bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes to the Appearance of Optical Lightning Flashes Observed From Space According to Thunderstorm Organization and Structure
Authors: Peterson Michael , Rudlosky Scott , Zhang Daile 
Published: February 2020

AbstractOptical lightning observations from space reveal a wide range of flash structure. Lightning imagers such as the Geostationary Lightning Mapper and Lightning Imaging Sensor measure flash appearance by recording transient changes in cloud top illumination. The spatial and temporal optical energy distributions reported by these instruments depend on the physical structure of the flash and the distribution of hydrometeors within the thundercloud that scatter and absorb the optical emissions. This study explores how flash appearance changes according to the scale and organization of the parent thunderstorms with a focus on mesoscale convective systems. Clouds near the storm edge are frequently illuminated by large optical flashes that remain stationary between groups. These flashes appear large because their emissions can reflect off the exposed surfaces of nearby clouds to reach the satellite. Large stationary flashes also occur in small isolated thunderstorms. Optical flashes that propagate horizontally, meanwhile, are most frequently observed in electrified stratiform regions where extensive layered charge structures promote lateral development. Highly radiant “superbolts” occur in two scenarios: embedded within raining stratiform regions or in nonraining boundary/anvil clouds where optical emissions can take a relatively clear path to the satellite.
Connections Between Stratospheric Ozone Concentrations Over the Arctic and Sea Surface Temperatures in the North Pacific
Authors: Liu Meichen , Hu Dingzhu , Zhang Feng 
Published: February 2020

AbstractWe examined the relationship between sea surface temperatures (SSTs) in the North Pacific and the concentration of stratospheric ozone in the northern hemisphere in February–March from 1980 to 2017 using reanalysis and satellite datasets. Our results show that the concentration of stratospheric ozone can be modulated by the principle mode of the North Pacific SSTs—that is, there are negative and zonally asymmetrical ozone anomalies in the Arctic stratosphere, but positive ozone anomalies in the lower stratosphere at mid‐latitudes during the positive phases of the North Pacific SSTs. The North Pacific SST anomalies account for about 20% of the linear variance of ozone concentrations in the lower stratosphere over the Arctic. Negative SST anomalies in the central North Pacific tend to result in a strengthened Western‐Pacific like teleconnection, which favors the propagation of more planetary wavenumber‐1 and ‐2 waves into the stratosphere. The North Pacific SSTs‐related upwelling branch of the Brewer–Dobson circulation in the mid‐latitude stratosphere strengthens, but its downwelling branch in the Arctic stratosphere weakens. This results in decreased ozone anomalies in the lower stratosphere over the Arctic and increased ozone anomalies in the lower stratosphere at mid‐latitudes. The zonally asymmetrical distribution of ozone related to the positive phase of SSTs over the North Pacific may be related to the shifting and strengthening of the stratospheric Arctic vortex.
Toward a Data Assimilation System for Seamless Sea Ice Prediction Based on the AWI Climate Model
Authors: Mu Longjiang , Nerger Lars , Tang Qi , Loza Svetlana N. , Sidorenko Dmitry , Wang Qiang , Semmler Tido , Zampieri Lorenzo , Losch Martin , Goessling Helge F. 
Published: February 2020

AbstractThis paper describes and evaluates the assimilation component of a seamless sea ice prediction system, which is developed based on the fully coupled Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research Climate Model (AWI‐CM, v1.1). Its ocean/ice component with unstructured‐mesh discretization and smoothly varying spatial resolution enables seamless sea ice prediction across a wide range of space and time scales. The model is complemented with the Parallel Data Assimilation Framework to assimilate observations in the ocean/ice component with an Ensemble Kalman Filter. The focus here is on the data assimilation of the prediction system. First, the performance of the system is tested in a perfect‐model setting with synthetic observations. The system exhibits no drift for multivariate assimilation, which is a prerequisite for the robustness of the system. Second, real observational data for sea ice concentration, thickness, drift, and sea surface temperature are assimilated. The analysis results are evaluated against independent in situ observations and reanalysis data. Further experiments that assimilate different combinations of variables are conducted to understand their individual impacts on the model state. In particular, assimilating sea ice drift improves the sea ice thickness estimate, and assimilating sea surface temperature is able to avert a circulation bias of the free‐running model in the Arctic Ocean at middepth. Finally, we present preliminary results obtained with an extended system where the atmosphere is constrained by nudging toward reanalysis data, revealing challenges that still need to be overcome to adapt the ocean/ice assimilation. We consider this system a prototype on the way toward strongly coupled data assimilation across all model components.
Secretin release after Roux-en-Y gastric bypass reveals a population of glucose-sensitive S cells in distal small intestine
Authors: Modvig Ida M. , Andersen Daniel B. , Grunddal Kaare V. , Kuhre Rune E. , Martinussen Christoffer , Christiansen Charlotte B. , Ørskov Cathrine , Larraufie Pierre , Kay Richard G. , Reimann Frank , Gribble Fiona M. , Hartmann Bolette , Bojsen-Møller Kirstine N. , Madsbad Sten , Wewer Albrechtsen Nicolai J. , Holst Jens J. 
Published: February 2020

