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This paper discusses the evolution of scientific and social understanding that has led to the development of knowledge systems supporting the application of El Niño-Southern Oscillation (ENSO) forecasts, including the development of successful efforts to connect climate predictions with sectoral applications and actions "on the ground". The evolution of "boundary-spanning" activities to connect science and decisionmaking is then discussed, setting the stage for a report of outcomes from an international workshop comprised of producers, translators, and users of climate predictions. The workshop, which focused on identifying critical boundary-spanning features of successful boundary organizations, included participants from Australia, Hawaii, and the Pacific Islands, the US Pacific Northwest, and the state of Ceará in northwestern Brazil. Workshop participants agreed that boundary organizations have multiple roles including those of information broker, convenor of forums for engagement, translator of scientific information, arbiter of access to knowledge, and exemplar of adaptive behavior. Through these roles, boundary organizations will ensure the stability of the knowledge system in a changing political, economic, and climatic context. The international examples reviewed in this workshop demonstrated an interesting case of convergent evolution, where organizations that were very different in origin evolved toward similar structures and individuals engaged in them had similar experiences to share. These examples provide evidence that boundary organizations and boundary-spanners fill some social/institutional roles that are independent of culture.

Two molecular processes, the binding of acetylcholine to the membrane-bound acetylcholine receptor protein and the receptor-controlled flux rates of specific inorganic ions, are essential in determining the electrical membrane potential of nerve and muscle cells. The measurements reported establish the relationship between the two processes: the acetylcholine receptor-controlled transmembrane ion flux of (86)Rb(+) and the concentration of carbamoylcholine, a stable analog of acetylcholine. A 200-fold concentration range of carbamoylcholine was used. The flux was measured in the millisecond-to-minute time region by using a quench flow technique with membrane vesicles prepared from the electric organ of Electrophorus electricus in eel Ringer's solution at pH 7.0 and 1 degrees C. The technique makes possible the study of the transmembrane transport of specific ions, with variable known internal and external ion concentrations, in a system in which a determinable number of receptors is exposed to a known concentration of ligand. The response curve of ion flux to ligand was sigmoidal with an average maximum rate of 84 sec(-1). Carbamoylcholine induced inactivation of the receptor with a maximum rate of 2.7 sec(-1) and a different ligand dependence so that it was fast relative to ion flux at low ligand concentration but slow relative to ion flux at high ligand concentration. The simplest model that fits the data consists of receptor in the active and inactive states in ligand-controlled equilibria. Receptor inactivation occurs with one or two ligand molecules bound. For channel opening, two ligand molecules bound to the active state are required, and cooperativity results from the channel opening process itself. With carbamoylcholine, apparently, the equilibrium position for the channel opening step is only one-fourth open. The integrated rate equation, based on the model, predicts the time dependence of receptor-controlled ion flux over the concentration range of carbamoylcholine investigated. The values of the constants in the rate equation form the basis for predicting receptor-controlled changes in the transmembrane potential of cells and the conditions leading to transmission of signals between cells.