Search

Hypothalamic tanycytes are glial-like glucosensitive cells that contact the cerebrospinal fluid of the third ventricle, and send processes into the hypothalamic nuclei that control food intake and body weight. The mechanism of tanycyte glucosensing remains undetermined. While tanycytes express the components associated with the glucosensing of the pancreatic β cell, they respond to nonmetabolisable glucose analogues via an ATP receptor-dependent mechanism. Here, we show that tanycytes in rodents respond to non-nutritive sweeteners known to be ligands of the sweet taste (Tas1r2/Tas1r3) receptor. The initial sweet tastant-evoked response, which requires the presence of extracellular Ca2+, leads to release of ATP and a larger propagating Ca2+ response mediated by P2Y1 receptors. In Tas1r2 null mice the proportion of glucose nonresponsive tanycytes was greatly increased in these mice, but a subset of tanycytes retained an undiminished sensitivity to glucose. Our data demonstrate that the sweet taste receptor mediates glucosensing in about 60% of glucosensitive tanycytes while the remaining 40% of glucosensitive tanycytes use some other, as yet unknown mechanism.

Der Ausbau der Wassernutzung am Kongo könnte der Region einen Entwicklungsschub verschaffen, droht aber mit der Begünstigung partikulärer Nutzungsinteressen einherzugehen. In seinem weitläufigen Einzugsgebiet ist der Fluss das wichtigste Verkehrsnetz und die Lebensader des afrikanischen Regenwalds, der wiederum die Existenzgrundlage von Millionen Menschen sichert. Die Wasser- und Nahrungsmittelversorgung der Region ließe sich mit seinen Ressourcen deutlich verbessern, die Hydroenergiepotentiale könnten den Strombedarf des gesamten Kontinents decken. Der geplante Bau weiterer Großdämme an den Inga-Fällen zeigt, dass die zehn Anrainerstaaten gemeinsame Ziele verfolgen, aber auch, dass sich Konflikte zwischen einzelnen Sektoren verschärfen. Die inkonsistente Haltung Deutschlands in heiklen Grundsatzfragen der Entwicklungszusammenarbeit und Wasseraußenpolitik erschwert es, diese Prozesse konstruktiv zu begleiten. (Autorenreferat)

Der Ausbau der Wassernutzung am Kongo könnte der Region einen Entwicklungsschub verschaffen, droht aber mit der Begünstigung partikulärer Nutzungsinteressen einherzugehen. In seinem weitläufigen Einzugsgebiet ist der Fluss das wichtigste Verkehrsnetz und die Lebensader des afrikanischen Regenwalds, der wiederum die Existenzgrundlage von Millionen Menschen sichert. Die Wasser- und Nahrungsmittelversorgung der Region ließe sich mit seinen Ressourcen deutlich verbessern, die Hydroenergiepotentiale könnten den Strombedarf des gesamten Kontinents decken. Der geplante Bau weiterer Großdämme an den Inga-Fällen zeigt, dass die zehn Anrainerstaaten gemeinsame Ziele verfolgen, aber auch, dass sich Konflikte zwischen einzelnen Sektoren verschärfen. Die inkonsistente Haltung Deutschlands in heiklen Grundsatzfragen der Entwicklungszusammenarbeit und Wasseraußenpolitik erschwert es, diese Prozesse konstruktiv zu begleiten.

Making greater of use of the waters of the Congo could boost development across - and beyond - the region, but threatens to favour particular users' interests at the expense of others. Within its enormous catchment area, the Congo is the dominant transport network and the lifeblood of the African rain forest, upon which millions depend for their livelihoods. Tapping the river's resources could significantly improve the region's water and food supplies, while its hydro-energy potential could theoretically satisfy the electricity needs of the entire continent. Plans to construct more major dams at the Inga Falls demonstrate that the ten Congo Basin states are pursuing common goals - but also having to deal with sharpening intersectoral conflicts. An inconsistent line on dam-building makes it harder for Germany to play a constructive role in these development processes.

