NAD kinase regulates the size of the NADPH pool and insulin secretion in pancreatic β-cells

NADPH is an important component of the antioxidant defense system and a proposed mediator in glucose-stimulated insulin secretion (GSIS) from pancreatic β-cells. An increase in the NADPH/NADP(+) ratio has been reported to occur within minutes following the rise in glucose concentration in β-cells. However, 30 min following the increase in glucose, the total NADPH pool also increases through a mechanism not yet characterized. NAD kinase (NADK) catalyzes the de novo formation of NADP(+) by phosphorylation of NAD(+). NAD kinases have been shown to be essential for redox regulation, oxidative stress defense, and survival in bacteria and yeast. However, studies on NADK in eukaryotic cells are scarce, and the function of this enzyme has not been described in β-cells. We employed INS-1 832/13 cells, an insulin-secreting rat β-cell line, and isolated rodent islets to investigate the role of NADK in β-cell metabolic pathways. Adenoviral-mediated overexpression of NADK resulted in a two- to threefold increase in the total NADPH pool and NADPH/NADP(+) ratio, suggesting that NADP(+) formed by the NADK-catalyzed reaction is rapidly reduced to NADPH via cytosolic reductases. This increase in the NADPH pool was accompanied by an increase in GSIS in NADK-overexpressing cells. Furthermore, NADK overexpression protected β-cells against oxidative damage by the redox cycling agent menadione and reversed menadione-mediated inhibition of GSIS. Knockdown of NADK via shRNA exerted the opposite effect on all these parameters. These data suggest that NADK kinase regulates intracellular redox and affects insulin secretion and oxidative defense in the β-cell.     

Core saccharide dependence of sialyl Lewis X biosynthesis

The sialyl-Lewis X (SLe^x) determinant is important in leukocyte extravasation, metastasis and bacterial adhesion. The role of the protein, N-glycan and O-glycan core structures for the biosynthesis of SLe^x in vivo by fucosyltransferases (FucTs) is not known. Immunoglobulin G (IgG) Fc fusion proteins of α₁-acid glycoprotein (AGP), P-selectin glycoprotein ligand-1 (PSGL-1) or CD43 were used to probe the specificity of FucT-III-VII expressed alone in 293T and COS cells or together with O-glycan core enzymes in Chinese hamster ovary (CHO)-K1 cells. Western blotting with the monoclonal antibodies CSLEX and KM93 showed that FucT-III and V-VII produced SLe^x on core 2 in CHO cells. Only FucT-V, -VI and, with low activity, -VII worked on core 3 on CD43/IgG, but no SLe^x was detected with CSLEX on PSGL-1/IgG with core 3. KM93 stained SLe^x on core 2, but was not reactive with SLe^x on core 3. FucT-III, V-VII made SLe^x on N-glycans of AGP/IgG in CHO, but not in COS and 293T cells, even though the same FucTs could make SLe^x on CD43/IgG and PSGL-1/IgG in these cells. Our results define the specificities of FucT-III-VII in SLe^x biosynthesis on O-glycans with different core structures and the fine specificity of the widely used anti-SLe^x monoclonal antibody, KM93.     

Understanding the Role of Cesium and Rubidium Additives in Perovskite Solar Cells: Trap States,Charge Transport,and Recombination

Adding cesium (Cs) and rubidium (Rb) cations to FA_0.83MA_0.17Pb(I_0.83Br_0.17)₃ hybrid lead halide perovskites results in a remarkable improvement in solar cell performance, but the origin of the enhancement has not been fully understood yet. In this work, time‐of‐flight, time‐resolved microwave conductivity, and thermally stimulated current measurements are performed to elucidate the impact of the inorganic cation additives on the trap landscape and charge transport properties within perovskite solar cells. These complementary techniques allow for the assessment of both local features within the perovskite crystals and macroscopic properties of films and full devices. Strikingly, Cs‐incorporation is shown to reduce the trap density and charge recombination rates in the perovskite layer. This is consistent with the significant improvements in the open‐circuit voltage and fill factor of Cs‐containing devices. By comparison, Rb‐addition results in an increased charge carrier mobility, which is accompanied by a minor increase in device efficiency and reduced current–voltage hysteresis. By mixing Cs and Rb in quadruple cation (Cs‐Rb‐FA‐MA) perovskites, the advantages of both inorganic cations can be combined. This study provides valuable insights into the role of these additives in multiple‐cation perovskite solar cells, which are essential for the design of high‐performance devices.     

