24 research outputs found
Anisotropy of Electrical Transport and Superconductivity in Metal Chains of Nb2Se3
In this work we have shown bulk superconductivity and studied the anisotropy
in both the normal and superconducting states in quasi-1D conductor Nb2Se3.
Electron - electron Umklapp scattering dominates electronic transport along the
direction of Nb metal chains as well as perpendicular to it. The
superconducting state is rather anisotropic with possible multi - band
features.Comment: 5 pages, 5 figure
The small GTPase Rab29 is a common regulator of immune synapse assembly and ciliogenesis
Acknowledgements We wish to thank Jorge GalĂĄn, Gregory Pazour, Derek Toomre, Giuliano Callaini, Joel Rosenbaum, Alessandra Boletta and Francesco Blasi for generously providing reagents and for productive discussions, and Sonia Grassini for technical assistance. The work was carried out with the financial support of Telethon (GGP11021) and AIRC.Peer reviewedPostprin
Recommended from our members
From insect to man: Photorhabdus sheds light on the emergence of human pathogenicity
Photorhabdus are highly effective insect pathogenic bacteria that exist in a mutualistic relationship with Heterorhabditid nematodes. Unlike other members of the genus, Photorhabdus asymbiotica can also infect humans. Most Photorhabdus cannot replicate above 34°C, limiting their host-range to poikilothermic invertebrates. In contrast, P. asymbiotica must necessarily be able to replicate at 37°C or above. Many well-studied mammalian pathogens use the elevated temperature of their host as a signal to regulate the necessary changes in gene expression required for infection. Here we use RNA-seq, proteomics and phenotype microarrays to examine temperature dependent differences in transcription, translation and phenotype of P. asymbiotica at 28°C versus 37°C, relevant to the insect or human hosts respectively. Our findings reveal relatively few temperature dependant differences in gene expression. There is however a striking difference in metabolism at 37°C, with a significant reduction in the range of carbon and nitrogen sources that otherwise support respiration at 28°C. We propose that the key adaptation that enables P. asymbiotica to infect humans is to aggressively acquire amino acids, peptides and other nutrients from the human host, employing a so called ânutritional virulenceâ strategy. This would simultaneously cripple the host immune response while providing nutrients sufficient for reproduction. This might explain the severity of ulcerated lesions observed in clinical cases of Photorhabdosis. Furthermore, while P. asymbiotica can invade mammalian cells they must also resist immediate killing by humoral immunity components in serum. We observed an increase in the production of the insect Phenol-oxidase inhibitor Rhabduscin normally deployed to inhibit the melanisation immune cascade. Crucially we demonstrated this molecule also facilitates protection against killing by the alternative human complement pathway
Leishmania infantum Asparagine Synthetase A Is Dispensable for Parasites Survival and Infectivity
A growing interest in asparagine (Asn) metabolism has currently been observed in cancer and infection fields. Asparagine synthetase (AS) is responsible for the conversion of aspartate into Asn in an ATP-dependent manner, using ammonia or glutamine as a nitrogen source. There are two structurally distinct AS: the strictly ammonia dependent, type A, and the type B, which preferably uses glutamine. Absent in humans and present in trypanosomatids, AS-A was worthy of exploring as a potential drug target candidate. Appealingly, it was reported that AS-A was essential in Leishmania donovani, making it a promising drug target. In the work herein we demonstrate that Leishmania infantum AS-A, similarly to Trypanosoma spp. and L. donovani, is able to use both ammonia and glutamine as nitrogen donors. Moreover, we have successfully generated LiASA null mutants by targeted gene replacement in L. infantum, and these parasites do not display any significant growth or infectivity defect. Indeed, a severe impairment of in vitro growth was only observed when null mutants were cultured in asparagine limiting conditions. Altogether our results demonstrate that despite being important under asparagine limitation, LiAS-A is not essential for parasite survival, growth or infectivity in normal in vitro and in vivo conditions. Therefore we exclude AS-A as a suitable drug target against L. infantum parasites
Decadal variations in wave heights off Cape Kelba, Saaremaa Island, and their relationships with changes in wind climate
Based on wind data from the Vilsandi meteorological station and a 5-month
calibration measurement with a bottom-mounted Recording Doppler Current
