This proposal is submitted for funding the purchase of a tabletop ultracentrifuge. This type of centrifuge is particularly useful for the isolation of cellular fractions and purification of nucleic acid samples, where small volumes, high speed and short spin times are required. The instrument will be used in three major projects: (1) Membrane preparation: isolation and reconstitution of bacterial membrane fractions will be performed in the context of the electrophysiological study of Escherichia coli porins and other bacterial ion channels. (2) Isolation of RNA by cesium gradient centrifugation will be performed from embryonic explants in the context of the study of gene regulation during neural induction of Xenopus embryos. (3) RNA will be isolated by cesium gradient centrifugation from zebrafish pineal glands in studies of gene regulation by light and the circadian clock The productivity and success of our research efforts will be greatly enhanced by the acquisition of the proposed instrument, which will allow us to perform procedures that are not feasible with the present state of our instrumentation.