AbstractObjectivesGastrointestinal hormones contribute to the beneficial effects of Roux-en-Y gastric bypass surgery (RYGB) on glycemic control. Secretin is secreted from duodenal S cells in response to low luminal pH, but it is unknown whether its secretion is altered after RYGB and if secretin contributes to the postoperative improvement in glycemic control. We hypothesized that secretin secretion increases after RYGB as a result of the diversion of nutrients to more distal parts of the small intestine, and thereby affects islet hormone release.MethodsA specific secretin radioimmunoassay was developed, evaluated biochemically, and used to quantify plasma concentrations of secretin in 13 obese individuals before, 1 week after, and 3 months after RYGB. Distribution of secretin and its receptor was assessed by RNA sequencing, mass-spectrometry and in situ hybridization in human and rat tissues. Isolated, perfused rat intestine and pancreas were used to explore the molecular mechanism underlying glucose-induced secretin secretion and to study direct effects of secretin on glucagon, insulin, and somatostatin secretion. Secretin was administered alone or in combination with GLP-1 to non-sedated rats to evaluate effects on glucose regulation.ResultsPlasma postprandial secretin was more than doubled in humans after RYGB (P < 0.001). The distal small intestine harbored secretin expressing cells in both rats and humans. Glucose increased the secretion of secretin in a sodium-glucose cotransporter dependent manner when administered to the distal part but not into the proximal part of the rat small intestine. Secretin stimulated somatostatin secretion (fold change: 1.59,P < 0.05) from the perfused rat pancreas but affected neither insulin (P = 0.2) nor glucagon (P = 0.97) secretion. When administered to rats in vivo, insulin secretion was attenuated and glucagon secretion increased (P = 0.04), while blood glucose peak time was delayed (from 15 to 45 min) and gastric emptying time prolonged (P = 0.004).ConclusionsGlucose-sensing secretin cells located in the distal part of the small intestine may contribute to increased plasma concentrations observed after RYGB. The metabolic role of the distal S cells warrants further studies.
SCFβ-TrCP-mediated degradation of TOP2β promotes cancer cell survival in response to chemotherapeutic drugs targeting topoisomerase II
Authors: Shu Jianfeng , Cui Danrui , Ma Ying , Xiong Xiufang , Sun Yi , Zhao Yongchao 
Published: February 2020

AbstractTopoisomerase II (TOP2)-targeting anticancer chemotherapeutic drugs, termed TOP2 poisons, are widely used and effective in the clinic by stabilizing TOP2-DNA covalent complexes to induce DNA double-strand breaks (DSBs) and ultimately, cause cell death. The stabilized TOP2-DNA complex is known to be degraded by proteasome, whereas the underlying mechanism for instant TOP2β degradation in response to TOP2 poisons and the subsequent biological consequence remain elusive. Here, we reported that TOP2 poison-induced TOP2β degradation is mediated by SCFβ-TrCP ubiquitin ligase. Specifically, DNA damage signal, triggered by teniposide (VM-26) treatment, activates ATM, cooperating with CK1 to phosphorylate TOP2β on Ser1134 and Ser1130, respectively, in a canonical degron motif to facilitate β-TrCP binding and subsequent degradation. Inactivation of ATM, CK1 or SCFβ-TrCP by small molecular inhibitors or genetic knockdown/knockout abrogates TOP2β degradation. Biologically, blockage of TOP2β degradation in combination with VM-26 treatment impairs DNA damage response and repair, leading to an accelerated cell death via apoptosis. Thus, it appears that TOP2β degradation is a cellular defensive mechanism to facilitate the exposure of DSBs to trigger DNA damage response and repair. Collectively, our findings reveal a new strategy to improve the efficacy of TOP2 poisons in combination with small-molecule inhibitors against TOP2β degradation.
Ice Ic without stacking disorder by evacuating hydrogen from hydrogen hydrate
Authors: Komatsu Kazuki , Machida Shinichi , Noritake Fumiya , Hattori Takanori , Sano-Furukawa Asami , Yamane Ryo , Yamashita Keishiro , Kagi Hiroyuki 
Published: February 2020

