3,205 research outputs found

    Convergent development of low-relatedness supercolonies in Myrmica ants.

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    Many ant species have independently evolved colony structures with multiple queens and very low relatedness among nestmate workers, but it has remained unclear whether low-relatedness kin structures can repeatedly arise in populations of the same species. Here we report a study of Danish island populations of the red ant Myrmica sulcinodis and show that it is likely that such repeated developments occur. Two microsatellite loci were used to estimate genetic differentiation (F(ST)) among three populations and nestmate relatedness within these populations. The F(ST) values were highly significant due to very different allele frequencies among the three populations with relatively few common alleles and relatively many rare alleles, possibly caused by single queen foundation and rare subsequent immigration. Given the isolation of the islands and the low investment in reproduction, we infer that each of the populations was most likely established by a single queen, even though all three extant populations now have within-colony relatedness 95%), and the genetic differentiation of nests showed a significantly positive correlation with the distance between them. Both male-biased sex-ratio and genetic viscosity are expected characteristics of populations where queens have very local dispersal and where new colonies are initiated through nest-budding. Based on a comparison with other M. sulcinodis populations we hypothesise a distinct succession of population types and suggest that this may be a possible pathway to unicoloniality, ie, development towards a complete lack of colony kin structure and unrelated nestmate workers

    Bronchoscopic assessment of airway retention time of aerosolized xylitol

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    BACKGROUND: Human airway surface liquid (ASL) has abundant antimicrobial peptides whose potency increases as the salt concentration decreases. Xylitol is a 5-carbon sugar that has the ability to lower ASL salt concentration, potentially enhancing innate immunity. Xylitol was detected for 8 hours in the ASL after application in airway epithelium in vitro. We tested the airway retention time of aerosolized iso-osmotic xylitol in healthy volunteers. METHODS: After a screening spirometry, volunteers received 10 ml of nebulized 5% xylitol. Bronchoscopy was done at 20 minutes (n = 6), 90 minutes (n = 6), and 3 hours (n = 5) after nebulization and ASL was collected using microsampling probes, followed by bronchoalveolar lavage (BAL). Xylitol concentration was measured by nuclear magnetic resonance spectroscopy and corrected for dilution using urea concentration. RESULTS: All subjects tolerated nebulization and bronchoscopy well. Mean ASL volume recovered from the probes was 49 ± 23 μl. The mean ASL xylitol concentration at 20, 90, and 180 minutes was 1.6 ± 1.9 μg/μl, 0.6 ± 0.6 μg/μl, and 0.1 ± 0.1 μg/μl, respectively. Corresponding BAL concentration corrected for dilution was consistently lower at all time points. The terminal half-life of aerosolized xylitol obtained by the probes was 45 minutes with a mean residence time of 65 minutes in ASL. Corresponding BAL values were 36 and 50 minutes, respectively. CONCLUSION: After a single dose nebulization, xylitol was detected in ASL for 3 hours, which was shorter than our in vitro measurement. The microsampling probe performed superior to BAL when sampling bronchial ASL

    Dams and Dynasty, and the Colonial Transformation of Balinese Irrigation Management

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    This article takes issue with Stephen Lansing’s bottom-up model of Balinese irrigation management. Based on archival research and extensive fieldwork in the former south Balinese kingdom of Mengwi, it is argued that in pre-colonial days large scale irrigation depended largely on dynastic involvement. During the colonial period (1906–1942) the Dutch took over the role of regional irrigation management while they strengthened the autonomy of local irrigation associations

    Developing and applying heterogeneous phylogenetic models with XRate

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    Modeling sequence evolution on phylogenetic trees is a useful technique in computational biology. Especially powerful are models which take account of the heterogeneous nature of sequence evolution according to the "grammar" of the encoded gene features. However, beyond a modest level of model complexity, manual coding of models becomes prohibitively labor-intensive. We demonstrate, via a set of case studies, the new built-in model-prototyping capabilities of XRate (macros and Scheme extensions). These features allow rapid implementation of phylogenetic models which would have previously been far more labor-intensive. XRate's new capabilities for lineage-specific models, ancestral sequence reconstruction, and improved annotation output are also discussed. XRate's flexible model-specification capabilities and computational efficiency make it well-suited to developing and prototyping phylogenetic grammar models. XRate is available as part of the DART software package: http://biowiki.org/DART .Comment: 34 pages, 3 figures, glossary of XRate model terminolog

    Association of creatine kinase and skin toxicity in phase I trials of anticancer agents.

