Folding-competent and folding-defective forms of Ricin A chain have different fates following retrotranslocation from the endoplasmic reticulum

We report that a toxic polypeptide retaining the potential to refold upon dislocation from the endoplasmic reticulum (ER) to the cytosol (ricin A chain; RTA) and a misfolded version that cannot (termed RTAΔ), follow ER-associated degradation (ERAD) pathways in Saccharomyces cerevisiae that substantially diverge in the cytosol. Both polypeptides are dislocated in a step mediated by the transmembrane Hrd1p ubiquitin ligase complex and subsequently degraded. Canonical polyubiquitylation is not a prerequisite for this interaction because a catalytically inactive Hrd1p E3 ubiquitin ligase retains the ability to retrotranslocate RTA, and variants lacking one or both endogenous lysyl residues also require the Hrd1p complex. In the case of native RTA, we established that dislocation also depends on other components of the classical ERAD-L pathway as well as an ongoing ER–Golgi transport. However, the dislocation pathways deviate strikingly upon entry into the cytosol. Here, the CDC48 complex is required only for RTAΔ, although the involvement of individual ATPases (Rpt proteins) in the 19S regulatory particle (RP) of the proteasome, and the 20S catalytic chamber itself, is very different for the two RTA variants. We conclude that cytosolic ERAD components, particularly the proteasome RP, can discriminate between structural features of the same substrate

Damping device for a stationary labyrinth seal

A stationary labyrinth seal system includes a seal housing having an annular cavity, a plurality of damping devices, and a retaining ring. The damping devices are positioned within the annular cavity and are maintained within the annular cavity by the retaining ring

Sparse Deterministic Approximation of Bayesian Inverse Problems

We present a parametric deterministic formulation of Bayesian inverse problems with input parameter from infinite dimensional, separable Banach spaces. In this formulation, the forward problems are parametric, deterministic elliptic partial differential equations, and the inverse problem is to determine the unknown, parametric deterministic coefficients from noisy observations comprising linear functionals of the solution. We prove a generalized polynomial chaos representation of the posterior density with respect to the prior measure, given noisy observational data. We analyze the sparsity of the posterior density in terms of the summability of the input data's coefficient sequence. To this end, we estimate the fluctuations in the prior. We exhibit sufficient conditions on the prior model in order for approximations of the posterior density to converge at a given algebraic rate, in terms of the number $N$ of unknowns appearing in the parameteric representation of the prior measure. Similar sparsity and approximation results are also exhibited for the solution and covariance of the elliptic partial differential equation under the posterior. These results then form the basis for efficient uncertainty quantification, in the presence of data with noise

Success of Ureteral Stents for Intrinsic Ureteral Obstruction

Purpose: Previous reports suggest a high success rate for retrograde ureteral stenting for intrinsic ureteral obstruction, but few preoperative predictors of success have been offered. We reviewed our experience to look for factors that suggest failure of stents for intrinsic ureteral obstruction. Materials and Methods: We retrospectively reviewed the outcome of retrograde ureteral stent placement for intrinsic ureteral obstruction without concurrent or intended definitive management of the obstruction. Results: Thirty-eight patients treated for intrinsic ureteral obstruction, representing 41 ureteral units (UUs), were monitored for an average of 25.5 months. The overall success rate was 88%. Of the successes, 13 UUs had definitive therapy to permanently remove the cause of obstruction, obstruction resolved in 12 UUs after stent placement, and 11 UUs were managed with indwelling stents. Therapy failed in five UUs, with a median time to failure of 1.9 months. Of the UUs in which failure occurred, three failures were caused by misdiagnosis; in the remaining two, the stent did not correct the obstruction. On univariate analysis, male sex (P = 0.006), increased creatinine level as a presenting symptom (P = 0.002), and more severe preoperative hydronephrosis (P = 0.042) were predictive of failure. Adverse events were low, with complications from stenting occurring on only four of 41 UUs. Conclusion: If initial stent placement was possible, intrinsic ureteral obstruction was managed successfully in 88% of patients. Given high success and minimal complications, retrograde placement of ureteral stents can be performed to treat patients with intrinsic ureteral obstruction. Treatment failure is more likely to occur in men and patients with severe hydronephrosis or an elevated creatinine level.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63109/1/end.2007.0201.pd

Vector meson dominance and the rho meson

We discuss the properties of vector mesons, in particular the rho^0, in the context of the Hidden Local Symmetry (HLS) model. This provides a unified framework to study several aspects of the low energy QCD sector. Firstly, we show that in the HLS model the physical photon is massless, without requiring off field diagonalization. We then demonstrate the equivalence of HLS and the two existing representations of vector meson dominance, VMD1 and VMD2, at both tree level and one loop order. Finally the S matrix pole position is shown to provide a model and process independent means of specifying the rho mass and width, in contrast to the real axis prescription currently used in the Particle Data Group tables.Comment: 18 pages, REVTE