The space shuttle main engine plume deposited between 100 and 115 km altitude is a valuable tracer for global-scale dynamical processes. Several studies have shown that this plume can reach the Arctic or Antarctic to form bursts of polar mesospheric clouds (PMCs) within a few days. The rapid transport of the shuttle plume is currently not reproduced by general circulation models and is not well understood. To help delineate the issues, we present the complete satellite datasets of shuttle plume observations by the Sounding of the Atmosphere using Broadband Emission Radiometry instrument and the Sub-Millimeter Radiometer instrument. From 2002 to 2011 these two instruments observed 27 shuttle plumes in over 600 limb scans of water vapor emission, from which we derive both advective meridional transport and diffusive spreading. Each plume is deposited at virtually the same place off the United States east coast so our results are relevant to northern mid-latitudes. We find that the advective transport for the first 6-18 h following deposition depends on the local time (LT) of launch: shuttle plumes deposited later in the day (similar to 13-22 LT) typically move south whereas they otherwise typically move north. For these younger plumes rapid transport is most favorable for launches at 6 and 18 LT, when the displacement is 100 in latitude corresponding to an average wind speed of 30 m/s. For plumes between 18 and 30 h old some show average sustained meridional speeds of 30 m/s. For plumes between 30 and 54 h old the observations suggest a seasonal dependence to the meridional transport, peaking near the beginning of year at 24 m/s. The diffusive spreading of the plume superimposed on the transport is on average 23 m/s in 24 h. The plume observations show large variations in both meridional transport and diffusive spreading so that accurate modeling requires knowledge of the winds specific to each case. The combination of transport and spreading from the STS-118 plume in August 2007 formed bright PMCs between 75 and 85 degrees N a day after launch. These are the highest latitude Arctic PMCs formed by shuttle exhaust reported to date.

Hypothalamic tanycytes are glial‐like glucosensitive cells that contact the cerebrospinal fluid of the third ventricle, and send processes into the hypothalamic nuclei that control food intake and body weight. The mechanism of tanycyte glucosensing remains undetermined. While tanycytes express the components associated with the glucosensing of the pancreatic β cell, they respond to nonmetabolisable glucose analogues via an ATP receptor‐dependent mechanism. Here, we show that tanycytes in rodents respond to non‐nutritive sweeteners known to be ligands of the sweet taste (Tas1r2/Tas1r3) receptor. The initial sweet tastant‐evoked response, which requires the presence of extracellular Ca2+, leads to release of ATP and a larger propagating Ca2+ response mediated by P2Y1 receptors. In Tas1r2 null mice the proportion of glucose nonresponsive tanycytes was greatly increased in these mice, but a subset of tanycytes retained an undiminished sensitivity to glucose. Our data demonstrate that the sweet taste receptor mediates glucosensing in about 60% of glucosensitive tanycytes while the remaining 40% of glucosensitive tanycytes use some other, as yet unknown mechanism.

In this paper, we present a HARMonized dataset of OZone profiles (HARMOZ) based on limb and occultation measurements from Envisat (GOMOS, MIPAS and SCIAMACHY), Odin (OSIRIS, SMR) and SCISAT (ACE-FTS) satellite instruments. These measurements provide high-vertical-resolution ozone profiles covering the altitude range from the upper troposphere up to the mesosphere in years 2001–2012. HARMOZ has been created in the framework of the European Space Agency Climate Change Initiative project. The harmonized dataset consists of original retrieved ozone profiles from each instrument, which are screened for invalid data by the instrument teams. While the original ozone profiles are presented in different units and on different vertical grids, the harmonized dataset is given on a common pressure grid in netCDF (network common data form)-4 format. The pressure grid corresponds to vertical sampling of ~ 1 km below 20 km and 2–3 km above 20 km. The vertical range of the ozone profiles is specific for each instrument, thus all information contained in the original data is preserved. Provided altitude and temperature profiles allow the representation of ozone profiles in number density or mixing ratio on a pressure or altitude vertical grid. Geolocation, uncertainty estimates and vertical resolution are provided for each profile. For each instrument, optional parameters, which are related to the data quality, are also included. For convenience of users, tables of biases between each pair of instruments for each month, as well as bias uncertainties, are provided. These tables characterize the data consistency and can be used in various bias and drift analyses, which are needed, for instance, for combining several datasets to obtain a long-term climate dataset. This user-friendly dataset can be interesting and useful for various analyses and applications, such as data merging, data validation, assimilation and scientific research. The dataset is available at http://www.esa-ozone-cci.org/?q=node/161 or at doi:10.5270/esa-ozone_cci-limb_occultation_profiles-2001_2012-v_1-201308.

