Leonard J. Kass
Associate Professor of Biological Sciences
Neurophysiology of sensory and motor systems; biological rhythms; cellular neurobiology of vision; gene expression in frog oocytes
This laboratory is generally concerned with understanding the workings of the brain and nervous system. The specific areas of research investigate the visual system and biological rhythms. Vision is explored by using the latest methodological techniques for whole-cell (WCR) and single channel voltage-clamp recordings from single isolated photoreceptors. These methods are applied to the classical preparation of Limulus ventral photoreceptor because of many special attributes: they are large, isolated, robust, exhibit unitary quantal bumps, and are dramatically altered by a circadian clock in the animal’s brain. Currently, recording or pharmacologically blocking specific membrane channels is leading to an understanding of photoreceptor function. Cellular mechanisms are further explored by injecting into these photoreceptors specific biochemical agents that inhibit or stimulate G-proteins, Calmodulin, Calcineurin, cAMP, cGMP, IP3, phosphatases, and various kinases. In short, these studies, along with collaborations with labs outside the state, are leading to a complete neurophysiological and biochemical understanding of cell function, and the role of the photoreceptor in an animal’s behavior. Mathematical modelling of photoreceptor kinetics is currently being pursued through a collaborative venture with the Math Department.
Other areas of research involve standard recording, staining, and tracing the pathways of neurons in the central nervous system of Limulus, especially those cells involved in the visual pathway or part of the biological clock circuitry. This laboratory is one of several around the world whose ultimate goal is to understand animal behavior starting at the origin of vision (i.e., the photorecptor cell) and proceeding into the brain (neurocircuitry and pathways) and ultimately to changes in behavior, as studied in the lab and in the field.
Kass, L., D.Z. Ellis, J. Pelletier, N.E. Tableman, and S.C. Edwards (1998) Inhibition of the calcineurin-like phospatase activity in Limulus ventral eye photoreceptor cells alters the characteristics of the spontaneous quantal bumps and the light-mediated inward currents, and enhances arrestin phosphorylation. Visual Neuroscience 15: 1039-1049.
Wharten, D.N., R.N. Jinks, B.-A. Battelle, E.D. Herzog, L. Kass, G.H. Renninger and S.C. Chamberlain. (1997) Morphology of the eye of the hydrothermal vent shrimp, Alvinocaris markensis. Journal of Marine Biological Association U.K. 77:1097-1108.
Lakin, R.C., R.N. Jinks, B.-A. Battelle, E.D. Herzog, L. Kass, G.H. Renninger and S.C. Chamberlain. (1997) Retinal anatomy of Chorocharis chacei, a deep-sea hydrothermal vent shrinp from the Mid-Atlantic Ridge. Journal Comparative Neurology. 384.
Gaus, G., M. Casaretto, and L. Kass (1997) The effect of neuropeptides from Limulus on its circadian rhythm in retinal sensitivity. Journal of Comparative Physiology A. 180:137-142.
Kass, L. and W.O. Bray (1996) Kinetic model for phototransduction and G-Protein enzyme cascade: Understanding quantal bumps during inhibition of CaM-KII or PP2B. Journal of Photochemistry and Photobiology B. 35:105-113.
Zhang, H.-j., Jinks, R.N., Wishart, A.C., Battelle, B.-a., Chamberlain, S.C., Fahrenbach, W.H. and Kass, L. 1994. An enzymatically enhanced recording technique for Limulus ventral photoreceptors: Physiology, biochemistry, and morphology. Visual Neuroscience. 11: 41-52.
Kass, L. and Barlow, Jr. R.B. 1992. A circadian clock in the Limulus brain transmits synchronous efferent signals to all eyes. Visual Neuroscience. 9: 493-504.
Powers, M.K., Barlow, Jr. R.B. and Kass, L. 1991. Visual performance of horseshoe crabs day and night. Visual Neuroscience. 7: 179-189.