Neuroligins belong to a highly conserved family of cell adhesion molecules that have been implicated in synapse formation and function. However, the precise in vivo roles of Neuroligins remain unclear. In the present study, we have analyzed the function of Drosophila neuroligin 2 (dnl2) in synaptic development and function. We show that dnl2 is strongly expressed in the embryonic and larval CNS and at the larval neuromuscular junction (NMJ). dnl2 null mutants are viable but display numerous structural defects at the NMJ, including reduced axonal branching and fewer synaptic boutons. dnl2 mutants also show an increase in the number of active zones per bouton but a decrease in the thickness of the subsynaptic reticulum and length of postsynaptic densities. dnl2 mutants also exhibit a decrease in the total glutamate receptor density and a shift in the subunit composition of glutamate receptors in favor of GluRIIA complexes. In addition to the observed defects in synaptic morphology, we also find that dnl2 mutants show increased transmitter release and altered kinetics of stimulus-evoked transmitter release. Importantly, the defects in presynaptic structure, receptor density, and synaptic transmission can be rescued by postsynaptic expression of dnl2. Finally, we show that dnl2 colocalizes and binds to Drosophila neurexin (dnrx) in vivo. However, whereas homozygous mutants for either dnl2 or dnrx are viable, double mutants are lethal and display more severe defects in synaptic morphology. Altogether, our data show that, although dnl2 is not absolutely required for synaptogenesis, it is required postsynaptically for synapse maturation and function.

He C., Wei Y. D. and Xie X. Globalization, institutional change, and industrial location: economic transition and industrial concentration in China, Regional Studies. Marketization and globalization in China may stimulate industrial clustering, while decentralization may lead to protectionism and industrial dispersion. This paper examines industrial distribution in China during 1980-2003. While Chinese industries have been increasingly concentrated geographically, the study found significant temporal and sectoral variations in concentration. Least protected industries have become increasingly concentrated, and most globalized industries are clustered in the coastal region. The analysis indicates that globalization and internal scale economies have contributed to geographical concentration, while protectionism has hindered industrial specialization. While industries are more likely to locate based on comparative advantages, external scale economies have not fostered industrial concentration. [image omitted] He C., Wei Y. D. et Xie X. La mondialisation, la transformation institutionnelle, et la localisation industrielle: la mutation economique et la concentration industrielle en Chine, Regional Studies. Il se peut que la commercialisation et la mondialisation en Chine encouragent l'etablissement de grappes industrielles, alors que la decentralisation amene au protectionnisme et a la dispersion industrielle. Cet article cherche a examiner la distribution industrielle en Chine entre 1980 et 2003. Tandis que l'industrie chinoise se concentre de plus en plus, il s'avere que cette concentration varie sensiblement des points de vue temporel et sectoriel. L'industrie la moins protegee se concentre de plus en plus et l'industrie la plus mondialisee s'agglomere pour la plupart dans la zone cotiere. L'analyse laisse voir que la mondialisation et les economies d'echelle internes ont contribue a la concentration geographique, alors que le protectionnisme a entrave la specialisation industrielle. Pendant que l'industrie se localise en fonction de l'avantage comparatif, les economies d'echelle externes n'encouragent pas la concentration industrielle. Mutation economique Mondialisation Decentralisation Agglomeration Concentration geographique Chine He C., Wei Y. D. und Xie X. Globalisierung, institutioneller Wandel und Industriestandorte: wirtschaftlicher Wandel und industrielle Konzentration in China, Regional Studies. Die Marktorientierung und Globalisierung in China kann sich fordernd auf die industrielle Clusterbildung auswirken, wahrend eine Dezentralisierung zu Protektionismus und industrieller Streuung fuhren kann. In diesem Beitrag untersuchen wir die industrielle Verteilung in China im Zeitraum von 1980 bis 2003. Die chinesischen Industrien haben sich geografisch zunehmend konzentriert, doch zugleich finden wir signifikante zeitliche und sektorale Schwankungen hinsichtlich der Konzentration. Die am wenigsten geschutzten Industrien haben sich zunehmend konzentriert, wahrend die am starksten globalisierten Industrien in Cl...

The idea that skills, technology, and knowledge, are spatially concentrated, has a long academic tradition. Yet, only recently this hypothesis has been empirically formalized and corroborated at multiple spatial scales, for different economic activities, and for a diversity of institutional regimes. The new synthesis is an empirical principle describing the probability that a region enters-or exits-an economic activity as a function of the number of related activities present in that location. In this paper we summarize some of the recent empirical evidence that has generalized the principle of relatedness to a fact describing the entry and exit of products, industries, occupations, and technologies, at the national, regional, and metropolitan scales. We conclude by describing some of the policy implications and future avenues of research implied by this robust empirical principle. C. A. Hidalgo and P.-A. Balland-Contributed equally.

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