Development and Notch Signaling Requirements of the Zebrafish Choroid Plexus

The choroid plexus (CP) is an epithelial and vascular structure in the ventricular system of the brain that is a critical part of the blood-brain barrier. The CP has two primary functions, 1) to produce and regulate components of the cerebral spinal fluid, and 2) to inhibit entry into the brain of exogenous substances. Despite its importance in neurobiology, little is known about how this structure forms.Here we show that the transposon-mediated enhancer trap zebrafish line Et(Mn16) expresses green fluorescent protein within a population of cells that migrate toward the midline and coalesce to form the definitive CP. We further demonstrate the development of the integral vascular network of the definitive CP. Utilizing pharmacologic pan-notch inhibition and specific morpholino-mediated knockdown, we demonstrate a requirement for Notch signaling in choroid plexus development. We identify three Notch signaling pathway members as mediating this effect, notch1b, deltaA, and deltaD.This work is the first to identify the zebrafish choroid plexus and to characterize its epithelial and vasculature integration. This study, in the context of other comparative anatomical studies, strongly indicates a conserved mechanism for development of the CP. Finally, we characterize a requirement for Notch signaling in the developing CP. This establishes the zebrafish CP as an important new system for the determination of key signaling pathways in the formation of this essential component of the vertebrate brain

A model for cooperative transportation scheduling

The Mars system is described which models cooperative scheduling within a society of shipping companies as a multiagent system. Emphasis is placed on the functionality of the system as a whole--- the solution of the global scheduling problem emerges from local decision-making and problem-solving strategies. An extension of the contract net protocol is presented; we show that it can be used to obtain good initial solutions for complex resource allocation problems. By introducing global information based upon auction protocols, this initial solution can be improved significantly. Experimental results are provided evaluating the performance of different cooperative scheduling strategies. Although the concepts for resource scheduling are presented solely for the transportation domain, their abstraction is useful for a broad variety of resource allocation problems. The Mars system solves the dynamic scheduling problem where no complete specification of the problem is available a priori; thus, it is designed as an on-line system based upon anytime algorithms