Stratospheric water vapour (SWV) is an important component of the Earth's atmosphere as it affects both radiative balance and the chemistry of the atmosphere. Key processes driving changes in SWV through the 21st century include dehydration of air masses transiting the cold-point tropopause (CPT) and methane oxidation. Increasing surface temperatures may strengthen the Brewer-Dobson circulation, such that more methane is transported into the stratosphere where it can be oxidised to SWV. We use a chemistry-climate model to simulate changes in SWV through the 21st century following the four canonical Representative Concentration Pathways (RCPs). Furthermore, we quantify the contribution that methane oxidation makes to SWV following each of the RCPs. The methane contribution to SWV maximises in the upper stratosphere, however modelled SWV trends are found to be driven predominantly by warming of the CPT and strengthening of the Brewer-Dobson circulation rather than by increasing methane oxidation. SWV changes by −5 % to 60 % (depending on the location in the atmosphere and emissions scenario) and increases in the lower stratosphere in all RCPs through the 21st century. Because the lower stratosphere is where water vapour radiative forcing maximises, SWV's influence on surface climate is also expected to increase through the 21st century.

In this paper, a flow-level traffic model for evaluating Long Term Evolution Advanced networks is presented. The model includes the characteristics of the Transmission Control Protocol version Cubic. Live network measurements of flow and user data volumes in the busy hour were used to parameterize the presented statistical model. Furthermore, an approach for combining LTE-Advanced system-level simulation with detailed data traffic modeling is presented. The model is exemplary used to show the impact of the system load and file size on the estimated user throughput. Further, TCP user throughput gains of 4×2 and 4×4 SU-MIMO compared to 2×2 SU-MIMO are shown.

The stratospheric response to anthropogenic changes and ist feedback on tropospheric climate and weather are of growing interest in climate research and numerical weather prediction. The SHARP-2016 workshop discussed recent progress and future directions in the research on stratospheric change and its implications for climate and weather with focus on Brewer-Dobson circulation, Stratospheric ozone, Stratosphere-troposphere coupling, Stratospheric water vapour.

One key to animal survival is the detection and avoidance of potentially harmful compounds by their bitter taste. Variable numbers of taste 2 receptor genes expressed in the gustatory end organs enable bony vertebrates (Euteleostomi) to recognize numerous bitter chemicals. It is believed that the receptive ranges of bitter taste receptor repertoires match the profiles of bitter chemicals that the species encounter in their diets. Human and mouse genomes contain pairs of orthologous bitter receptor genes that have been conserved throughout evolution. Moreover, expansions in both lineages generated species-specific sets of bitter taste receptor genes. It is assumed that the orthologous bitter taste receptor genes mediate the recognition of bitter toxins relevant for both species, whereas the lineage-specific receptors enable the detection of substances differently encountered by mice and humans. By challenging 34 mouse bitter taste receptors with 128 prototypical bitter substances in a heterologous expression system, we identified cognate compounds for 21 receptors, 19 of which were previously orphan receptors. We have demonstrated that mouse taste 2 receptors, like their human counterparts, vary greatly in their breadth of tuning, ranging from very broadly to extremely narrowly tuned receptors. However, when compared with humans, mice possess fewer broadly tuned receptors and an elevated number of narrowly tuned receptors, supporting the idea that a large receptor repertoire is the basis for the evolution of specialized receptors. Moreover, we have demonstrated that sequence-orthologous bitter taste receptors have distinct agonist profiles. Species-specific gene expansions have enabled further diversification of bitter substance recognition spectra.

In the course of its territorial expansion, Islamic State (IS, ISIL or ISIS) has brought under its control strategically significant water resources and large parts of the water infrastructure in Syria and Iraq. It has seized several important dams on the Euphrates and Tigris as part of its expansion strategy and, particularly since 2014, has used water as a weapon in a number of ways. This practice has disastrous consequences, and it is virtually impossible for external actors to prevent it. And yet, even IS’s room for manoeuvre is limited since a functioning water and electricity supply in the areas that it has captured is of existential importance for the militia. However, the anti-IS coalition’s intensified military interventions since the Paris attacks put the militia under severe pressure. Should IS be forced into extensive withdrawals, then whole regions will be at risk of dramatic and wide-spread flooding. (author's abstract)

