2,947 research outputs found

    Genetic differentiation, reproductive mode, and gene flow in the brooding coral Pocillopora damicornis along the Great Barrier Reef, Australia

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    The widespread and morphologically variable coral Pocillopora damicornis has been reported to exhibit huge variation in Life-history traits (e.g. mode of reproduction, growth rate, longevity and dispersal) both locally and regionally throughout the Indo-Pacific Ocean. Dispersal may be achieved by the settlement of sexually or asexually generated brooded planula larvae, by broadcast spawning or more locally through asexual fragmentation of large colonies. In the present study, we conducted a hierarchical survey of allozyme variation within:hin and among reef-crest sites on 3 mid-shelf reefs separated by up to 1200 km on the Great Barrier Reef (GBR), Australia. Our objective was to use allozyme data (1) to quantify local and regional patterns of variation in P., damicornis (along the northeastern coast of Australia), (2) to determine the relative contribution of sexual versus asexual production of planulae in P., damicornis, and (3) to estimate levels of gene flow among adjacent sites (>5 km apart) and among reefs separated by 500 to 1200 km. High levels of genotypic diversity in our samples of P. damicornis imply that dispersive propagules in this species are produced sexually rather than asexually along the length of the GBR. Corals at all sites displayed: the same level of multi-locus genotypic diversity expected for randomly mating, sexually derived populations, and the majority of individual colonies possessed unique 7-locus genotypes. We also detected consistent deficits of heterozygotes within each collection (from 3 local sites on each of the 3 widely spaced reefs). This pattern is consistent with the predicted effects of sexual reproduction associated with some localised dispersal of gametes or larvae (although other explanations cannot be excluded). Furthermore, each reef was genetically subdivided, suggesting that larval recruitment was localised and that these populations are slightly inbred: hierarchical analysis of the standardised genetic variances (F-ST) (estimated as Weir & Cockerham's theta) revealed that, although there was only moderate variation among all 9 sites (F-ST = 0.055 +/- 0.029), more variation was found among sites within reefs (F-SL = 0.035 +/- 0.04 to 0.088 +/-: 0.033) than among distant reefs (F-LT = 0.008 +/- 0.014). This homogeneity of gene frequencies across widely separated reefs implies that reefs are connected by high:gh levels of gene flow (N(e)m approximate to 31) and that local populations of P. damicornis separated by >1000 km can interbreed sufficiently to maintain a consistent suite of life-history characters

    Conceptualising connections: energy demand, infrastructures and social practices

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    Problems of climate change present new challenges for social theory. In this paper we focus on the task of understanding and analysing car dependence, using this as a case through which to introduce and explore what we take to be central but underdeveloped questions about how infrastructures and complexes of social practice connect across space and time. In taking this approach we work with the proposition that forms of energy consumption, including those associated with automobility, are usefully understood as outcomes of interconnected patterns of social practices, including working, shopping, visiting friends and family, going to school and so forth. We also acknowledge that social practices are partly constituted by, and always embedded in material arrangements. Linking these two features together we suggest that forms of car-dependence emerge through the intersection of infrastructural arrangements that are integral to the conduct of many practices at once. We consequently explore the significance of professional – and not only ‘ordinary’ – practices, especially those of planners and designers who are involved in reconfiguring infrastructures of different scales, and in the practice dynamics that follow

    Spatially Resolved Magnetic Field Structure in the Disk of a T Tauri Star

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    Magnetic fields in accretion disks play a dominant role during the star formation process but have hitherto been observationally poorly constrained. Field strengths have been inferred on T Tauri stars themselves and possibly in the innermost part of the accretion disk, but the strength and morphology of the field in the bulk of the disk have not been observed. Unresolved measurements of polarized emission (arising from elongated dust grains aligned perpendicular to the field) imply average fields aligned with the disks. Theoretically, the fields are expected to be largely toroidal, poloidal, or a mixture of the two, which imply different mechanisms for transporting angular momentum in the disks of actively accreting young stars such as HL Tau. Here we report resolved measurements of the polarized 1.25 mm continuum emission from HL Tau's disk. The magnetic field on a scale of 80 AU is coincident with the major axis (~210 AU diameter) of the disk. From this we conclude that the magnetic field inside the disk at this scale cannot be dominated by a vertical component, though a purely toroidal field does not fit the data well either. The unexpected morphology suggests that the magnetic field's role for the accretion of a T Tauri star is more complex than the current theoretical understanding.Comment: Accepted for publication in Natur

