bluuebunny/crossref_metadata_2025_split huggingface dataset:
Trajectory of Topsoil Nitrogen Transformations Along a Thermo‐Erosion Gully on the Tibetan Plateau
Authors: Mao Chao , Kou Dan , Wang Guanqin , Peng Yunfeng , Yang Guibiao , Liu Futing , Zhang Jinbo , Yang Yuanhe 
Published: April 2019

AbstractPermafrost thaw, especially thermokarst formation, that is, ground collapse due to thawing of ice‐rich permafrost, is expected to alter soil gross nitrogen (N) transformations, which can regulate plant productivity and ecosystem carbon cycle. However, it remains unclear how thermokarst formation modifies soil N processes in permafrost ecosystems. Here 15N pool dilution techniques were used to evaluate changes in topsoil gross N transformations during various thaw stages (early, middle, and late stages) along a thermo‐erosion gully on the Tibetan Plateau. Structural equation modeling was then conducted to explore the relative importance of biotic and abiotic factors in affecting soil gross N transformations. The results showed that topsoil gross N mineralization (GNM) decreased at the three stages, reflecting declined inorganic N production after permafrost collapse. In contrast, topsoil gross nitrification increased only during the early stage. Additionally, the ratio of microbial N immobilization to GNM was enhanced during the middle and late stages, indicating a stronger microbial N limitation after thermokarst formation. The structural equation modeling analysis revealed that soil moisture played an important role in modulating gross N transformations. For GNM, decreased soil moisture had inhibiting effects via regulating the microbial biomass, microbial community, and enzyme activities along the thaw sequence. For gross nitrification, declined soil moisture exerted facilitating effects directly by improving oxygen availability and indirectly by modulating the abundances of ammonia‐oxidizing archaea and bacteria during the early stage. Overall, these results demonstrated that thermokarst formation altered soil N processes, potentially triggering interactions between ecosystem N and carbon cycles after permafrost thaw.
Southward Displacement of the North Atlantic Subtropical Gyre Circulation System During North Atlantic Cold Spells
Authors: Reißig S. , Nürnberg D. , Bahr A. , Poggemann D.‐W. , Hoffmann J. 
Published: April 2019

AbstractDuring times of deglacial Atlantic Meridional Overturning Circulation (AMOC) perturbations, the tropical Atlantic experienced considerable warming at subsurface levels. Coupled ocean‐atmosphere simulations corroborate the tight teleconnection between the tropical Atlantic and climate change at high northern latitudes but still underestimate the relevance of the subsurface North Atlantic subtropical gyre (STG) for heat and salt storage and its sensitivity to rapid climatic change. We here reconstruct vertical and lateral temperature and salinity gradients in the tropical west Atlantic and the Caribbean over the last 30 kyr, based on planktic deep and shallow dwelling foraminiferal Mg/Ca and δ18O records. The rapid and large‐amplitude subsurface changes illustrate a dynamic STG associated with abrupt shifts of North Atlantic hydrographic and atmospheric regimes. During full glacial conditions, the STG has been shifted southward while intensified Ekman downwelling associated to strengthened trade winds fostered the formation of warm and saline salinity maximum water (SMW). The southward propagation of SMW was facilitated by the glacially eastward deflected North Brazil Current. During periods of significant AMOC perturbations (Heinrich Stadials 1 and the Younger Dryas), extreme subsurface warming by ~6 °C led to diminished lateral subsurface temperature gradients. Coevally, a deep thermocline suggests that SMW fully occupied the subsurface tropical west Atlantic and that the STG reached its southernmost position. During the Holocene, modern‐like conditions gradually developed with the northward retreat of SMW and the development of a strong thermocline ridge between the Subtropical Gyre and the tropical west Atlantic.
Fresh Submarine Groundwater Discharge to the Near‐Global Coast
Authors: Zhou YaoQuan , Sawyer Audrey H. , David Cédric H. , Famiglietti James S. 
Published: April 2019