In the course of its territorial expansion, Islamic State (IS, ISIL or ISIS) has brought under its control strategically significant water resources and large parts of the water infrastructure in Syria and Iraq. It has seized several important dams on the Euphrates and Tigris as part of its expansion strategy and, particularly since 2014, has used water as a weapon in a number of ways. This practice has disastrous consequences, and it is virtually impossible for external actors to prevent it. And yet, even IS's room for manoeuvre is limited since a functioning water and electricity supply in the areas that it has captured is of existential importance for the militia. However, the anti-IS coalition's intensified military interventions since the Paris attacks put the militia under severe pressure. Should IS be forced into extensive withdrawals, then whole regions will be at risk of dramatic and wide-spread flooding. (SWP Comments)

In the framework of the second SPARC (Stratosphere-troposphere Processes And their Role in Climate) water assessment (WAVAS-II), the amplitudes and phases of the annual, semi-annual and quasi-biennial variation in stratospheric and lower mesospheric water were compared considering 32 data sets from 13 different satellite instruments. These comparisons aimed to provide a comprehensive overview of the typical uncertainties in the observational database which can be considered in subsequent observational and modelling studies. For the amplitudes, a good agreement of their latitude and altitude distribution was found. Quantitatively there were differences in particular at high latitudes, close to the tropopause and in the lower mesosphere. Here the standard deviation over all data sets typically exceeded 0.2 ppmv for the annual variation and 0.1 ppmv for the semi-annual and quasi-biennial variation. For the phase, larger differences between the data sets were found in the lower mesosphere. Generally the smallest phase uncertainties can be observed in regions where the amplitude of the variability is large. The standard deviations over all data sets were typically smaller than a month for the annual and semi-annual variation and smaller than 5 months for the quasi-biennial variation. The amplitude and phase differences among the data sets could be explained by a combination of reasons. An important role play temporal variations of systematic errors and differences in the temporal and spatial sampling. In addition, differences in the considered time periods, the vertical resolution of the data, influences of clouds, aerosols as well as non local thermodynamic equilibrium (NLTE) effects cause differences between the individual data sets.

Characterization of the peripheral taste system relies on the identification and visualization of the different taste bud cell types. So far, genetic strategies to label taste receptor cells are limited to sweet, sour, and salty detecting cells. To visualize Tas1r1 umami and Tas2r131 bitter sensing cells, we generated animals in which the Tas1r1 and Tas2r131 open reading frames are replaced by expression cassettes containing the fluorescent proteins mCherry or hrGFP, respectively. These animals enabled us to visualize and quantify the entire oral Tas1r1 and Tas2r131 cell populations. Tas1r1-mCherry cells were predominantly detected in fungiform papillae, whereas Tas2r131-hrGFP cells, which are ~4-fold more abundant, were mainly present in foliate and vallate papillae. In the palate, both cell types were similarly distributed. Mice carrying both recombinant alleles demonstrated completely segregated Tas1r1 and Tas2r131 cell populations. Only ~50% of the entire bitter cell population expressed hrGFP, indicating that bitter taste receptor cells express a subset of the bitter receptor repertoire. In extragustatory tissues, mCherry fluorescence was observed in testis and hrGFP fluorescence in testis, thymus, vomeronasal organ, and respiratory epithelium, suggesting that only few extraoral sites express Tas2r131 and Tas1r1 receptors at levels comparable to taste tissue.

It is well established that variations in polar stratospheric winds can affect mesospheric temperatures through changes in the filtering of gravity wave fluxes, which drive a residual circulation in the mesosphere. The Canadian Middle Atmosphere Model (CMAM) is used to examine this vertical coupling mechanism in the context of the mesospheric response to the Antarctic ozone hole. It is found that the response differs significantly between late spring and early summer, because of a changing balance between the competing effects of parametrised gravity wave drag (GWD) and changes in resolved wave drag local to the mesosphere. In late spring, the strengthened stratospheric westerlies arising from the ozone hole lead to reduced eastward GWD in the mesosphere and a warming of the polar mesosphere, just as in the well known mesospheric response to sudden stratospheric warmings, but with an opposite sign. In early summer, with easterly flow prevailing over most of the polar stratosphere, the strengthened easterly wind shear within the mesosphere arising from the westward GWD anomaly induces a positive resolved wave drag anomaly through baroclinic instability. The polar cooling induced by this process completely dominates the upper mesospheric response to the ozone hole in early summer. Consequences for the past and future evolution of noctilucent clouds are discussed.

