Chitin is an essential component of the fungal cell wall, providing rigidity and stability. Its degradation is mediated by chitinases and supposedly ensures the dynamic plasticity of the cell wall during growth and morphogenesis. Hence, chitinases should be particularly important for fungi with dramatic morphological changes, such as Ustilago maydis. This smut fungus switches from yeast to filamentous growth for plant infection, proliferates as a mycelium in planta, and forms teliospores for spreading. Here, we investigate the contribution of its four chitinolytic enzymes to the different morphological changes during the complete life cycle in a comprehensive study of deletion strains combined with biochemical and cell biological approaches. Interestingly, two chitinases act redundantly in cell separation during yeast growth. They mediate the degradation of remnant chitin in the fragmentation zone between mother and daughter cell. In contrast, even the complete lack of chitinolytic activity does not affect formation of the infectious filament, infection, biotrophic growth, or teliospore germination. Thus, unexpectedly we can exclude a major role for chitinolytic enzymes in morphogenesis or pathogenicity of U. maydis. Nevertheless, redundant activity of even two chitinases is essential for cell separation during saprophytic growth, possibly to improve nutrient access or spreading of yeast cells by wind or rain.

Social media platforms are increasingly being used by governments to foster user interaction. Particularly in cities with enhanced ICT infrastructures (i.e., Informational World Cities) and high internet penetration rates, social media platforms are valuable tools for reaching high numbers of citizens. This empirical investigation of 31 Informational World Cities will provide an overview of social media services used for governmental purposes, of their popularity among governments, and of their usage intensity in broadcasting information online.

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Contemporary and future cities are often labeled as "smart cities, " "digital cities" or "ubiquitous cities," "knowledge cities," and "creative

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The purpose of this panel is to discuss actual developments in the co-creation of public services and the role of information science within it. With the advent of the knowledge society, participation and co-creation of public services have become crucial in smart-city decision-making processes. Transfer of knowledge through face-to-face interaction and the transfer of information through digital networks are spurring the process of innovation. The combination of both dimensions needs particular attention in the field of information science to enable suitable methods of knowledge management at a city level. This panel will bring together best-practice examples and research frameworks. In real-world scenarios, citizens are involved in decision-making in the case of public library development. First, frameworks of smart-city assessment and of knowledge management at the city level are discussed. Finally, the role of information science in open innovation processes will be the focus of this panel. For this purpose, the panel brings together researchers and practitioners from library and information science, as well as from neighboring disciplines, to discuss how information and communication technology (ICT) and open innovation are changing our society, culture, and urban space.

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