Attainment of sexuality inEnchytraeus fragmentosus Bell under laboratory conditions

Zusammenfassung Es wurde früher beschrieben, dassEnchytraeus fragmentosus Bell (Oligochaeta) keine Sexualorgane besitzt und sich nur durch Fragmentation fortpflanzt. Jetzt wurden männliche und weibliche Sexualorgane entdeckt, die sich wahrscheinlich als Folge veränderter Zuchtbedingungen entwickeln.

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This investigation was partially supported by the Department of Health, Education and Welfare, Public Health Service, No. AM 08632-04.     

Interferometric radar measurements of water level changes on the Amazon flood plain

Measurements of water levels in the main channels of rivers, upland tributaries and floodplain lakes are necessary for understanding flooding hazards, methane production, sediment transport and nutrient exchange. But most remote river basins have only a few gauging stations and these tend to be restricted to large river channels. Although radar remote sensing techniques using interferometric phase measurements have the potential to greatly improve spatial sampling, the phase is temporally incoherent over open water and has therefore not been used to determine water levels. Here we use interferometric synthetic aperture radar (SAR) data, acquired over the central Amazon by the Space Shuttle imaging radar mission, to measure subtle water level changes in an area of flooded vegetation on the Amazon flood plain. The technique makes use of the fact that flooded forests and floodplain lakes with emergent shrubs permit radar double-bounce returns from water and vegetation surfaces, thus allowing coherence to be maintained. Our interferometric phase observations show decreases in water levels of 7-11 cm per day for tributaries and lakes within approximately 20 km of a main channel and 2-5 cm per day at distances of approximately 80 km. Proximal floodplain observations are in close agreement with main-channel gauge records, indicating a rapid response of the flood plain to decreases in river stage. With additional data from future satellite missions, the technique described here should provide direct observations important for understanding flood dynamics and hydrologic exchange between rivers and flood plains.     

'Trapped rainbow' storage of light in metamaterials

Light usually propagates inside transparent materials in well known ways. However, recent research has examined the possibility of modifying the way the light travels by taking a normal transparent dielectric and inserting tiny metallic inclusions of various shapes and arrangements. As light passes through these structures, oscillating electric currents are set up that generate electromagnetic field moments; these can lead to dramatic effects on the light propagation, such as negative refraction. Possible applications include lenses that break traditional diffraction limits and 'invisibility cloaks' (refs 5, 6). Significantly less research has focused on the potential of such structures for slowing, trapping and releasing light signals. Here we demonstrate theoretically that an axially varying heterostructure with a metamaterial core of negative refractive index can be used to efficiently and coherently bring light to a complete standstill. In contrast to previous approaches for decelerating and storing light, the present scheme simultaneously allows for high in-coupling efficiencies and broadband, room-temperature operation. Surprisingly, our analysis reveals a critical point at which the effective thickness of the waveguide is reduced to zero, preventing the light wave from propagating further. At this point, the light ray is permanently trapped, its trajectory forming a double light-cone that we call an 'optical clepsydra'. Each frequency component of the wave packet is stopped at a different guide thickness, leading to the spatial separation of its spectrum and the formation of a 'trapped rainbow'. Our results bridge the gap between two important contemporary realms of science-metamaterials and slow light. Combined investigations may lead to applications in optical data processing and storage or the realization of quantum optical memories.     

Caveolin-1 interacts with the chaperone complex TCP-1 and modulates its protein folding activity

We report that caveolin-1, one of the major structural protein of caveolae, interacts with TCP-1, a hetero-oligomeric chaperone complex present in all eukaryotic cells that contributes mainly to the folding of actin and tubulin. The caveolin-TCP-1 interaction entails the first 32 amino acids of the N-terminal segment of caveolin. Our data show that caveolin-1 expression is needed for the induction of TCP-1 actin folding function in response to insulin stimulation. Caveolin-1 phosphorylation at tyrosine residue 14 induces the dissociation of caveolin-1 from TCP-1 and activates actin folding. We show that the mechanism by which caveolin-1 modulates TCP-1 activity is indirect and involves the cytoskeleton linker filamin. Filamin is known to bind caveolin-1 and to function as a negative regulator of insulin-mediated signaling. Our data support the notion that the caveolin-filamin interaction contributes to restore insulin-mediated phosphorylation of caveolin, thus allowing the release of active TCP-1. Received 17 November 2005; received after revision 1 December 2005; accepted 17 February 2006     

MYO5B mutations cause microvillus inclusion disease and disrupt epithelial cell polarity

Following homozygosity mapping in a single kindred, we identified nonsense and missense mutations in MYO5B, encoding type Vb myosin motor protein, in individuals with microvillus inclusion disease (MVID). MVID is characterized by lack of microvilli on the surface of enterocytes and occurrence of intracellular vacuolar structures containing microvilli. In addition, mislocalization of transferrin receptor in MVID enterocytes suggests that MYO5B deficiency causes defective trafficking of apical and basolateral proteins in MVID.     

Mast cells in the skin of normal,hairless and athymic mice

Summary The skin of congenitally athymicnu/nu mice is rich in mast cells which stain metachromatically, contain histamine and 5-hydroxytryptamine, and participate in the PCA reaction. Mast cells of athymic mice have thus the attributes of normal mast cells.This work was supported by grants from the Swiss National Science Foundation (No. 3.516.71 and 3.234.74) and the Fritz Hoffmann-La-Roche-Stiftung.The skilful technical assistance of MissR. Keist is gratefully acknowledged.     

Changes in cellular noradrenaline fluorescence in the denervated rat superior cerical ganglion

Summary The microfluorimetrical investigation showed that in the principal perikarya of the rat superior cervical ganglion, after inhibition of noradrenaline-synthesis and unilateral preganglionic axotomy, the fluorescence of newly synthesized noradrenaline was most intense at the periphery of the perikarya of the intact side.The authors are deeply indebted to Mr H. Petermann, and to Mr B. Rombach, Ciba-Geigy Ltd. for their mathematical support.     

Direct measurement of proton transfer rates to a group controlling the dihydropyridine-sensitive Ca2+ channel

Protons participate in most biologically important reactions, as substrates, products, cofactors and modulators, and proton transport is an essential step in energy transduction. The dynamics of protonation reactions have been studied extensively in solution and in model systems involving lipid-water interfaces, but have never been resolved at the timescale of the elementary molecular event. Here we show that, under appropriate conditions, binding and unbinding reactions of single protons and deuterium ions to a single site on the L-type calcium channel can be resolved and the protonation and deprotonation rates quantified. The protonation rate constant considerably exceeds previous estimates obtained in simpler systems. The functional consequences of channel protonation is a threefold reduction of the channel conductance, independent of the applied voltage. The data are consistent with the presence of a single protonatable group with pK in the physiological pH range, close to the external mouth of the channel. The two conductance levels of the open channel might be explained by greatly differing local potentials associated with the protonated and deprotonated state of the group.