AbstractThe flow of fresh groundwater to the ocean through the coast (fresh submarine groundwater discharge or fresh SGD) plays an important role in global biogeochemical cycles and coastal water quality. In addition to delivering dissolved elements from land to sea, fresh SGD forms a natural barrier against salinization of coastal aquifers. Here we estimate groundwater discharge rates through the near‐global coast (60°N to 60°S) at high resolution using a water budget approach. We find that tropical coasts export more than 56% of all fresh SGD, while midlatitude arid regions export only 10%. Fresh SGD rates from tectonically active margins (coastlines along tectonic plate boundaries) are also significantly greater than passive margins, where most field studies have been focused. Active margins combine rapid uplift and weathering with high rates of fresh SGD and may therefore host exceptionally large groundwater‐borne solute fluxes to the coast.
On the Origin of Perpendicular Ion Anisotropy Inside Dipolarizing Flux Bundles
Authors: Zhou Xu‐Zhi , Xu Yan , Runov Andrei , Liu Jiang , Artemyev Anton V. , Angelopoulos Vassilis , Birn Joachim , Yao Zhonghua , Pan Dong‐Xiao , Zong Qiu‐Gang 
Published: April 2019

AbstractPerpendicular anisotropy of suprathermal ions, observed inside some of the dipolarizing flux bundles (DFBs) in the magnetotail plasma sheet, have been attributed to successive, betatron‐type accelerations during the DFB entry of ambient ions. It has been unclear, however, where and how these ions enter the DFBs. The proposed locations include the DFB flanks where cross‐tail drifting ions are picked up, and the DFB leading edge with sharp magnetic field gradient (the dipolarization front, DF). Here we examine the latter scenario, based on a simplistic, test particle approach, to predict the preferred conditions for the appearance of the DFB ion anisotropy. Our model predicts that the ion anisotropy would be stronger at locations closer to the neutral sheet and would appear preferentially in the DFB dawnside and central sectors rather than the duskside sector. We also predict that the ion anisotropy would more likely be observed in DFBs with higher propagation speeds. These properties can be understood in our model by the dawnward drift of ions during their DF penetration (attributed to the large magnetic gradient). To examine these predictions, we carry out a statistical survey based on observations from the THEMIS (Time History of Events and Macroscale Interactions during Substorms) mission, to show a clear dependence of the ion anisotropy on spacecraft location and the DFB propagation speed. These findings, therefore, are consistent with the scenario that the perpendicular ion anisotropy originates from the ion acceleration and penetration across sharp DFs.
Intracellular Burkholderia Symbionts induce extracellular secondary infections; driving diverse host outcomes that vary by genotype and environment
Authors: Khojandi Niloufar , Haselkorn Tamara S , Eschbach Madison N , Naser Rana A , DiSalvo Susanne 
Published: April 2019

Abstract
Symbiotic associations impact and are impacted by their surrounding ecosystem. The association between Burkholderia bacteria and the soil amoeba Dictyostelium discoideum is a tractable model to unravel the biology underlying symbiont-endowed phenotypes and their impacts. Several Burkholderia species stably associate with D. discoideum and typically reduce host fitness in food-rich environments while increasing fitness in food-scarce environments. Burkholderia symbionts are themselves inedible to their hosts but induce co-infections with secondary bacteria that can serve as a food source. Thus, Burkholderia hosts are “farmers” that carry food bacteria to new environments, providing a benefit when food is scarce. We examined the ability of specific Burkholderia genotypes to induce secondary co-infections and assessed host fitness under a range of co-infection conditions and environmental contexts. Although all Burkholderia symbionts intracellularly infected Dictyostelium, we found that co-infections are predominantly extracellular, suggesting that farming benefits are derived from extracellular infection of host structures. Furthermore, levels of secondary infection are linked to conditional host fitness; B. agricolaris infected hosts have the highest level of co-infection and have the highest fitness in food-scarce environments. This study illuminates the phenomenon of co-infection induction across Dictyostelium associated Burkholderia species and exemplifies the contextual complexity of these associations.
Connected partner-switches control the life style of Pseudomonas aeruginosa through RpoS regulation
Authors: Bouillet Sophie , Ba Moly , Houot Laetitia , Iobbi-Nivol Chantal , Bordi Christophe 
Published: April 2019

