bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microchondrules in two unequilibrated ordinary chondrites: Evidence for formation by splattering from chondrules during stochastic collisions in the solar nebula
Authors: Dobrică E. , Brearley A. J. 
Published: March 2016

AbstractThe diversity of silicate, glassy spherules analogous to chondrules, called microchondrules, and the implications for their presence in unequilibrated ordinary chondrites (UOCs) were investigated using different electron microscope techniques. Our observations show that the abundance of microchondrules in UOCs is much larger than the values proposed by previous studies. We identified two different types of microchondrules, porous and nonporous, embedded within fine‐grained matrices and type I chondrule rims. The porous microchondrules are characterized by distinctive textures and chemical compositions that have not been recognized previously. Additionally, we show detailed textures and chemical compositions of protuberances of silicate materials, connected to the chondrules and ending with microchondrules. We suggest that microchondrules and protuberances formed from materials splattered from the chondrules during stochastic collisions when they were still either completely or partially molten. The occurrence and distinct morphologies of microchondrules and protuberances suggest that rather than just a passive flash melting of chondrules, an additional event perturbed the molten chondrules before they underwent cooling. The bulk chemical compositions suggest that (1) nonporous microchondrules and protuberances were formed by splattering of materials that are compositionally similar to the bulk silicate composition of type I chondrules, and (2) the porous microchondrules could represent the splattered melt products of a less evolved, fine‐grained dust composition. The preservation of protuberances and microchondrules in the rims suggests that the cooling and accretion rates were exceptionally fast and that they represent the last objects that were formed before the accretion of the parent bodies of OCs.
Adaptive divergence despite strong genetic drift: genomic analysis of the evolutionary mechanisms causing genetic differentiation in the island fox (Urocyon littoralis)
Authors: Funk W. Chris , Lovich Robert E. , Hohenlohe Paul A. , Hofman Courtney A. , Morrison Scott A. , Sillett T. Scott , Ghalambor Cameron K. , Maldonado Jesus E. , Rick Torben C. , Day Mitch D. , Polato Nicholas R. , Fitzpatrick Sarah W. , Coonan Timothy J. , Crooks Kevin R. , Dillon Adam , Garcelon David K. , King Julie L. , Boser Christina L. , Gould Nicholas , Andelt William F. 
Published: March 2016

AbstractThe evolutionary mechanisms generating the tremendous biodiversity of islands have long fascinated evolutionary biologists. Genetic drift and divergent selection are predicted to be strong on islands and both could drive population divergence and speciation. Alternatively, strong genetic drift may preclude adaptation. We conducted a genomic analysis to test the roles of genetic drift and divergent selection in causing genetic differentiation among populations of the island fox (Urocyon littoralis). This species consists of six subspecies, each of which occupies a different California Channel Island. Analysis of 5293 SNP loci generated using Restriction‐site Associated DNA (RAD) sequencing found support for genetic drift as the dominant evolutionary mechanism driving population divergence among island fox populations. In particular, populations had exceptionally low genetic variation, small Ne (range = 2.1–89.7; median = 19.4), and significant genetic signatures of bottlenecks. Moreover, islands with the lowest genetic variation (and, by inference, the strongest historical genetic drift) were most genetically differentiated from mainland grey foxes, and vice versa, indicating genetic drift drives genome‐wide divergence. Nonetheless, outlier tests identified 3.6–6.6% of loci as high FST outliers, suggesting that despite strong genetic drift, divergent selection contributes to population divergence. Patterns of similarity among populations based on high FST outliers mirrored patterns based on morphology, providing additional evidence that outliers reflect adaptive divergence. Extremely low genetic variation and small Ne in some island fox populations, particularly on San Nicolas Island, suggest that they may be vulnerable to fixation of deleterious alleles, decreased fitness and reduced adaptive potential.
Contemporary genetic structure and postglacial demographic history of the black scorpionfish, Scorpaena porcus, in the Mediterranean and the Black Seas
Authors: Boissin E. , Micu D. , Janczyszyn‐Le Goff M. , Neglia V. , Bat L. , Todorova V. , Panayotova M. , Kruschel C. , Macic V. , Milchakova N. , Keskin Ç. , Anastasopoulou A. , Nasto I. , Zane L. , Planes S. 
Published: March 2016

