2,063 research outputs found

    Variability of nutrient and thermal structure in surface waters between New Zealand and Antarctica, October 2004-January 2005

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    We describe the upper ocean thermal structure and surface nutrient concentrations between New Zealand and Antarctica along five transects that cross the Subantarctic Front, the Polar Front (PF) and the southern Antarctic Circumpolar Current (ACC) front. The surface water thermal structure is coupled with variations in surface nutrient concentrations, making water masses identifiable by both temperature and nutrient ranges. In particular, a strong latitudinal gradient in orthosilicate concentration is centred at the PF. On the earlier sections that extend south-west from the Campbell Plateau, orthosilicate increases sharply southward from 10–15 to 50–55 µmol l−1 between 58° S and 60° S, while surface temperature drops from 7°C to 2°C. Nitrate increases more regularly toward the south, with concentrations ranging from 10–12 µmol l−1 at 54° S to 25–30 µmol l−1 at 66° S. The same features are observed during the later transects between New Zealand and the Ross Sea, but the sharp silica and surface temperature gradients are shifted between 60° S and 64° S. Both temporal and spatial factors may influence the observed variability. The January transect suggests an uptake of silica, orthophosphate and nitrate between 63° S and 70° S over the intervening month, with an average depletion near 37%, 44% and 29%, respectively. An N/P (nitrite + nitrate/orthophosphate) apparent drawdown ratio of 8.8±4.1 and an Si/N (silicic acid/nitrite + nitrate) apparent drawdown ratio >1 suggest this depletion results from a seasonal diatom bloom. A southward movement of the oceanic fronts between New Zealand and the Ross Sea relative to prior measurements is consistent with reports of recent warming and changes in the ACC

    COX, Harvey, Turning East : The Promise and Peril of the New Orientalism

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    Excessive soil salinity is a major ecological and agronomical problem, the adverse effects of which are becoming a serious issue in regions where saline water is used for irrigation. Plants can employ regulatory strategies, such as DNA methylation, to enable relatively rapid adaptation to new conditions. In this regard, cytosine methylation might play an integral role in the regulation of gene expression at both the transcriptional and post-transcriptional levels. Rapeseed, which is the most important oilseed crop in Europe, is classified as being tolerant of salinity, although cultivars can vary substantially in their levels of tolerance. In this study, the Methylation Sensitive Amplified Polymorphism (MSAP) approach was used to assess the extent of cytosine methylation under salinity stress in salinity-tolerant (Exagone) and salinity-sensitive (Toccata) rapeseed cultivars. Our data show that salinity affected the level of DNA methylation. In particular methylation decreased in Exagone and increased in Toccata. Nineteen DNA fragments showing polymorphisms related to differences in methylation were sequenced. In particular, two of these were highly similar to genes involved in stress responses (Lacerata and trehalose-6-phosphatase synthase S4) and were chosen to further characterization. Bisulfite sequencing and quantitative RT-PCR analysis of selected MSAP loci showed that cytosine methylation changes under salinity as well as gene expression varied. In particular, our data show that salinity stress influences the expression of the two stress-related genes. Moreover, we quantified the level of trehalose in Exagone shoots and found that it was correlated to TPS4 expression and, therefore, to DNA methylation. In conclusion, we found that salinity could induce genome-wide changes in DNA methylation status, and that these changes, when averaged across different genotypes and developmental stages, accounted for 16.8% of the total site-specific methylation differences in the rapeseed genome, as detected by MSAP analysis

    Control of silver-polymer aggregation mechanism by primary particle spatial correlations in dynamic fractal-like geometry

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    Silver nanocrystals have been prepared by reacting silver nitrate with ascorbic acid in aqueous solution containing a low concentration of a commercial polynaphtalene sulphonate polymer (Daxad 19). Various crystalline morphologies have been obtained simply by tuning the reaction temperature. We have investigated the nanoparticle formation mechanism at three different temperatures by in situ and time resolved Small Angle X ray Scattering measurements. By modeling the scattering intensity with interacting spherical particles in a fractal-like polymer-Ag matrix, we found signatures of nucleation, growth and assembly of primary particles of about 15-20 nm. We observed how the time evolution of both spatial correlations between primary particles and the dynamic fractal geometry of the polymer-Ag matrix could influence and determine both the aggregation mechanism and the morphology of forming nanostructures in solution

    Medicines dispensers' knowledge on the implementation of an artemisinin-based combination therapy policy for the treatment of uncomplicated malaria in Tanzania

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    Objectives In 2005, Tanzania changed its policy for uncomplicated malaria treatment from sulphadoxine–pyrimethamine (SP) to artemisinin-based combination therapy (ACT), specifically artemether–lumefantrine (ALU). SP remains the medicine of choice for intermittent preventive treatment in pregnancy (IPTp). There is a need to assess dispensers' knowledge regarding the treatment of uncomplicated malaria and IPTp in Tanzania given appreciable self-purchasing to improve future care. Methods Descriptive cross-sectional design with structured questionnaires to capture quantitative data, with qualitative data captured using focus groups. The study was performed at 32 private pharmacies and 33 Accredited Drug Dispensing Outlets in the Nyamagana and Sengerema Districts in Tanzania, with 20 dispensers included in the qualitative discussions. Key findings The knowledge level of dispensers in the private medicine outlets was variable. Most dispensers knew ALU was first-line treatment in uncomplicated malaria, however variable knowledge about taking ALU with fatty meals. Generally, dispensers had poor knowledge about dosing intervals for SP in IPTp and variable knowledge regarding treatments in the first trimester. Overall, 49% had good knowledge and 48% had moderate knowledge of ACT in uncomplicated malaria. There was a significant relationship between dispenser type and knowledge of ACT but no statistical relationship between the level of knowledge on IPTp and the dispenser. Conclusions The majority of dispensers in private medicines outlets have good knowledge on ACT policy in the treatment of uncomplicated malaria; however, few dispensers had good knowledge on IPTp, which may contribute to irrational dispensing of SP. This needs addressing given the extent of self-purchasing in Tanzania