AbstractWater freezes below 0 °C at ambient pressure ordinarily to ice Ih, with hexagonal stacking sequence. Under certain conditions, ice with a cubic stacking sequence can also be formed, but ideal ice Ic without stacking-disorder has never been formed until recently. Here we demonstrate a route to obtain ice Ic without stacking-disorder by degassing hydrogen from the high-pressure form of hydrogen hydrate, C2, which has a host framework isostructural with ice Ic. The stacking-disorder free ice Ic is formed from C2 via an intermediate amorphous or nano-crystalline form under decompression, unlike the direct transformations occurring in ice XVI from neon hydrate, or ice XVII from hydrogen hydrate. The obtained ice Ic shows remarkable thermal stability, until the phase transition to ice Ih at 250 K, originating from the lack of dislocations. This discovery of ideal ice Ic will promote understanding of the role of stacking-disorder on the physical properties of ice as a counter end-member of ice Ih.
A phosphorylation-based switch controls TAA1-mediated auxin biosynthesis in plants
Authors: Wang Qian , Qin Guochen , Cao Min , Chen Rong , He Yuming , Yang Liyuan , Zeng Zhejun , Yu Yongqiang , Gu Yangtao , Xing Weiman , Tao W. Andy , Xu Tongda 
Published: February 2020

AbstractAuxin determines the developmental fate of plant tissues, and local auxin concentration is precisely controlled. The role of auxin transport in modulating local auxin concentration has been widely studied but the regulation of local auxin biosynthesis is less well understood. Here, we show that TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS (TAA1), a key enzyme in the auxin biosynthesis pathway in Arabidopsis thaliana is phosphorylated at Threonine 101 (T101). T101 phosphorylation status can act as an on/off switch to control TAA1-dependent auxin biosynthesis and is required for proper regulation of root meristem size and root hair development. This phosphosite is evolutionarily conserved suggesting post-translational regulation of auxin biosynthesis may be a general phenomenon. In addition, we show that auxin itself, in part via TRANS-MEMBRANE KINASE 4 (TMK4), can induce T101 phosphorylation of TAA1 suggesting a self-regulatory loop whereby local auxin signalling can suppress biosynthesis. We conclude that phosphorylation-dependent control of TAA1 enzymatic activity may contribute to regulation of auxin concentration in response to endogenous and/or external cues.
Two-stage electro–mechanical coupling of a KV channel in voltage-dependent activation
Authors: Hou Panpan , Kang Po Wei , Kongmeneck Audrey Deyawe , Yang Nien-Du , Liu Yongfeng , Shi Jingyi , Xu Xianjin , White Kelli McFarland , Zaydman Mark A. , Kasimova Marina A. , Seebohm Guiscard , Zhong Ling , Zou Xiaoqin , Tarek Mounir , Cui Jianmin 
Published: February 2020

AbstractIn voltage-gated potassium (KV) channels, the voltage-sensing domain (VSD) undergoes sequential activation from the resting state to the intermediate state and activated state to trigger pore opening via electro–mechanical (E–M) coupling. However, the spatial and temporal details underlying E–M coupling remain elusive. Here, utilizing KV7.1’s unique two open states, we report a two-stage E–M coupling mechanism in voltage-dependent gating of KV7.1 as triggered by VSD activations to the intermediate and then activated state. When the S4 segment transitions to the intermediate state, the hand-like C-terminus of the VSD-pore linker (S4-S5L) interacts with the pore in the same subunit. When S4 then proceeds to the fully-activated state, the elbow-like hinge between S4 and S4-S5L engages with the pore of the neighboring subunit to activate conductance. This two-stage hand-and-elbow gating mechanism elucidates distinct tissue-specific modulations, pharmacology, and disease pathogenesis of KV7.1, and likely applies to numerous domain-swapped KVchannels.
Tropical cyclone rainbands can trigger meteotsunamis
Authors: Shi Luming , Olabarrieta Maitane , Nolan David S. , Warner John C. 
Published: February 2020

