Nephronectin regulates atrioventricular canal differentiation via Bmp4-Has2 signaling in zebrafish
Machteld J. van Amerongen
Felix B. Engel
- The extracellular matrix is crucial for organogenesis. It is a complex and dynamic component that regulates cell behavior by modulating the activity, bioavailability and presentation of growth factors to cell surface receptors. Here, we determined the role of the extracellular matrix protein Nephronectin (Npnt) in heart development using the zebrafish model system. The vertebrate heart is formed as a linear tube in which myocardium and endocardium are separated by a layer of extracellular matrix termed the cardiac jelly. During heart development, the cardiac jelly swells at the atrioventricular (AV) canal, which precedes valve formation. Here, we show that Npnt expression correlates with this process. Morpholino-mediated knockdown of Npnt prevents proper valve leaflet formation and trabeculation and results in greater than 85% lethality at 7 days post-fertilization. The earliest observed phenotype is an extended tube-like structure at the AV boundary. In addition, the expression of myocardial genes involved in cardiac valve formation (cspg2, fibulin 1, tbx2b, bmp4) is expanded and endocardial cells along the extended tube-like structure exhibit characteristics of AV cells (has2, notch1b and Alcam expression, cuboidal cell shape). Inhibition of has2 in npnt morphants rescues the endocardial, but not the myocardial, expansion. By contrast, reduction of BMP signaling in npnt morphants reduces the ectopic expression of myocardial and endocardial AV markers. Taken together, our results identify Npnt as a novel upstream regulator of Bmp4-Has2 signaling that plays a crucial role in AV canal differentiation.
Neue Perspektiven im Vormundschafts- und Pflegschaftsrecht : 9. Göttinger Workshop zum Familienrecht 2010
- Der vorliegende Band enthält die Referate des am 10. Dezember 2010 veranstalteten
9. Göttinger Workshops zum Familienrecht, der die aktuelle Novellierung des Vormundschaftsrechts
zum Gegenstand hatte.
Den Auftakt bildete die Darstellung des Reformbedarfs im Vormundschafts- und
Pflegschaftsrecht (Gisela Zenz), gefolgt von der Erläuterung des Gesetzentwurfs der
Bundesregierung (Thomas Meyer). Im Anschluss wurde der Frage nachgegangen,
ob und inwieweit das Betreuungsrecht als Vorbild für das neue Vormundschaftsrecht
herangezogen werden kann (Dieter Schwab). Einen Perspektivwechsel weg
vom Gesetzgeber und hin zum Mündel forderte der nachfolgende Beitrag, der die
Auswahl des passenden Vormunds für den individuellen Mündel thematisierte (Barbara
Seidenstücker). Abschließend wurden die strukturellen Probleme auf Seiten der
Jugendämter aufgezeigt (Hans-Werner Pütz) und das im Gesetzgebungsverfahren
vernachlässigte Problem beleuchtet, welche Konsequenzen sich aus dem Gesetzentwurf
für die Ergänzungspflegschaft ergeben (Thomas Meysen).
Reformbedarf im Recht der Vormundschaft/Pflegschaft
Functional genomic and advanced genetic studies reveal novel insights into the metabolism, regulation, and biology of Haloferax volcanii
- The genome sequence of Haloferax volcanii is available and several comparative genomic in silico studies were performed that yielded novel insight for example into protein export, RNA modifications, small non-coding RNAs, and ubiquitin-like Small Archaeal Modifier Proteins. The full range of functional genomic methods has been established and results from transcriptomic, proteomic and metabolomic studies are discussed. Notably, Hfx. volcanii is together with Halobacterium salinarum the only prokaryotic species for which a translatome analysis has been performed. The results revealed that the fraction of translationally-regulated genes in haloarchaea is as high as in eukaryotes. A highly efficient genetic system has been established that enables the application of libraries as well as the parallel generation of genomic deletion mutants. Facile mutant generation is complemented by the possibility to culture Hfx. volcanii in microtiter plates, allowing the phenotyping of mutant collections. Genetic approaches are currently used to study diverse biological questions–from replication to posttranslational modification—and selected results are discussed. Taken together, the wealth of functional genomic and genetic tools make Hfx. volcanii a bona fide archaeal model species, which has enabled the generation of important results in recent years and will most likely generate further breakthroughs in the future.