AbstractUnderstanding the distribution of genetic diversity in the light of past demographic events linked with climatic shifts will help to forecast evolutionary trajectories of ecosystems within the current context of climate change. In this study, mitochondrial sequences and microsatellite loci were analysed using traditional population genetic approaches together with Bayesian dating and the more recent approximate Bayesian computation scenario testing. The genetic structure and demographic history of a commercial fish, the black scorpionfish, Scorpaena porcus, was investigated throughout the Mediterranean and Black Seas. The results suggest that the species recently underwent population expansions, in both seas, likely concomitant with the warming period following the Last Glacial Maximum, 20 000 years ago. A weak contemporaneous genetic differentiation was identified between the Black Sea and the Mediterranean Sea. However, the genetic diversity was similar for populations of the two seas, suggesting a high number of colonizers entered the Black Sea during the interglacial period and/or the presence of a refugial population in the Black Sea during the glacial period. Finally, within seas, an east/west genetic differentiation in the Adriatic seems to prevail, whereas the Black Sea does not show any structured spatial genetic pattern of its population. Overall, these results suggest that the Black Sea is not that isolated from the Mediterranean, and both seas revealed similar evolutionary patterns related to climate change and changes in sea level.
Demographic history of speciation in a Senecio altitudinal hybrid zone on Mt. Etna
Authors: Filatov Dmitry A. , Osborne Owen G. , Papadopulos Alexander S. T. 
Published: March 2016

AbstractHybrid zones typically form as a result of species coming into secondary contact, but can also be established in situ as an ecotonal hybrid zone, a situation which has been reported far less frequently. An altitudinal hybrid zone on Mount Etna between two ragwort species (the low elevation Senecio chrysanthemifolius and high elevation S. aethnensis) could potentially represent either of these possibilities. However, a scenario of secondary contact vs. speciation with gene flow has not been explicitly tested. Here, we test these alternatives and demonstrate that the data do not support secondary contact. Furthermore, we report that the previous analyses of speciation history of these species were based on admixed populations, which has led to inflated estimates of ongoing, interspecific gene flow. Our new analyses, based on ‘pure’ S. aethnensis and S. chrysanthemifolius populations, reveal gene exchange of less than one effective migrant per generation, a level low enough to allow the species to accumulate neutral, genomewide differences. Overall, our results are consistent with a scenario of speciation with gene flow and a divergence time which coincides with the rise of Mt. Etna to altitudes above 2000 m (~150 KY). Further work to quantify the role of adaptation to contrasting environments of high and low altitudes will be needed to support the scenario of recent ecological speciation in this system.
Synergistic interaction of glyceraldehydes‐3‐phosphate dehydrogenase and ArsJ, a novel organoarsenical efflux permease, confers arsenate resistance
Authors: Chen Jian , Yoshinaga Masafumi , Garbinski Luis D. , Rosen Barry P. 
Published: March 2016

SummaryMicrobial biotransformations are major contributors to the arsenic biogeocycle. In parallel with transformations of inorganic arsenic, organoarsenicals pathways have recently been recognized as important components of global cycling of arsenic. The well‐characterized pathway of resistance to arsenate is reduction coupled to arsenite efflux. Here, we describe a new pathway of arsenate resistance involving biosynthesis and extrusion of an unusual pentavalent organoarsenical. A number of arsenic resistance (ars) operons have two genes of unknown function that are linked in these operons. One, gapdh, encodes the glycolytic enzyme glyceraldehyde‐3‐phosphate dehydrogenase. The other, arsJ, encodes a major facilitator superfamily (MFS) protein. The two genes were cloned from the chromosome of Pseudomonas aeruginosa. When expressed together, but not alone, in Escherichia coli, gapdh and arsJ specifically conferred resistance to arsenate and decreased accumulation of As(V). Everted membrane vesicles from cells expressing arsJ accumulated As(V) in the presence of purified GAPDH, D‐glceraldehylde 3‐phosphate (G3P) and NAD+. GAPDH forms the unstable organoarsenical 1‐arseno‐3‐phosphoglycerate (1As3PGA). We propose that ArsJ is an efflux permease that extrudes 1As3PGA from cells, where it rapidly dissociates into As(V) and 3‐phosphoglycerate (3PGA), creating a novel pathway of arsenate resistance.
Joining forces: first application of a rapamycin‐induced dimerizable Cre system for conditional null mutant analysis in Leishmania
Authors: Späth Gerald F. , Clos Joachim 
Published: March 2016