    Systematic evaluation of AML-associated antigens identifies anti-U5 SNRNP200 therapeutic antibodies for the treatment of acute myeloid leukemia.

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    Despite recent advances in the treatment of acute myeloid leukemia (AML), there has been limited success in targeting surface antigens in AML, in part due to shared expression across malignant and normal cells. Here, high-density immunophenotyping of AML coupled with proteogenomics identified unique expression of a variety of antigens, including the RNA helicase U5 snRNP200, on the surface of AML cells but not on normal hematopoietic precursors and skewed Fc receptor distribution in the AML immune microenvironment. Cell membrane localization of U5 snRNP200 was linked to surface expression of the Fcγ receptor IIIA (FcγIIIA, also known as CD32A) and correlated with expression of interferon-regulated immune response genes. Anti-U5 snRNP200 antibodies engaging activating Fcγ receptors were efficacious across immunocompetent AML models and were augmented by combination with azacitidine. These data provide a roadmap of AML-associated antigens with Fc receptor distribution in AML and highlight the potential for targeting the AML cell surface using Fc-optimized therapeutics

    Dark sectors 2016 Workshop: community report

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    This report, based on the Dark Sectors workshop at SLAC in April 2016, summarizes the scientific importance of searches for dark sector dark matter and forces at masses beneath the weak-scale, the status of this broad international field, the important milestones motivating future exploration, and promising experimental opportunities to reach these milestones over the next 5-10 years

    Genetic Discrimination Between LADA and Childhood-Onset Type 1 Diabetes Within the MHC

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    OBJECTIVE The MHC region harbors the strongest loci for latent autoimmune diabetes in adults (LADA); however, the strength of association is likely attenuated compared with that for childhood-onset type 1 diabetes. In this study, we recapitulate independent effects in the MHC class I region in a population with type 1 diabetes and then determine whether such conditioning in LADA yields potential genetic discriminators between the two subtypes within this region. RESEARCH DESIGN AND METHODS Chromosome 6 was imputed using SNP2HLA, with conditional analysis performed in type 1 diabetes case subjects (n = 1,985) and control subjects (n = 2,219). The same approach was applied to a LADA cohort (n = 1,428) using population-based control subjects (n = 2,850) and in a separate replication cohort (656 type 1 diabetes case, 823 LADA case, and 3,218 control subjects). RESULTS The strongest associations in the MHC class II region (rs3957146, beta [SE] = 1.44 [0.05]), as well as the independent effect of MHC class I genes, on type 1 diabetes risk, particularly HLA-B*39 (beta [SE] = 1.36 [0.17]), were confirmed. The conditional analysis in LADA versus control subjects showed significant association in the MHC class II region (rs3957146, beta [SE] = 1.14 [0.06]); however, we did not observe significant independent effects of MHC class I alleles in LADA. CONCLUSIONS In LADA, the independent effects of MHC class I observed in type 1 diabetes were not observed after conditioning on the leading MHC class II associations, suggesting that the MHC class I association may be a genetic discriminator between LADA and childhood-onset type 1 diabetes.Peer reviewe

    Variant-specific vulnerability in metabolic connectivity and resting-state networks in behavioural variant of frontotemporal dementia.

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    Brain connectivity measures represent candidate biomarkers of neuronal dysfunction in neurodegenerative diseases. Previous findings suggest that the behavioural variant of frontotemporal dementia (bvFTD) and its variants (i.e., frontal and temporo-limbic) may be related to the vulnerability of distinct functional connectivity networks. In this study, 82 bvFTD patients were included, and two patient groups were identified as frontal and temporo-limbic bvFTD variants. Two advanced multivariate analytical approaches were applied to FDG-PET data, i.e., sparse inverse covariance estimation (SICE) method and seed-based interregional correlation analysis (IRCA). These advanced methods allowed the assessment of (i) the whole-brain metabolic connectivity, without any a priori assumption, and (ii) the main brain resting-state networks of crucial relevance for cognitive and behavioural functions. In the whole bvFTD group, we found dysfunctional connectivity patterns in frontal and limbic regions and in all major brain resting-state networks as compared to healthy controls (HC N = 82). In the two bvFTD variants, SICE and IRCA analyses identified variant-specific reconfigurations of whole-brain connectivity and resting-state networks. Specifically, the frontal bvFTD variant was characterised by metabolic connectivity alterations in orbitofrontal regions and anterior resting-state networks, while the temporo-limbic bvFTD variant was characterised by connectivity alterations in the limbic and salience networks. These results highlight different neural vulnerabilities in the two bvFTD variants, as shown by the dysfunctional connectivity patterns, with relevance for the different neuropsychological profiles. This new evidence provides further insight in the variability of bvFTD and may contribute to a more accurate classification of these patients
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