Wild bee and floral diversity co-vary in response to the direct and indirect impacts of land use

Loss of habitat area and diversity poses a threat to communities of wild pollinators and flowering plants in agricultural landscapes. Pollinators, such as wild bees, and insect‐pollinated plants are two groups of organisms that closely interact. Nevertheless, it is still not clear how species richness and functional diversity, in terms of pollination‐relevant traits, of these two groups influence each other and how they respond to land use change. In the present study, we used data from 24 agricultural landscapes in seven European countries to investigate the effect of landscape composition and habitat richness on species richness and functional diversity of wild bees and insect‐pollinated plants. We characterized the relationships between the diversity of bees and flowering plants and identified indirect effects of landscape on bees and plants mediated by these relationships. We found that increasing cover of arable land negatively affected flowering plant species richness, while increasing habitat richness positively affected the species richness and functional diversity of bees. In contrast, the functional diversity of insect‐pollinated plants (when corrected for species richness) was unaffected by landscape composition, and habitat richness showed little relation to bee functional diversity. We additionally found that bee species richness positively affected plant species richness and that bee functional diversity was positively affected by both species richness and functional diversity of plants. The relationships between flowering plant and bee diversity were modulated by indirect effects of landscape characteristics on the biotic communities. In conclusion, our findings demonstrate that landscape properties affect plant and bee communities in both direct and indirect ways. The interconnection between the diversities of wild bees and insect‐pollinated plants increases the risk for parallel declines, extinctions, and functional depletion. Our study highlights the necessity of considering the interplay between interacting species groups when assessing the response of entire communities to land use changes

Plant-pollinator networks in semi-natural grasslands are resistant to the loss of pollinators during blooming of mass-flowering crops

Mass-flowering crops lead to spatial redistributions of pollinators and to transient shortages within nearby semi-natural grasslands, but the impacts on plant–pollinator interactions remain largely unexplored. Here, we characterised which pollinator species are attracted by oilseed rape and how this affected the structure of plant–pollinator networks in nearby grasslands. We surveyed 177 networks from three countries (Germany, Sweden and United Kingdom) in 24 landscapes with high crop cover, and compared them to 24 landscapes with low or no oilseed rape during and after crop blooming. On average 55% of grassland pollinator species were found on the crop, which attracted 8–35% of individuals away from grasslands. However, networks in the grasslands were resistant to these reductions, since mainly abundant and highly mobile species were attracted. Nonetheless, simulations indicated that network structural changes could be triggered if > 50% of individuals were attracted to the crop (a value well-above that found in our study system), which could affect community stability and resilience to further disturbance

Mass-flowering crops dilute pollinator abundance in agricultural landscapes across Europe

Mass-flowering crops (MFCs) are increasingly cultivated and might influence pollinator communities in MFC fields and nearby semi-natural habitats (SNHs). Across six European regions and 2 years, we assessed how landscape-scale cover of MFCs affected pollinator densities in 408 MFC fields and adjacent SNHs. In MFC fields, densities of bumblebees, solitary bees, managed honeybees and hoverflies were negatively related to the cover of MFCs in the landscape. In SNHs, densities of bumblebees declined with increasing cover of MFCs but densities of honeybees increased. The densities of all pollinators were generally unrelated to the cover of SNHs in the landscape. Although MFC fields apparently attracted pollinators from SNHs, in landscapes with large areas of MFCs they became diluted. The resulting lower densities might negatively affect yields of pollinator-dependent crops and the reproductive success of wild plants. An expansion of MFCs needs to be accompanied by pollinator-supporting practices in agricultural landscapes

The impact of over 80 years of land cover changes on bee and wasp pollinator communities in England

Change in land cover is thought to be one of the key drivers of pollinator declines, and yet there is a dearth of studies exploring the relationships between historical changes in land cover and shifts in pollinator communities. Here, we explore, for the first time, land cover changes in England over more than 80 years, and relate them to concurrent shifts in bee and wasp species richness and community composition. Using historical data from 14 sites across four counties, we quantify the key land cover changes within and around these sites and estimate the changes in richness and composition of pollinators. Land cover changes within sites, as well as changes within a 1 km radius outside the sites, have significant effects on richness and composition of bee and wasp species, with changes in edge habitats between major land classes also having a key influence. Our results highlight not just the land cover changes that may be detrimental to pollinator communities, but also provide an insight into how increases in habitat diversity may benefit species diversity, and could thus help inform policy and practice for future land management