AbstractTropical cyclones are one of the most destructive natural hazards and much of the damage and casualties they cause are flood-related. Accurate characterization and prediction of total water levels during extreme storms is necessary to minimize coastal impacts. While meteotsunamis are known to influence water levels and to produce severe consequences, their impacts during tropical cyclones are underappreciated. This study demonstrates that meteotsunami waves commonly occur during tropical cyclones, and that they can contribute significantly to total water levels. We use an idealized coupled ocean–atmosphere–wave numerical model to analyze tropical cyclone-induced meteotsunami generation and propagation mechanisms. We show that the most extreme meteotsunami events are triggered by inherent features of the structure of tropical cyclones: inner and outer spiral rainbands. While outer distant spiral rainbands produce single-peak meteotsunami waves, inner spiral rainbands trigger longer lasting wave trains on the front side of the tropical cyclones.
Deep Analysis of Residue Constraints (DARC): identifying determinants of protein functional specificity
Authors: Tondnevis Farzaneh , Dudenhausen Elizabeth E. , Miller Andrew M. , McKenna Robert , Altschul Stephen F. , Bloom Linda B. , Neuwald Andrew F. 
Published: February 2020

AbstractProtein functional constraints are manifest as superfamily and functional-subgroup conserved residues, and as pairwise correlations. Deep Analysis of Residue Constraints (DARC) aids the visualization of these constraints, characterizes how they correlate with each other and with structure, and estimates statistical significance. This can identify determinants of protein functional specificity, as we illustrate for bacterial DNA clamp loader ATPases. These load ring-shaped sliding clamps onto DNA to keep polymerase attached during replication and contain one δ, three γ, and one δ’ AAA+ subunits semi-circularly arranged in the order δ-γ1-γ2-γ3-δ’. Only γ is active, though both γ and δ’ functionally influence an adjacent γ subunit. DARC identifies, as functionally-congruent features linking allosterically the ATP, DNA, and clamp binding sites: residues distinctive of γ and of γ/δ’ that mutually interact in trans, centered on the catalytic base; several γ/δ’-residues and six γ/δ’-covariant residue pairs within the DNA binding N-termini of helices α2 and α3; and γ/δ’-residues associated with the α2 C-terminus and the clamp-binding loop. Most notable is a trans-acting γ/δ’ hydroxyl group that 99% of other AAA+ proteins lack. Mutation of this hydroxyl to a methyl group impedes clamp binding and opening, DNA binding, and ATP hydrolysis—implying a remarkably clamp-loader-specific function.
Boundary and vulnerability estimation of the internal borderzone using ischemic stroke lesion mapping
Authors: Grange Sylvain , Grange Rémi , Garnier Pierre , Varvat Jérôme , Marinescu Doina , Barral Fabrice-Guy , Boutet Claire , Schneider Fabien C. 
Published: February 2020

AbstractDistinction between deep and superficial middle cerebral artery (MCA) territories and their junctional vascular area (the internal borderzone or IBZ) constitutes a predictor of stroke patient outcome. However, the IBZ boundaries are not well-defined because of substantial anatomical variance. Here, we built a statistical estimate of the IBZ and tested its vulnerability to ischemia using an independent sample. First, we used delineated lesions of 122 patients suffering of chronic ischemic stroke grouped in deep, superficial and territorial topographies and statistical comparisons to generate a probabilistic estimate of the IBZ. The IBZ extended from the insular cortex to the internal capsule and the anterior part of the caudate nucleus head. The IBZ showed the highest lesion frequencies (~30% on average across IBZ voxels) in our chronic stroke patients but also in an independent sample of 87 acute patients. Additionally, the most important apparent diffusion coefficient reductions (−6%), which reflect stroke severity, were situated within our IBZ estimate. The IBZ was most severely injured in case of a territorial infarction. Then, our results are in favour of an increased IBZ vulnerability to ischemia. Moreover, our probabilistic estimates of deep, superficial and IBZ regions can help the everyday spatial classification of lesions.
Three members of the yeast N-BAR proteins family form heterogeneous lattices in vivo and interact differentially with two RabGAP proteins
Authors: Prigent Magali , Chaillot Julien , Tisserand Hélène , Boy-Marcotte Emmanuelle , Cuif Marie-Hélène 
Published: February 2020