SummaryReverse genetics in Leishmania spp has gained importance beyond basic research as efforts increase to discover and validate new drug targets. Often, the most promising targets are essential for viability of the parasites, defying a genetic analysis by current gene replacement strategies. Duncan et al. demonstrate the applicability of DiCre recombination in Leishmania for induced replacement of the kinase CRK3 gene in promastigotes. DiCre gene replacement leads to the rapid loss of the gene and allows monitoring the phenotypic effects of the loss of function, eliminating the need for prolonged cultivation and selection. Implementation of the DiCre approach will allow functional genetics of the most important of Leishmania genes and is likely to boost genetic research and drug target discovery.
Recent mating‐system evolution in Eichhornia is accompanied by cis‐regulatory divergence
Authors: Arunkumar Ramesh , Maddison Teresa I. , Barrett Spencer C. H. , Wright Stephen I. 
Published: March 2016

Summary

The evolution of predominant self‐fertilization from cross‐fertilization in plants is accompanied by diverse changes to morphology, ecology and genetics, some of which likely result from regulatory changes in gene expression. We examined changes in gene expression during early stages in the transition to selfing in populations of animal‐pollinated Eichhornia paniculata with contrasting mating patterns.

We crossed plants from outcrossing and selfing populations and tested for the presence of allele‐specific expression (ASE) in floral buds and leaf tissue of F1 offspring, indicative of cis‐regulatory changes.

We identified 1365 genes exhibiting ASE in floral buds and leaf tissue. These genes preferentially expressed alleles from outcrossing parents. Moreover, we found evidence that genes exhibiting ASE had a greater nonsynonymous diversity compared to synonymous diversity in the selfing parents.

Our results suggest that the transition from outcrossing to high rates of self‐fertilization may have the potential to shape the cis‐regulatory genomic landscape of angiosperm species, but that the changes in ASE may be moderate, particularly during the early stages of this transition.
The endophytic symbiont Epichloë festucae establishes an epiphyllous net on the surface of Lolium perenne leaves by development of an expressorium, an appressorium‐like leaf exit structure
Authors: Becker Matthias , Becker Yvonne , Green Kimberly , Scott Barry 
Published: March 2016

Summary

Epichloë festucae forms a mutualistic symbiotic association with Lolium perenne. This biotrophic fungus systemically colonizes the intercellular spaces of aerial tissues to form an endophytic hyphal network. E. festucae also grows as an epiphyte, but the mechanism for leaf surface colonization is not known. Here we identify an appressorium‐like structure, which we call an expressorium that allows endophytic hyphae to penetrate the cuticle from the inside of the leaf to establish an epiphytic hyphal net on the surface of the leaf.

We used a combination of scanning electron, transmission electron and confocal laser scanning microscopy to characterize this novel fungal structure and determine the composition of the hyphal cell wall using aniline blue and wheat germ agglutinin labelled with Alexafluor‐488.

Expressoria differentiate immediately below the cuticle in the leaf blade and leaf sheath intercalary cell division zones where the hyphae grow by tip growth. Differentiation of this structure requires components of both the NoxA and NoxB NADPH oxidase complexes. Major remodelling of the hyphal cell wall occurs following exit from the leaf.