AbstractBiofilm formation is a complex process resulting from the action of imbricated pathways in response to environmental cues. In this study, we showed that biofilm biogenesis in the opportunistic pathogenPseudomonas aeruginosadepends on the availability of RpoS, the sigma factor regulating the general stress response in bacteria. Moreover, it was demonstrated that RpoS is post-translationally regulated by the HsbR-HsbA partner switching system as has been demonstrated for its CrsR-CrsA homolog inShewanella oneidensis. Finally, it was established that HsbA, the anti-sigma factor antagonist, has a pivotal role depending on its phosphorylation state since it binds HsbR, the response regulator, when phosphorylated and FlgM, the anti-sigma factor of FliA, when non-phosphorylated. The phosphorylation state of HsbA thus drives the switch between the sessile and planktonic way of life ofP.aeruginosaby driving the release or the sequestration of one or the other of these two sigma factors.
Airway surface liquid acidification initiates host defense abnormalities in Cystic Fibrosis
Authors: Simonin Juliette , Bille Emmanuelle , Crambert Gilles , Noel Sabrina , Dreano Elise , Edwards Aurélie , Hatton Aurélie , Pranke Iwona , Villeret Bérengère , Cottart Charles-Henry , Vrel Jean-Patrick , Urbach Valérie , Baatallah Nesrine , Hinzpeter Alexandre , Golec Anita , Touqui Lhousseine , Nassif Xavier , Galietta Luis J. V , Planelles Gabrielle , Sallenave Jean-Michel , Edelman Aleksander , Sermet-Gaudelus Isabelle 
Published: April 2019

AbstractCystic fibrosis (CF) is caused by defective Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein. Morbidity is mainly due to early airway infection. We hypothesized that S. aureus clearance during the first hours of infection was impaired in CF human Airway Surface Liquid (ASL) because of a lowered pH. The ASL pH of human bronchial epithelial cell lines and primary respiratory cells from healthy controls (WT) and patients with CF was measured with a pH microelectrode. The antimicrobial capacity of airway cells was studied after S. aureus apical infection by counting surviving bacteria. ASL was significantly more acidic in CF than in WT respiratory cells. This was consistent with a defect in bicarbonate secretion involving CFTR and SLC26A4 (pendrin) and a persistent proton secretion by ATP12A. ASL demonstrated a defect in S. aureus clearance which was improved by pH normalization. Pendrin inhibition in WT airways recapitulated the CF airway defect and increased S. aureus proliferation. ATP12A inhibition by ouabain decreased bacterial proliferation. Antimicrobial peptides LL-37 and hBD1 demonstrated a pH-dependent activity. Normalizing ASL pH might improve innate airway defense in newborns with CF during onset of S. aureus infection. Pendrin activation and ATP12A inhibition could represent novel therapeutic strategies to normalize pH in CF airways.
Innovation in alternate mulch with straw and plastic management bolsters yield and water use efficiency in wheat-maize intercropping in arid conditions
Authors: Yin Wen , Fan Zhilong , Hu Falong , Yu Aizhong , Zhao Cai , Chai Qiang , Coulter Jeffrey A. 
Published: April 2019

AbstractIn arid regions, higher irrigation quota for conventional farming causes substantial conflict between water supply and demand for crop production. Innovations in cropping systems are needed to alleviate this issue. A field experiment was conducted in northwestern China to assess whether straw and plastic managements in wheat/maize intercropping could alleviate these issues. Integrating no tillage with two-year plastic and straw mulching (NTMI2) improved grain yields by 13.8–17.1%, compared to conventional tillage without straw residue and annual new plastic mulching (CTI). The NTMI2 treatment reduced soil evaporation by 9.0–17.3% and the proportion of evaporation to evapotranspiration (E/ET) by 8.6–17.5%, compared to CTI. The NTMI2 treatment weakened wheat competition of soil moisture from maize strip during wheat growth period, and enhanced wheat compensation of soil moisture for maize growth after wheat harvest, compared with CTI. Thus, soil water movement potential of NTMI2 was lowest during wheat growth period, but it was highest during maize-independent growth stage after wheat harvest. The NTMI2 treatment increased evapotranspiration before maize silking, decreased from maize silking to early-filling stage, and increased after the early-filling stage of maize, this effectively coordinated water demand contradiction of intercrops at early and late stages. The NTMI2 treatment improved WUE by 12.4–17.2%, compared with CTI. The improved crop yields and WUE was attributed to the coordinated water competition and compensation, and the decreased soil evaporation and E/ET.
Inter-generational resemblance of methylation levels at circadian genes and associations with phenology in the barn swallow
Authors: Saino Nicola , Albetti Benedetta , Ambrosini Roberto , Caprioli Manuela , Costanzo Alessandra , Mariani Jacopo , Parolini Marco , Romano Andrea , Rubolini Diego , Formenti Giulio , Gianfranceschi Luca , Bollati Valentina 
Published: April 2019