AbstractThe yeast N-BAR (Bin/Amphiphysin/Rvs167) protein Rvs167 is recruited by the Rab GTPase Activating Proteins (RabGAP) Gyp5 and Gyl1 to the tip of small buds to act in exocytosis. Investigating other N-BAR proteins involved in Gyp5/Gyl1/Rvs167 complexes, we found that Rvs161, an Rvs167 paralog, is absent from the complexes formed at the tip of small buds. Immunoprecipitation and Bimolecular Fluorescence Complementation (BiFC) analysis show that both Rvs167 and Rvs161 interact in vivo with Gvp36, an N-BAR protein. Rvs167 molecules also interact independently of Rvs161 and Gvp36. Rvs167/Rvs167 and Rvs167/Gyp5 interactions predominate over other combinations at the tip of small buds, suggesting that N-BAR lattices enriched in Rvs167 molecules form at these sites. By combining BiFC with markers specific to each organelle, we analyzed systematically in living cells the locations of the BiFC signals generated by combinations of the three N-BAR proteins. We show that the BiFC signals differ according to organelle and cell site, strongly suggesting heterogeneity in the composition of N-BAR protein lattices in vivo. Our results reveal that the organization of N-BAR protein lattices in vivo is complex and are consistent with N-BAR proteins forming various types of dimers and lattices of variable composition.
Identification of Quantitative Trait Loci Controlling Ethylene Production in Germinating Seeds in Maize (Zea mays L.)
Authors: Kong Dongdong , Fu Xiuyi , Jia Xiaohui , Wang Wenhui , Li Yi , Li Jiansheng , Yang Xiaohong , Ju Chuanli 
Published: February 2020

AbstractPlant seed germination is a crucial developmental event that has significant effects on seedling establishment and yield production. This process is controlled by multiple intrinsic signals, particularly phytohormones. The gaseous hormone ethylene stimulates seed germination; however, the genetic basis of ethylene production in maize during seed germination remains poorly understood. In this study, we quantified the diversity of germination among 14 inbred lines representing the parental materials corresponding to multiple recombinant inbred line (RIL) mapping populations. Quantitative trait loci (QTLs) controlling ethylene production were then identified in germinating seeds from an RIL population constructed from two parental lines showing differences in both germination speed and ethylene production during germination. To explore the possible genetic correlations of ethylene production with other traits, seed germination and seed weight were evaluated using the same batch of samples. On the basis of high-density single nucleotide polymorphism-based genetic linkage maps, we detected three QTLs for ethylene production in germinating seeds, three QTLs for seed germination, and four QTLs for seed weight, with each QTL explaining 5.8%–13.2% of the phenotypic variation of the trait. No QTLs were observed to be co-localized, suggesting that the genetic bases underlying the three traits are largely different. Our findings reveal three chromosomal regions responsible for ethylene production during seed germination, and provide a valuable reference for the future investigation of the genetic mechanism underlying the role of the stress hormone ethylene in maize germination control under unfavourable external conditions.
Effect of High Calorie Diet on Intestinal Flora in LPS-Induced Pneumonia Rats
Authors: Bai Chen , Liu Tiegang , Xu Jingnan , Ma Xueyan , Huang Ling , Liu Shaoyang , Yu He , Chen Jianxin , Gu Xiaohong 
Published: February 2020

AbstractIntestinal flora plays an important role in inflammatory response to systemic or local organs of its host. High calorie diet has been shown to aggravate the condition of pneumonia and delay recovery, especially in children. However, the underlying mechanisms remain unclear. This study placed SPF rats in a conventional environment, high calorie diet or LPS atomization was performed respectively or combined. Analysis of high-throughput sequencing of intestinal content combined with animal weight, organ index, serum inflammatory factors indicators and bioinformatics found that after pulmonary infection combined with a high-calorie diet, rats showed significant changes such as weight loss and increased lung weight index, and their lung and intestinal tissues showed more obvious inflammatory changes. And its gut flora structure suggests, the abundance of Leuconostocaceae in significantly reduced; abundance of Staphylococcus, Planococcaceae, Staphylococcus, Staphylococcaceae, Bacillales, Gemellales and Aerococcus significant increased. The study showed that high calorie diet and LPS atomization synergistically promoted pneumonia process in rat pups, which is related to changes in structure of intestinal flora. It is worth noting that pneumonia rats fed by convention diet also causing intestinal flora imbalance.