Cholesterol of glial origin promotes synaptogenesis (Mauch et al., (2001) Science 294:1354–1357). Because in the hippocampus local estradiol synthesis is essential for synaptogenesis, we addressed the question of whether cholesterol-promoted synapse formation results from the function of cholesterol as a precursor of estradiol synthesis in this brain area. To this end, we treated hippocampal cultures with cholesterol, estradiol, or with letrozole, a potent aromatase inhibitor. Cholesterol increased neuronal estradiol release into the medium, the number of spine synapses in hippocampal slice cultures, and immunoreactivity of synaptic proteins in dispersed cultures. Simultaneous application of cholesterol and letrozole or blockade of estrogen receptors by ICI 182 780 abolished cholesterol-induced synapse formation. As a further approach, we inhibited the access of cholesterol to the first enzyme of steroidogenesis by knock-down of steroidogenic acute regulatory protein, the rate-limiting step in steroidogenesis. A rescue of reduced synaptic protein expression in transfected cells was achieved by estradiol but not by cholesterol. Our data indicate that in the hippocampus cholesterol-promoted synapse formation requires the conversion of cholesterol to estradiol. © 2009 Wiley-Liss, Inc.

The Hygrosonde-2 campaign took place on 16 December 2001 at Esrange/Sweden (68° N, 21° E) with the aim to investigate the small scale distribution of water vapour in the middle atmosphere in the vicinity of the Arctic polar vortex. In situ balloon and rocket-borne measurements of water vapour were performed by means of OH fluorescence hygrometry. The combined measurements yielded a high resolution water vapour profile up to an altitude of 75 km. Using the characteristic of water vapour being a dynamical tracer it was possible to directly relate the water vapour data to the location of the polar vortex edge, which separates air masses of different character inside and outside the polar vortex. The measurements probed extra-vortex air in the altitude range between 45 km and 60 km and vortex air elsewhere. Transitions between vortex and extra-vortex usually coincided with wind shears caused by gravity waves which advect air masses with different water vapour volume mixing ratios. From the combination of the results from the Hygrosonde-2 campaign and the first flight of the optical hygrometer in 1994 (Hygrosonde-1) a clear picture of the characteristic water vapour distribution inside and outside the polar vortex can be drawn. Systematic differences in the water vapour concentration between the inside and outside of the polar vortex can be observed all the way up into the mesosphere. It is also evident that in situ measurements with high spatial resolution are needed to fully account for the small-scale exchange processes in the polar winter middle atmosphere.

The air induced broadening coefficients of the pure rotational transitions of H 2 O at 556.936 GHz ( 1 10 ← 1 01 ) , and 752.033 GHz ( 2 11 ← 2 02 ) were measured by terahertz time-domain spectroscopy. The air broadening coefficient was determined to be 4.012 ( 30 ) MHz Torr - 1 for the 556.936 GHz line and 3.964 ( 40 ) MHz Torr - 1 for the 752.033 GHz line, respectively. The present broadening coefficients for the 556.936 GHz water line are significantly smaller than those of Markov and Krupnov [Measurements of the pressure shift of the 1(10)–1(01) water line at 556.936 GHz produced by mixtures of gases. J Mol Spect 1995:172;211–4] but relatively close to the values of the HITRAN database. The measured data may improve the accuracy of the abundance of water vapor retrieved from spectra obtained by the Odin/SMR satellite instrument. The effect on the satellite retrieval processing is discussed.

The NCAs of the following five amino acids were polymerized in bulk at 120 °C without addition of a catalyst or initiator: sarcosine (Sar), L-alanine (L-Ala), D,L-phenylalanine (D,L-Phe), D,L-leucine (D,L-Leu) and D,L-valine (D,L-Val). The virgin reaction products were characterized by viscosity measurements 13C NMR spectroscopy and MALDI-TOF mass spectrometry. In addition to numerous low molar mass byproducts cyclic polypeptides were formed as the main reaction products in the mass range above 800 Da. Two types of cyclic oligo- and polypeptides were detected in all cases with exception of sarcosine NCA, which only yielded one class of cyclic polypeptides. The efficient formation of cyclic oligo- and polypeptides explains why high molar mass polymers cannot be obtained by thermal polymerizations of α-amino acid NCAs. Various polymerization mechanisms were discussed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4012–4020, 2008