Response of the European grapevine moth Lobesia botrana to somatosensory‐active volatiles emitted by the non‐host plant Perilla frutescens

The European grapevine moth Lobesia botrana Denis & Schiffermüller (Lepidoptera: Tortricidae) is a major pest on grapes worldwide. Attempts to develop control methods for this pest based on grape kairomones demonstrate limited success and studies indicate that a major limiting factor is overlap between synthetic kairomones and background odours in the vineyard. Behaviourally active compounds from non‐host plants may thus represent an effective alternative for monitoring and control methods. Extracts from food plants (i.e. from capsicum, garlic and peppermint, which elicit the so‐called somatosensory sensation) are traditionally used in agriculture for the control of pest insects. Among those plants, Perilla frutescens L. (Lamiales: Lamiaceae), native of Asia, contains compounds activating sensory ion channels in mammals, which are known to be involved in the perception of somatosensory compounds and are expressed in tortricid moth antennae. In the present study, in search of non‐host volatiles with potential application in pest control, essential oil metabolites isolated from P. frutescens are screened for biological activity on the olfactory system of L. botrana. The compounds (S)‐(?)‐perillaldehyde and isoegomaketone, which are released from different P. frutescens varieties, are identified by gas chromatography‐coupled electroantennographic detection. In a dual‐choice oviposition test, females show a preference for a combination of host odours and perillaldehyde, preferring this over a host‐plant odour bouquet alone. In Y‐tube olfactometer assays, virgin males show a higher level of activity in the presence of isoegomaketone, even if not significantly responsive to the compound.     

Microclimate variability in alpine ecosystems as stepping stones for non‐native plant establishment above their current elevational limit

Alpine environments are currently relatively free from non‐native plant species, although their presence and abundance have recently been on the rise. It is however still unclear whether the observed low invasion levels in these areas are due to an inherent resistance of the alpine zone to invasions or whether an exponential increase in invasion is just a matter of time. Using a seed‐addition experiment on north‐ and south‐facing slopes (cf. microclimatic gradient) on two mountains in subarctic Sweden, we tested the establishment of six non‐native species at an elevation above their current distribution limits and under experimentally enhanced anthropogenic pressures (disturbance, added nutrients and increased propagule pressure). We found a large microclimatic variability in cumulative growing degree days (GDD) (range = 500.77°C, SD = 120.70°C) due to both physiographic (e.g. aspect) and biophysical (e.g. vegetation cover) features, the latter being altered by the experimental disturbance. Non‐native species establishment and biomass production were positively correlated with GDD along the studied microclimatic gradient. However, even though establishment on the north‐facing slopes caught up with that on the south‐facing slopes throughout the growing season, biomass production was limited on the north‐facing slopes due to a shorter growing season. On top of this microclimatic effect, all experimentally imposed anthropogenic factors enhanced non‐native species success. The observed microclimatic effect indicates a potential for non‐native species to use warm microsites as stepping stones for their establishment towards the cold end of the gradient. Combined with anthropogenic pressures this result suggests an increasing risk for plant invasion in cold ecosystems, as such stepping stones in alpine ecosystems are likely to be more common in a future that will combine a warming climate with persistent anthropogenic pressures.     

Implementation of Transportation Distance for Analyzing FLIM and FRET Experiments

Analysis of fluorescence lifetime imaging microscopy (FLIM) and Förster resonance energy transfer (FRET) experiments in living cells is usually based on mean lifetimes computations. However, these mean lifetimes can induce misinterpretations. We propose in this work the implementation of the transportation distance for FLIM and FRET experiments in vivo. This non-fitting indicator, which is easy to compute, reflects the similarity between two distributions and can be used for pixels clustering to improve the estimation of the FRET parameters. We study the robustness and the discriminating power of this transportation distance, both theoretically and numerically. In addition, a comparison study with the largely used mean lifetime differences is performed. We finally demonstrate practically the benefits of the transportation distance over the usual mean lifetime differences for both FLIM and FRET experiments in living cells.     

Clinical Characteristics of 582 Patients with Uveal Melanoma in China

Objective

To assess clinical characteristics, treatment and survival of patients with uveal melanoma in China.

Methods

The retrospective study included all patients with malignant uveal melanoma who were consecutively examined in the study period from January 2005 and June 2015 in the Beijing Tongren hospital.

Results

The mean age of the 582 patients (295(50.7%) women) was 44.6±12.6 years (range:5–77 years). The tumors were located most often in the superior temporal region (in 117(21.5%) patients) and least common in the inferior region (in 31(5.7%) patients). In 548(94.2%) patients, the tumors were located in the choroid, in 33(5.7%) patients in the ciliary body, and in one (0.2%) patient in the iris. Treatment included episcleral brachytherapy (415(71.3%) patients), local tumor resection (48(8.2%) patients) and primary enucleation (119(20.4%) patients). In 53 individuals out of the 415 patients with primary brachytherapy, episcleral brachytherapy was followed by enucleation, due to an increasing tumor size or due to uncontrolled neovascular glaucoma. Median follow-up time was of 30 months (range: 1–124 months; mean: 34.8 ± 24.4 months). Overall survival rate at 5 and 10 years was of 92.7% and 85.1%. Younger age (P = 0.017), tumor location in the nasal meridian(P = 0.004), smaller tumor size (P<0.001), hemispheric tumor shape (P = 0.025), histological tumor cell type (spindle-cell type versus epitheloid cell type;P = 0.014), and type of treatment (episcleral brachytherapy versus local tumor resection and versus primary enucleation; P<0.001) were significantly associated with the overall survival in univariate analysis, while in multivariate analysis only smaller tumor size was significantly (P<0.001; RR: 4.75; 95% confidence interval:2.11,10.7) associated with better overall survival.

Conclusions

In this study on clinical characteristics of uveal melanoma of a larger group of patients from China, the onset age was considerably younger and survival rate better than in studies from Western countries. Tumor size was the most significant factor for survival.