, regeneration and plasticity of these connections is crucial to an ultimate appreciation of neural integration and brain function. In our studies of synaptic specificity, we take advantage of the accessibility of neurons within the buccal nervous system of the American pond snail, Helisoma trivolvis.

The central focus of my research program investigates the role of target-recognition and synaptic induction in the formation of neuromuscular synapses. Using electrophysiological techniques, we have found that identified buccal motoneurons are selective in synapse formation and require contact with appropriate muscle targets before acquiring secretory competence. Action potential-regulated transmitter release is elevated specifically at neuritic arbors in contact with appropriate muscle targets and not at contacts with inappropriate muscle targets. Image analyses of presynaptic neuronal architecture revealed that appropriate, but not novel, muscle targets elicit increased arborization of neurites at sites of contact. The long-term goal of these studies is to determine the signals and signaling mechanisms associated with this selective synaptogenesis. Blockage of activity-based cell-cell communication and inhibition of RNA and protein synthesis disrupt target-dependent induction of excitation-secretion coupling. Future studies will investigate the specific molecular machinery expressed during these crucial periods of synaptic contact. In addition, electrical synaptic connections are also formed by motoneurons in a robust, target-dependent fashion in cell culture. Therefore, another exciting direction my program has recently taken involves the cellular mechanisms governing specificity of electrical synaptogenesis.

Selected Publications
Zoran, M.J. and J.C. Poyer. 1998. Temporal and spacial resolution of Helisoma neuronal synapse formation. The Neuron in Cell Culture. IBRO Handbook (Ed. L.W. Haynes), John Wiley & Sons, Ltd., Sussex.

Achee, N.L. and M.J. Zoran. 1997. Serotonin-induced modulation of excitability in an identified Helisoma neuron. J. Exp. Biol. 200:1537-1548

Poyer, J.C. and M.J. Zoran. 1996. Activity-dependent induction of functional secretory properties at cultured neuromuscular synapses of Helisoma. J. Neurophysiol. 76:2635-2643

Zoran, M.J., B. Metts, and J.C. Poyer. 1996. Specific muscle contacts induce increased transmitter release and neuritic arborization in motoneuronal cultures. Dev. Biol. 179:212-222.

Achee, N.L. and M.J. Zoran. 1996. Short-term and long-term alterations in neuronal excitability during injury-induced axonal regeneration in ganglia and cell culture. Invet. Neurosci. 2:189-198.

 

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