Drosophila Stardust is a partner of Crumbs in the control of epithelial cell polarity.

The polarized architecture of epithelial cells depends on the highly stereotypic distribution of cellular junctions and other membrane-associated protein complexes. In epithelial cells of the Drosophila embryo, three distinct domains subdivide the lateral plasma membrane. The most apical one comprises the subapical complex (SAC). It is followed by the zonula adherens (ZA) and, further basally, by the septate junction. A core component of the SAC is the transmembrane protein Crumbs, the cytoplasmic domain of which recruits the PDZ-protein Discs Lost into the complex. Cells lacking crumbs or the functionally related gene stardust fail to organize a continuous ZA and to maintain cell polarity. Here we show that stardust provides an essential component of the SAC. Stardust proteins colocalize with Crumbs and bind to the carboxy-terminal amino acids of its cytoplasmic tail. We introduce two different Stardust proteins here: one MAGUK protein, characterized by a PDZ domain, an SH3 domain and a guanylate kinase domain; and a second isoform comprising only the guanylate kinase domain. The Stardust proteins represent versatile candidates as structural and possibly regulatory constituents of the SAC, a crucial element in the control of epithelial cell polarity.     

Finite lifetime of turbulence in shear flows

Generally, the motion of fluids is smooth and laminar at low speeds but becomes highly disordered and turbulent as the velocity increases. The transition from laminar to turbulent flow can involve a sequence of instabilities in which the system realizes progressively more complicated states, or it can occur suddenly. Once the transition has taken place, it is generally assumed that, under steady conditions, the turbulent state will persist indefinitely. The flow of a fluid down a straight pipe provides a ubiquitous example of a shear flow undergoing a sudden transition from laminar to turbulent motion. Extensive calculations and experimental studies have shown that, at relatively low flow rates, turbulence in pipes is transient, and is characterized by an exponential distribution of lifetimes. They also suggest that for Reynolds numbers exceeding a critical value the lifetime diverges (that is, becomes infinitely large), marking a change from transient to persistent turbulence. Here we present experimental data and numerical calculations covering more than two decades of lifetimes, showing that the lifetime does not in fact diverge but rather increases exponentially with the Reynolds number. This implies that turbulence in pipes is only a transient event (contrary to the commonly accepted view), and that the turbulent and laminar states remain dynamically connected, suggesting avenues for turbulence control.     

Neocortical excitation/inhibition balance in information processing and social dysfunction

Severe behavioural deficits in psychiatric diseases such as autism and schizophrenia have been hypothesized to arise from elevations in the cellular balance of excitation and inhibition (E/I balance) within neural microcircuitry. This hypothesis could unify diverse streams of pathophysiological and genetic evidence, but has not been susceptible to direct testing. Here we design and use several novel optogenetic tools to causally investigate the cellular E/I balance hypothesis in freely moving mammals, and explore the associated circuit physiology. Elevation, but not reduction, of cellular E/I balance within the mouse medial prefrontal cortex was found to elicit a profound impairment in cellular information processing, associated with specific behavioural impairments and increased high-frequency power in the 30-80?Hz range, which have both been observed in clinical conditions in humans. Consistent with the E/I balance hypothesis, compensatory elevation of inhibitory cell excitability partially rescued social deficits caused by E/I balance elevation. These results provide support for the elevated cellular E/I balance hypothesis of severe neuropsychiatric disease-related symptoms.     

Carboxymethyl cellulose additives in penicillins and the elicitation of anaphylactic reactions

Zusammenfassung Penicilloylierte Carboxymethylzellulose bildet sich schon in der Kälte beim Stehen von Penicillinlösungen mit Carboxymethylzellulose. Die entstehenden Konjugate sind befähigt, penicilloylspezifische, kutane anaphylaktische Reaktionen auszulösen.     

Über ein gebundenes Gibberellin ausPhaseolus coccineus L.

Summary In addition to gibberellins A₁, A₅, A₆ and A₈ previously isolated fromPhaseolus coccineus L., the occurrence of gibberellin A₃ and of 5 new gibberellin-like substances «Phaseolus -» was demonstrated. «Phaseolus» was proved to be a gibberellin bound to carbohydrates and ninhydrin-positive compounds.

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Gibberelline, II. Mitteilung. — I. Mitt. sieheG. Sembdner, R. Gross undK. Schreiber, Exper.18, 584 (1962).