These results establish that the symbiotic association of E. festucae with L. perenne involves an interconnected hyphal network of both endophytic and epiphytic hyphae.
Household Shocks and Education Investments in Madagascar
Authors: Glick Peter J. , Sahn David E. , Walker Thomas F. 
Published: March 2016

AbstractThis paper investigates the impact of exogenous shocks to household income, assets and labour supply on children's school attendance in Madagascar. The analysis uses a unique data set with 10 years of recall data on school attendance and household shocks. We find that the probability of a child dropping out of school increases significantly when the household experiences an illness, death or asset shock. We propose a test to distinguish whether the impact of shocks on school attendance can be attributed to credit constraints, labour market rigidities, or a combination of the two. The results suggest that credit constraints, rather than labour market rigidities, explain the inability of households in Madagascar to keep their children in school during times of economic stress.
The effect of dietary approaches to stop hypertension (DASH) diet on weight and body composition in adults: a systematic review and meta‐analysis of randomized controlled clinical trials
Authors: Soltani Sepideh , Shirani Fatemeh , Chitsazi Maryam J , Salehi‐Abargouei Amin 
Published: March 2016

SummaryBackgroundDietary approaches to stop hypertension (DASH) diet is rich in foods that are proposed to be inversely associated with obesity. Therefore, DASH might better affect body weight; however, published data are conflicting.ObjectiveTo assess the effect of DASH on body weight and composition in adults.MethodsPubMed, EMBASE, Scopus and Google scholar were searched up to December 2015, for relevant randomized controlled clinical trials. Mean changes in body weight, body mass index (BMI) and waist circumference (WC) were extracted.ResultsThirteen articles (ten for body weight, six for BMI and two for WC) were eligible. Meta‐analysis revealed that adults on DASH diet lose more weight (weighted mean difference [WMD] = −1.42 kg, 95% confidence interval [95%CI]: −2.03, −0.82) in 8–24 weeks, BMI (WMD = −0.42 kg m−2, 95%CI: −0.64, −0.20) in 8–52 weeks and WC (WMD = −1.05 cm, 95%CI: −1.61, −0.49) in 24 weeks compared with controls. Low caloric DASH led to even more weight reduction when compared with other low‐energy diets. In addition, the effect was greater in overweight/obese participants and when compared with typical (Western or population's usual) diets.ConclusionDASH diet is a good choice for weight management particularly for weight reduction in overweight and obese participants. © 2016 World Obesity
Resilience of tropical dry forests – a meta‐analysis of changes in species diversity and composition during secondary succession
Authors: Derroire Géraldine , Balvanera Patricia , Castellanos‐Castro Carolina , Decocq Guillaume , Kennard Deborah K. , Lebrija‐Trejos Edwin , Leiva Jorge A. , Odén Per‐Christer , Powers Jennifer S. , Rico‐Gray Victor , Tigabu Mulualem , Healey John R. 
Published: March 2016

Assessing the recovery of species diversity and composition after major disturbance is key to understanding the resilience of tropical forests through successional processes, and its importance for biodiversity conservation. Despite the specific abiotic environment and ecological processes of tropical dry forests, secondary succession has received less attention in this biome than others and changes in species diversity and composition have never been synthesised in a systematic and quantitative review. This study aims to assess in tropical dry forests 1) the directionality of change in species richness and evenness during secondary succession, 2) the convergence of species composition towards that of old‐growth forest and 3) the importance of the previous land use, precipitation regime and water availability in influencing the direction and rate of change. We conducted meta‐analyses of the rate of change in species richness, evenness and composition indices with succession in 13 tropical dry forest chronosequences. Species richness increased with succession, showing a gradual accumulation of species, as did Shannon evenness index. The similarity in species composition of successional forests with old‐growth forests increased with succession, yet at a low rate. Tropical dry forests therefore do show resilience of species composition but it may never reach that of old‐growth forests. We found no significant differences in rates of change between different previous land uses, precipitation regimes or water availability. Our results show high resilience of tropical dry forests in term of species richness but a slow recovery of species composition. They highlight the need for further research on secondary succession in this biome and better understanding of impacts of previous land‐use and landscape‐scale patterns.SynthesisSecondary forests account for an increasing proportion of remaining tropical forest. Assessing their resilience is key to conservation of their biodiversity. Our study is the first meta‐analysis of species changes during succession focussing on tropical dry forests, a highly threatened yet understudied biome. We show a gradual species accumulation and convergence of composition towards that of old‐growth forests. While secondary tropical dry forests offer good potential for biodiversity conservation, their capacity for recovery at a sufficient rate to match threats is uncertain. Further research on this biome is needed to understand the effect of land use history and landscape processes.
ADMINISTRATIVE POLITICIZATION OR CONTESTABILITY? HOW POLITICAL ADVISERS AFFECT NEUTRAL COMPETENCE IN POLICY PROCESSES
Authors: ÖHBERG PATRIK , MUNK CHRISTIANSEN PETER , NIKLASSON BIRGITTA 
Published: March 2016