AbstractRegulation of gene expression can occur via epigenetic effects as mediated by DNA methylation. The potential for epigenetic effects to be transmitted across generations, thus modulating phenotypic variation and affecting ecological and evolutionary processes, is increasingly appreciated. However, the study of variation in epigenomes and inter-generational transmission of epigenetic alterations in wild populations is at its very infancy. We studied sex- and age-related variation in DNA methylation and parent-offspring resemblance in methylation profiles in the barn swallows. We focused on a class of highly conserved ‘clock’ genes (clock, cry1, per2, per3, timeless) relevant in the timing of activities of major ecological importance. In addition, we considerably expanded previous analyses on the relationship between methylation at clock genes and breeding date, a key fitness trait in barn swallows. We found positive assortative mating for methylation at one clocklocus. Methylation varied between the nestling and the adult stage, and according to sex. Individuals with relatively high methylation as nestlings also had high methylation levels when adults. Extensive parent-nestling resemblance in methylation levels was observed. Occurrence of extra-pair fertilizations allowed to disclose evidence hinting at a prevalence of paternal germline or sperm quality effects over common environment effects in generating father-offspring resemblance in methylation. Finally, we found an association between methylation at the clock poly-Q region, but not at otherloci, and breeding date. We thus provided evidence for sex-dependent variation and the first account of parent-offspring resemblance in methylation in any wild vertebrate. We also showed that epigenetics may influence phenotypic plasticity of timing of life cycle events, thus having a major impact on fitness.
Binucleation of male accessory gland cells in the common bed bug Cimex lectularius
Authors: Takeda Koji , Yamauchi Jun , Miki Aoi , Kim Daeyun , Leong Xin-Yeng , Doggett Stephen L. , Lee Chow-Yang , Adachi-Yamada Takashi 
Published: April 2019

AbstractThe insect male accessory gland (MAG) is an internal reproductive organ responsible for the synthesis and secretion of seminal fluid components, which play a pivotal role in the male reproductive strategy. In many species of insects, the effective ejaculation of the MAG products is essential for male reproduction. For this purpose, the fruit fly Drosophila has evolved binucleation in the MAG cells, which causes high plasticity of the glandular epithelium, leading to an increase in the volume of seminal fluid that is ejaculated. However, such a binucleation strategy has only been sporadically observed in Dipteran insects, including fruit flies. Here, we report the discovery of binucleation in the MAG of the common bed bug, Cimex lectularius, which belongs to hemimetabolous Hemiptera phylogenetically distant from holometabolous Diptera. In Cimex, the cell morphology and timing of synchrony during binucleation are quite different from those of Drosophila. Additionally, in Drosophila, the position of the two nuclei in the adult stage changes as a result of the mating history or the nutrient conditions; however, it remains stable in Cimex. These differences suggest that binucleation in the Cimex MAG plays a unique role in the male reproductive system that is distinct from that of Drosophila.
Short-term detection of volcanic unrest at Mt. Etna by means of a multi-station warning system
Authors: Spampinato Salvatore , Langer Horst , Messina Alfio , Falsaperla Susanna 
Published: April 2019

AbstractEarly-warning assessment of a volcanic unrest requires that accurate information from monitoring is continuously gathered before volcanic activity starts. Seismic data are an optimal source of such information, overcoming safety problems due to dangerous conditions for field surveys or cloud cover that may hinder visibility. We designed a multi-station warning system based on the classification of patterns of the background seismic radiation, so-called volcanic tremor, by using Self-Organizing Maps (SOM) and fuzzy clustering. The classifier automatically detects patterns that are typical footprints of volcanic unrest. The issuance of the SOM colors on DEM allows their geographical visualization according to the stations of detection; this spatial location makes it possible to infer areas potentially impacted by eruptive phenomena. Tested at Mt. Etna (Italy), the classifier forecasted in hindsight patterns associated with fast-rising magma (typical of lava fountains) as well as a relatively long lead time of the outburst (lava flows from eruptive fractures). Receiver Operating Characteristics (ROC) curves gave an Area Under the Curve (AUC) ∼0.8 indicative of a good detection accuracy that cannot be achieved from a mere random choice.
Prediction of Fractures in Coal Seams with Multi-component Seismic Data
Authors: Li Mengqi , Lu Jun , Xiong Shu 
Published: April 2019

