Coalition governance and foreign policy decision making

This article explores processes of coalition governance in foreign policy. Specifically, it argues that such processes are shaped by two interrelated dimensions of coalition set-up: first, the allocation of the foreign ministry to the senior or a junior coalition partner and, second, the degree of policy discretion which is delegated to that ministry. Bringing these two dimensions together, the article distinguishes four types of coalition arrangement for the making of foreign policy, which are expected to have predictable implications for the process of foreign policy-making and, ultimately, for the foreign policy outputs of multi-party coalitions and their quality

Time-Lapse Analysis and Mathematical Characterization Elucidate Novel Mechanisms Underlying Muscle Morphogenesis

Skeletal muscle morphogenesis transforms short muscle precursor cells into long, multinucleate myotubes that anchor to tendons via the myotendinous junction (MTJ). In vertebrates, a great deal is known about muscle specification as well as how somitic cells, as a cohort, generate the early myotome. However, the cellular mechanisms that generate long muscle fibers from short cells and the molecular factors that limit elongation are unknown. We show that zebrafish fast muscle fiber morphogenesis consists of three discrete phases: short precursor cells, intercalation/elongation, and boundary capture/myotube formation. In the first phase, cells exhibit randomly directed protrusive activity. The second phase, intercalation/elongation, proceeds via a two-step process: protrusion extension and filling. This repetition of protrusion extension and filling continues until both the anterior and posterior ends of the muscle fiber reach the MTJ. Finally, both ends of the muscle fiber anchor to the MTJ (boundary capture) and undergo further morphogenetic changes as they adopt the stereotypical, cylindrical shape of myotubes. We find that the basement membrane protein laminin is required for efficient elongation, proper fiber orientation, and boundary capture. These early muscle defects in the absence of either lamininβ1 or lamininγ1 contrast with later dystrophic phenotypes in lamininα2 mutant embryos, indicating discrete roles for different laminin chains during early muscle development. Surprisingly, genetic mosaic analysis suggests that boundary capture is a cell-autonomous phenomenon. Taken together, our results define three phases of muscle fiber morphogenesis and show that the critical second phase of elongation proceeds by a repetitive process of protrusion extension and protrusion filling. Furthermore, we show that laminin is a novel and critical molecular cue mediating fiber orientation and limiting muscle cell length

Expanding the Paradigms of Plant Pathogen Life History and Evolution of Parasitic Fitness beyond Agricultural Boundaries

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Current perspectives of the signaling pathways directing neural crest induction

The neural crest is a migratory population of embryonic cells with a tremendous potential to differentiate and contribute to nearly every organ system in the adult body. Over the past two decades, an incredible amount of research has given us a reasonable understanding of how these cells are generated. Neural crest induction involves the combinatorial input of multiple signaling pathways and transcription factors, and is thought to occur in two phases from gastrulation to neurulation. In the first phase, FGF and Wnt signaling induce NC progenitors at the border of the neural plate, activating the expression of members of the Msx, Pax, and Zic families, among others. In the second phase, BMP, Wnt, and Notch signaling maintain these progenitors and bring about the expression of definitive NC markers including Snail2, FoxD3, and Sox9/10. In recent years, additional signaling molecules and modulators of these pathways have been uncovered, creating an increasingly complex regulatory network. In this work, we provide a comprehensive review of the major signaling pathways that participate in neural crest induction, with a focus on recent developments and current perspectives. We provide a simplified model of early neural crest development and stress similarities and differences between four major model organisms: Xenopus, chick, zebrafish, and mouse

Host groups of Potato virus Y: vanishing barriers

Host groups of Potato virus Y: vanishing barrier

Evolution and Origin of PVY

International audienceThe mechanisms by which Potato virus Y variants are generated and selected are still unclear. Spontaneous mutations generated by uncorrected replication error and recombination events between viral isolates during co-infection of plant cells are the main likely source of genetic diversity. This high level of diversity generation is essential for virus evolution and survival in different environments. Different PVY strain groups have appeared over time: firstly, non-recombinant PVYC, PVYO and PVYN strains and, more recently, recombinant PVYN-Wi and PVYNTN strains with novel biological characteristics and the ability to cause potato tuber necrotic ringspot disease (PTNRD). Increased fitness of the recombinant strains appears to have enabled them to replace the non-recombinant variants in most potato growing areas of the world. Partial sequencing of PVY genome (P1, HC-Pro, CP, recombinant junctions) and whole genome sequencing has shown that non-recombinant and recombinant variants are present in potatoes and other plant hosts. Phylogenetic analyses have been applied to document changes in viral isolates and to establish the relationships between different viral isolates. Traditional phylogenetic analysis was, however, developed for bifurcating phylogenies and not for analysing recombination, as a result of which this presents challenges to these analyses which will be outlined in this chapter. The ongoing worldwide studies on PVY characterisation suggest that new variants with distinct biological properties are likely to be uncovered in the future. Emerging technologies such as next generation sequencing will provide valuable insights into PVY population dynamics and evolution in future