William M. Saidel - US grants

A class of large diameter afferent nerve fibers innervate the otolithic or otoconial organs, the saccule, utricle, and lagena (of non-mammals) and the three semicircular canal cristae in a spatially selective manner. Each of these nerve fibers innervate several sensory hair cells. The physiological response of each fiber presumably results from combining inputs from all innervated hair cells, and physiological dogma presumes that each hair cell that synapses on an afferent fiber has roughly the same potential for influencing action potential generation of that fiber. By using a cytochemical cation-binding procedure that identifies the axonal locations where action potentials may be initiated, preliminary results suggest that an individual hair cell synapsing with these large diameter fibers may directly generate a regenerative potential if the post-synaptic potential produced is sufficiently large. Synapses of adjacent hair cells do not stain, suggesting that other pre-synaptic hair cells may not have the same capacity. Initiation of an action potential at the post-synaptic membrane would insure orthodromic conduction of hair cell responses through the intraepithelial internodal segment of the terminal to the axon proper. This proposal will study the cation binding of post-synaptic membrane in vestibular end-organs of fish, frogs, birds, and mammals. The questions to be considered are (1) the spatial distribution of cation binding post-synaptic membrane; (2) the phylogenic distribution of cation binding post-synaptic membrane in the saccule and utricle of the 4 vertebrate groups named previously; and (3) the relationship between the hair cells synapsing onto a single branch of an eighth nerve fiber and cation- binding post-synaptic membrane.

This award is funded by the Divisions of Biological Infrastructure and Chemistry at NSF. The REU Site program at Rutgers University Camden campus will provide research internship for ten undergraduate students for ten weeks each summer. The students will work in close collaboration with their faculty mentors on independent research projects relevant to the New Jersey Pinelands, and the students will have the opportunity in the first two weeks of the program to use the lab facilities and to reside at the Pinelands Field station. The NJ Pinelands is a unique ecosystem with approximately 1.1 million acres, which has been given International Biosphere status. The goal of the program is to provide biology and chemistry undergraduate students with the opportunity to experience cutting-edge research over a wide range of various disciplines (Biology, Chemistry and Physics) and emphases, in order to broaden students' perspectives on a research career in the sciences. This goal will be accomplished via interdisciplinary mentoring, the opportunity to work on independent research projects from experimental design to data collection and analysis, and via different workshops, for example, scientific writing for peer-reviewed journals, scientific ethics, women in sciences and environmental justice. Students who are admitted to the program will be supplied with a stipend, housing, meals and airfare. Under-represented minorities and students from colleges with limited research opportunities are particularly encouraged to apply. More information is available by contacting Heike Bucking at bucking@camden.rutgers.edu, or by visiting http://reu-pinelands.camden.rutgers.edu/index.html.