Academic faculty governance and recruitment decisions
- We analyze the implications of the governance structure in academic faculties for their recruitment decisions when competing for new researchers. The value to individual members through social interaction within the faculty depends on the average status of their fellow members. In recruitment decisions, incumbent members trade off the effect of entry on average faculty status against alternative uses of the recruitment budget if no entry takes place. We show that the best candidates join the best faculties but that they receive lower wages than some lesser ranking candidates. We also study the allocation of surplus created by the entry of a new faculty member and show that faculties with symmetric status distributions maximize their joint surplus under majority voting.
Influence of ground-state structure and Mg2+ binding on folding kinetics of the guanine-sensing riboswitch aptamer domain
- Riboswitch RNAs fold into complex tertiary structures upon binding to their cognate ligand. Ligand recognition is accomplished by key residues in the binding pocket. In addition, it often crucially depends on the stability of peripheral structural elements. The ligand-bound complex of the guanine-sensing riboswitch from Bacillus subtilis, for example, is stabilized by extensive interactions between apical loop regions of the aptamer domain. Previously, we have shown that destabilization of this tertiary loop–loop interaction abrogates ligand binding of the G37A/C61U-mutant aptamer domain (Gswloop) in the absence of Mg2+. However, if Mg2+ is available, ligand-binding capability is restored by a population shift of the ground-state RNA ensemble toward RNA conformations with pre-formed loop–loop interactions. Here, we characterize the striking influence of long-range tertiary structure on RNA folding kinetics and on ligand-bound complex structure, both by X-ray crystallography and time-resolved NMR. The X-ray structure of the ligand-bound complex reveals that the global architecture is almost identical to the wild-type aptamer domain. The population of ligand-binding competent conformations in the ground-state ensemble of Gswloop is tunable through variation of the Mg2+ concentration. We quantitatively describe the influence of distinct Mg2+ concentrations on ligand-induced folding trajectories both by equilibrium and time-resolved NMR spectroscopy at single-residue resolution.
Interaction of spin and vibrations in transport through single-molecule magnets
Maarten R. Wegewijs
- We study electron transport through a single-molecule magnet (SMM) and the interplay of its anisotropic spin with quantized vibrational distortions of the molecule. Based on numerical renormalization group calculations we show that, despite the longitudinal anisotropy barrier and small transverse anisotropy, vibrational fluctuations can induce quantum spin-tunneling (QST) and a QST-Kondo effect. The interplay of spin scattering, QST and molecular vibrations can strongly enhance the Kondo effect and induce an anomalous magnetic field dependence of vibrational Kondo side-bands.
(Acetonitrile-κN)chloridobis[2-(pyridin-2-yl)phenyl-κ2 C 1,N]iridium(III)
Jan W. Bats
- The IrIII atom of the title compound, [Ir(C11H8N)2Cl(CH3CN)], displays a distorted octahedral coordination. The pyridyl groups are in trans positions [N—Ir—N = 173.07 (10)°], while the phenyl groups are trans with respect to the acetonitrile and chloride groups [C—Ir—N = 178.13 (11) and C—Ir—Cl = 176.22 (9)°]. The pyridylphenyl groups only show a small deviation from planarity, with the dihedral angle between the planes of the two six-membered rings in each pyridylphenyl group being 5.6 (2) and 5.8 (1)°. The crystal packing shows intermolecular C—H[cdots, three dots, centered]Cl, C—H[cdots, three dots, centered]π(acetonitrile) and C—H[cdots, three dots, centered]π(pyridylphenyl) contacts.
Emergent inert adjoint scalar field in SU(2) Yang-Mills thermodynamics due to coarse-grained topological fluctuation
- We compute the phase and the modulus of an energy- and pressure-free, composite, adjoint, and
inert field φ in an SU(2) Yang-Mills theory at large temperatures. This field is physically relevant in describing part of the ground-state structure and the quasiparticle masses of excitations. The field φ possesses nontrivial S1-winding on the group manifold S3. Even at asymptotically high temperatures, where the theory reaches its Stefan-Boltzmann limit, the field φ, though strongly power suppressed, is conceptually relevant: its presence resolves the infrared problem of thermal perturbation theory.
Bedingungen und Auswirkungen regionaler Identität in Baden-Württemberg : "Schaffe, spare, Häusle bauen" versus "Über Baden lacht die Sonne, über Schwaben die ganze Welt"?