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    BACKGROUND: We investigated the association between skin rash and plasma creatine kinase (CK) levels in oncology phase I trials. METHODS: We analysed data from 295 patients treated at our institution within 25 phase I trials which included CK measurements in the protocol. Trials involved drugs targeting EGFR/HER2, m-TOR, VEGFR, SRC/ABL, aurora kinase, BRAF/MEK, PARP, CDK, A5B1 integrin, as well as oncolytic viruses and vascular disrupting agents. RESULTS: Creatine kinase measurements were available for 278 patients. The highest levels of plasma CK during the trial were seen among patients with Grade (G) 2/3 rash (median 249 U l(-1)) compared with G1 (median 81 U l(-1)) and no rash (median 55 U l(-1)) (P<0.001). There was a significant reduction in CK after the rash resolved (mean 264.2 vs 100.1; P=0.012) in 25 patients, where serial CK values were available. In vitro exposure of human keratinocytes to EGFR, MEK and a PI3Kinase/m-TOR inhibitor led to the increased expression of CK-brain and not CK-muscle or mitochondrial-CK. CONCLUSION: Plasma CK elevation is associated with development of skin rash caused by novel anticancer agents. This should be studied further to characterise different isoforms as this will change the way we report adverse events in oncology phase I clinical trials

    The optical afterglow of the short gamma-ray burst GRB 050709

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    It has long been known that there are two classes of gamma-ray bursts (GRBs), mainly distinguished by their durations. The breakthrough in our understanding of long-duration GRBs (those lasting more than ~2 s), which ultimately linked them with energetic Type Ic supernovae, came from the discovery of their long-lived X-ray and optical afterglows, when precise and rapid localizations of the sources could finally be obtained. X-ray localizations have recently become available for short (duration <2 s) GRBs, which have evaded optical detection for more than 30 years. Here we report the first discovery of transient optical emission (R-band magnitude ~23) associated with a short burst; GRB 050709. The optical afterglow was localized with subarcsecond accuracy, and lies in the outskirts of a blue dwarf galaxy. The optical and X-ray afterglow properties 34 h after the GRB are reminiscent of the afterglows of long GRBs, which are attributable to synchrotron emission from ultrarelativistic ejecta. We did not, however, detect a supernova, as found in most nearby long GRB afterglows, which suggests a different origin for the short GRBs.Comment: 11 pages, 3 figures, press material at http://www.astro.ku.dk/dark

    Female economic dependence and the morality of promiscuity

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    This article is made available through the Brunel Open Access Publishing Fund. Copyright @ The Author(s) 2014.In environments in which female economic dependence on a male mate is higher, male parental investment is more essential. In such environments, therefore, both sexes should value paternity certainty more and thus object more to promiscuity (because promiscuity undermines paternity certainty). We tested this theory of anti-promiscuity morality in two studies (N = 656 and N = 4,626) using U.S. samples. In both, we examined whether opposition to promiscuity was higher among people who perceived greater female economic dependence in their social network. In Study 2, we also tested whether economic indicators of female economic dependence (e.g., female income, welfare availability) predicted anti-promiscuity morality at the state level. Results from both studies supported the proposed theory. At the individual level, perceived female economic dependence explained significant variance in anti-promiscuity morality, even after controlling for variance explained by age, sex, religiosity, political conservatism, and the anti-promiscuity views of geographical neighbors. At the state level, median female income was strongly negatively related to anti-promiscuity morality and this relationship was fully mediated by perceived female economic dependence. These results were consistent with the view that anti-promiscuity beliefs may function to promote paternity certainty in circumstances where male parental investment is particularly important

    Evolutionary Modeling and Prediction of Non-Coding RNAs in Drosophila

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    We performed benchmarks of phylogenetic grammar-based ncRNA gene prediction, experimenting with eight different models of structural evolution and two different programs for genome alignment. We evaluated our models using alignments of twelve Drosophila genomes. We find that ncRNA prediction performance can vary greatly between different gene predictors and subfamilies of ncRNA gene. Our estimates for false positive rates are based on simulations which preserve local islands of conservation; using these simulations, we predict a higher rate of false positives than previous computational ncRNA screens have reported. Using one of the tested prediction grammars, we provide an updated set of ncRNA predictions for D. melanogaster and compare them to previously-published predictions and experimental data. Many of our predictions show correlations with protein-coding genes. We found significant depletion of intergenic predictions near the 3′ end of coding regions and furthermore depletion of predictions in the first intron of protein-coding genes. Some of our predictions are colocated with larger putative unannotated genes: for example, 17 of our predictions showing homology to the RFAM family snoR28 appear in a tandem array on the X chromosome; the 4.5 Kbp spanned by the predicted tandem array is contained within a FlyBase-annotated cDNA
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