This multifaceted project provides new knowledge of auditory mechanisms through studies of auditory sensory organs, using small mammals, chicks and bullfrogs. Immunocytochemical studies of neurotransmitters, neuromodulators, receptors and other markers in the cochlea are being continued. As an additional step to define biochemically active molecules in the inner ear we are making monoclonal antibodies to the chick cochlea. In collaboration with the Laboratory of Molecular Biology, BNP, DIR, NINCDS we are continuing a study of the molecular biology of genes involved in the regulation and synthesis of putative auditory nerve and auditory hair cell neurotransmitters. We have focused on the enzymes glutamate dehydrogenase and glutaminase and have recently characterized a cDNA molecule which partially encodes glutaminase.
We aim at identifying cDNA molecules that encode the complete sequence of glutamate dehydrogenase and of glutaminase. We have taken initial steps to study hereditary deafness in mice using molecular biology techniques. We are continuing our studies of motile mechanisms in auditory sensory cells. We have analyzed the fine structure and relationships between cytoplasmic and extracellular structural elements in the frog sacculus otolithic sensory epithelium. An overall architectural framework within which to consider the process of mechanical transduction of this organ is being proposed. Several studies of basic intracellular transport and cell motility mechanisms are in progress. We have purified and enzymatically characterized kinesin from adrenal medulla gland. Like brain kinesin, it is capable of translocating beads along microtubules and promoting the gliding of microtubules on the surface of glass at the rate of .5 mum/s. We have obtained soluble fractions from Nitella extracts that have an actin activated ATPase and that translocate actin filaments on the surface of glass at 20-60 Mum/s which is comparable to the rate of cytoplasmic streaming in these cells. This is the first time that such active translocator has been solubilized from organelles.