Profiler (RDCP), a semi-empirical hindcast of wave parameters near the quickly
developing accumulative Kelba Spit is presented for the period 1966â2006. The
significant wave heights with a gross mean value of 0.56 m exhibited some
quasiperiodic cycles, with the last high stage in 1980â95 and a decreasing overall
trend of â0.001 m per year. At the same time, both the frequency and intensity of
high wave events showed rising trends, and the mean wave heights during winter
(December to February) increased as well. As the study area has the longest fetches
in westerly directions, the discussed tendencies in wave conditions are sensitive to
regional changes in the wind climate and can be related to a decrease in the local
average wind speed on the one hand, but an intensification of westerly winds,
storm events and the wintertime NAO index on the other. The roughest wave storms on record were associated with prominent W-storms on 2 November 1969
and 9 January 2005; a few other extreme wind events (e.g. in 1967, 1999, 2001),
however, did not yield equally prominent waves
Currents and waves in the Northern Gulf of Riga: measurement and long-term hindcast
Based on measurements of waves and currents obtained for a period of 302 days with
a bottom-mounted RDCP (Recording Doppler Current Profiler) at two differently
exposed locations, a model for significant wave height was calibrated separately for
those locations; in addition, the Gulf of Riga-Vainameri 2D model was validated,
and the hydrodynamic conditions were studied. Using wind forcing data from the
Kihnu meteorological station, a set of current, water exchange and wave hindcasts
were obtained for the period 1966â2011. Current patterns in the Gulf and in the
straits were wind-dependent with characteristic wind switch directions. The Matsi
coast was prone to upwelling in persistent northerly wind conditions. During the hindcast period, currents increased along the Koiguste coast and in the Suur Strait,
waves decreased noticeably off Koiguste but fluctuated without a clear linear trend
near Matsi. The spatially contrasting results for differently exposed coasts were
related to the corresponding variations in local wind conditions and to changes in
atmospheric circulation patterns over northern Europe
Estimation of sea level rise and storm surge risks along the coast of Estonia, Baltic Sea â a tool for coastal management
The aim of the paper is to present statistical analysis of the sea level data obtained from the Estonian coastal tide gauges over the period 1842â2009, to assess storm surge risks and to discuss climate change related mitigation and management issues in the coastal zone of Estonia. Long-term variations of both mean and extreme sea level values were studied in the Eastern section of the nearly tideless Baltic Sea. Influenced by postglacial land uplift, the series of relative sea level displayed slightly varying trends. The remarkably steep rise in annual maximum sea levels (2â12 mm/yr) could be explained by the local response to the changing regional wind climate. Due to its windward location, the sea level variations in the semi-enclosed study area are sensitive to the changes in cyclonic activity. Maximum value analysis revealed that in case of the south-westerly exposed PĂ€rnu Bay, two storm surge events (253 in 1967 and 275 cm in 2005) were inconsistent with the theoretical distributions, which indicate that, in some locations, the most extreme sea level events are hardly predictable by means of return statistics. The parameters of maximum expected storm surges were estimated on the basis of hydrodynamic modelling
Cyclone Gudrun in January 2005 and modelling its hydrodynamic consequences in the Estonian coastal waters
Meteorological parameters of windstorm Gudrun on 8â9 January 2005 and its hydrodynamic and environmental consequences are analysed on the basis of observational data and hydrodynamic modelling. The study focuses mainly on describing events and reception in Estonia. We estimate that in meteorological terms, the cyclone was among the five most powerful ones in recorded history. Considering also the new highest storm surge record (275 cm in PĂ€rnu), extensive property damage and massive media coverage, it became the most influential natural disaster in Estonia. Using a shallow sea 2D hydrodynamic model with a 1-km grid step, a hindcast modelling study of the sea level was carried out. Hydrodynamic simulations suggest that an inflow of 24 km3 (5.4% of the Gulf's average volume) occurred in the Gulf of Riga. The sub-basin of the VĂ€inameri was nearly entirely flushed through by more saline and nutrient-poorer water from the Baltic Proper. The simulated current velocities, sea levels and wave parameters indicate that prominent coastline changes and replacement of sediments could have occurred within a single day