AbstractThere is limited empirical research on the extent to which politicized recruitment of ministerial advisers affects the quality of the policy process. In this article we take a novel step by looking at two possible consequences of increased political recruitment for the policy process: administrative politicization and contestability. We deploy a Most Similar Systems comparison of Denmark and Sweden and include survey answers from 657 civil servants in managerial positions. We find that political recruitment of top civil servants, such as Swedish state secretaries, restricts the access of the civil service to the minister, but it does not substantially politicize the policy process. Danish civil servants perceive themselves as more contested by the relatively few Danish political advisers than their Swedish colleagues. Our results imply that the organization of political advice is a crucial factor for politicization and contestability
Combined Use of High Radiofrequency Disk Ablation, Annulus Modulation, and Manual Nucleotomy in a Patient with Extruded Disk Herniation
Authors: Beyaz Serbülent Gökhan , İnanmaz Mustafa Erkan , Zengin Ezgi Şen , Ülgen Ali Metin 
Published: March 2016

AbstractDifferent minimally invasive procedures are used to treat lumbar disk herniation. It is important to differentiate these techniques due to their specific effects and the disparate technical issues associated with each. This report describes a successful case involving the use of mechanical decompression in conjunction with radiofrequency ablation to treat a patient with pain and neurological deficits due to an extruded disk hernia.Case ReportA 43‐year‐old male had magnetic resonance imaging (MRI) demonstrating an extruded disk herniation in the left foraminal region, compression at the left spinal nerve root, and obliteration of the left foraminal entrance of the L5‐S1 distribution. In the operating room, sufficient disk material was removed using grasping forceps, and then, the Disc‐FX system with a Trigger‐Flex probe (Elliquence, Baldwin, NY, U.S.A.) was inserted. Modulation of the annulus was performed in bipolar hemo mode, and nucleus ablation was conducted in bipolar turbo mode within a 1.7‐MHz frequency range. Among the available minimally invasive techniques, newly developed technologies may become important treatment options if they enable faster rehabilitation, lower rates of recurrence, shorter hospital stays, and reduced medical costs.
Resolution of Intrathecal Hydromorphone or Morphine‐induced Peripheral Edema by Opioid Rotation to Fentanyl: A Case Series
Authors: Veizi Elias , Tornero‐Bold Melissa , Hayek Salim M. 
Published: March 2016

AbstractIntroductionIntrathecal therapy [IT] has become an important modality for treatment of intractable cancer and noncancer pain although adverse events limit its effectiveness.ObjectiveThe purpose of this case series was to report and discuss the lower limb edema from IT hydromorphone and morphine therapy and its resolution or nonrecurrence upon rotating the IT solution to fentanyl.MethodsCase series.ResultsFive patients, 4 women and 1 man, 55 to 67 years old implanted with IT delivery device systems [IDDS] were treated with continuous infusion of hydromorphone [4 subjects] at 95 ± 40 mcg/24 hours and morphine [1 subject] at 0.67 mg/24 hours. They developed peripheral edema of the lower extremities at an average of 4.2 months [mean, range 1 to 8 months] after implant. In 4 subjects, peripheral edema resolved by changing the IT agent to fentanyl. The mean time for complete resolution of edema was 50 ± 20 days while patients were treated with continuous infusion of fentanyl. It should be noted that all patients were receiving bupivacaine in addition to the IT opioid. In one subject, infusion of IT saline resulted in faster resolution of peripheral edema.ConclusionPeripheral lower extremity edema may occur in patients treated with IT infusion of hydromorphone or morphine, even at low doses. This report presents, to the best of our knowledge, the first case series describing the benefit of IT opioid rotation to fentanyl in alleviating challenging lower extremity edema from IT hydromorphone and morphine.