AbstractFractures that develop in coal seams threaten safety in many ways, but they can be predicted using fracture parameters derived from seismic data. However, the post-stack split shear waves are difficult to thoroughly separate by Alford rotation due to wavefield mixing. We propose a method of predicting fractures in a coal seam using multi-component seismic data, which was applied to coal seam 13-1 of the Huainan coalfield, China. We employed the Alford rotation to separate the split PS-waves (P-to-S converted waves) and perform interlayer travel-time inversion of the fast shear waves using geophysical logs, rock-physics parameters, and tunnel-excavation information as constraints. However, post-stack wavefield mixing of the coal seam interfered with the Alford rotation of the real post-stack seismic data. Therefore, we only performed the Alford rotation on radial and transverse component post-stack sections to derive fracture azimuths, which were then applied to the pre-stack separation of the split PS-waves. Using joint PP- and PS-wave inversion, anisotropy parameters were derived for use in fracture prediction. Finally, we predicted unsafe mining areas with a high probability of coal and gas outbursts. The application results were verified by excavation data from the mine tunnels. Our method contributes to fracture prediction on coal mine safety.
ABA signaling components in Phelipanche aegyptiaca
Authors: Wiseglass Gil , Pri-Tal Oded , Mosquna Assaf 
Published: April 2019

AbstractObligate root holoparasite Phelipanche aegyptiaca is an agricultural pest, which infests its hosts and feeds on the sap, subsequently damaging crop yield and quality. Its notoriously viable seed bank may serve as an ideal pest control target. The phytohormone abscisic acid (ABA) was shown to regulate P. aegyptiaca seed dormancy following strigolactones germination stimulus. Transcription analysis of signaling components revealed five ABA receptors and two co-receptors (PP2C). Transcription of lower ABA-affinity subfamily III receptors was absent in all tested stages of P. aegyptiaca development and parasitism stages. P. aegyptiaca ABA receptors interacted with the PP2Cs, and inhibited their activity in an ABA-dependent manner. Moreover, sequence analysis revealed multiple alleles in two P. aegyptiaca ABA receptors, with many non-synonymous mutations. Functional analysis of selected receptor alleles identified a variant with substantially decreased inhibitory effect of PP2Cs activity in-vitro. These results provide evidence that P. aegyptiaca is capable of biochemically perceiving ABA. In light of the possible involvement of ABA in parasitic activities, the discovery of active ABA receptors and PP2Cs could provide a new biochemical target for the agricultural management of P. aegyptiaca. Furthermore, the potential genetic loss of subfamily III receptors in this species, could position P. aegyptiaca as a valuable model in the ABA perception research field.
Massive corals maintain a positive carbonate budget of a Maldivian upper reef platform despite major bleaching event
Authors: Ryan E. J. , Hanmer K. , Kench P. S. 
Published: April 2019

AbstractCoral reefs experienced the third global bleaching event in 2015–2016 due to high sea-surface temperature (SST) anomalies. Declines in net carbonate production associated with coral bleaching are implicated in reef structural collapse and cascading impacts for adjacent coral reef islands. We present the first carbonate budget study of a reef platform surface (reef crest and reef flat) in the southern Maldives and the first record of upper reef flat condition in the central Indian Ocean post the 2015–2016 coral bleaching event. Scleractinian corals were the primary carbonate producers, with live coral cover averaging between 11.1 ± 6.5 and 31.2 ± 21.8% and dominated by massive corals. Gross carbonate production rates averaged 5.9 ± 2.5 G (kg CaCO3 m2 yr−1). Bioerosion was estimated at 3.4 ± 0.4 G, resulting in an average net carbonate production rate of 2.5 ± 2.4 G. Comparison of results with a study of the fore-reef slope highlights major differences in post-bleaching carbonate budget state between the fore-reef slope and the reef platform surface. The positive reef flat carbonate budget is attributed to the persistence of massive corals (Porites spp. and Heliopora spp.) through the bleaching event.