    Management of imatinib-resistant CML patients

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    Imatinib has had marked impact on outcomes in chronic myelogenous leukemia (CML) patients for all stages of the disease and is endorsed by international treatment guidelines as the first line option. Although imatinib is highly effective and well tolerated, the development of resistance represents a clinical challenge. Since the most frequently identified mechanism of acquired imatinib resistance is bcr-abl kinase domain point mutations, periodic hematologic, cytogenetic, and molecular monitoring is critical throughout imatinib therapy. Once cytogenetic remission is achieved, residual disease can be monitored by bcr-abl transcript levels as assayed by reverse transcription polymerase chain reaction (RT-PCR). Detection of bcr-abl mutants prior to and during imatinib therapy can aid in risk stratification as well as in determining therapeutic strategies. Thus, mutation screening is indicated in patients lacking or losing hematologic response. Moreover, search for mutations should also be performed when a 3-log reduction of bcr-abl transcripts is not achieved or there is a reproducible increase of transcript levels. In patients harboring mutations which confer imatinib resistance, novel second line tyrosine kinase inhibitors have demonstrated encouraging efficacy with low toxicity. Only the T315I bcr-abl mutant has proved totally resistant to all clinically available bcr-abl inhibitors. Strategies to further increase the rates of complete molecular remissions represent the next frontier in the targeted therapy of CML patients

    Climate warming, marine protected areas and the ocean-scale integrity of coral reef ecosystems

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    Coral reefs have emerged as one of the ecosystems most vulnerable to climate variation and change. While the contribution of a warming climate to the loss of live coral cover has been well documented across large spatial and temporal scales, the associated effects on fish have not. Here, we respond to recent and repeated calls to assess the importance of local management in conserving coral reefs in the context of global climate change. Such information is important, as coral reef fish assemblages are the most species dense vertebrate communities on earth, contributing critical ecosystem functions and providing crucial ecosystem services to human societies in tropical countries. Our assessment of the impacts of the 1998 mass bleaching event on coral cover, reef structural complexity, and reef associated fishes spans 7 countries, 66 sites and 26 degrees of latitude in the Indian Ocean. Using Bayesian meta-analysis we show that changes in the size structure, diversity and trophic composition of the reef fish community have followed coral declines. Although the ocean scale integrity of these coral reef ecosystems has been lost, it is positive to see the effects are spatially variable at multiple scales, with impacts and vulnerability affected by geography but not management regime. Existing no-take marine protected areas still support high biomass of fish, however they had no positive affect on the ecosystem response to large-scale disturbance. This suggests a need for future conservation and management efforts to identify and protect regional refugia, which should be integrated into existing management frameworks and combined with policies to improve system-wide resilience to climate variation and change

    Save reefs to rescue all ecosystems

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    This is the author accepted manuscript. The final version is available from Nature Research via the DOI in this recor

    Global trends in paediatric robot-assisted urological surgery: a bibliometric and Progressive Scholarly Acceptance analysis

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    The inaugural robot-assisted urological procedure in a child was performed in 2002. This study aims to catalogue the impact of this technology by utilizing bibliographic data as a surrogate measure for global diffusion activity and to appraise the quality of evidence in this field. A systematic literature search was performed to retrieve all reported cases of paediatric robot-assisted urological surgery published between 2003 and 2016. The status of scientific community acceptance was determined using a newly developed analysis model named progressive scholarly acceptance. A total of 151 publications were identified that reported 3688 procedures in 3372 patients. The most reported procedures were pyeloplasty (n = 1923) and ureteral reimplantation (n = 1120). There were 16 countries and 48 institutions represented in the literature. On average, the total case volume reported in the literature more than doubled each year (mean value increase 236.6% per annum). The level of evidence for original studies remains limited to case reports, case series and retrospective comparative studies. Progressive Scholarly Acceptance charts indicate that robot-assisted techniques for pyeloplasty or ureteral reimplantation are yet to be accepted by the scientific community. Global adoption trends for robotic surgery in paediatric urology have been progressive but remain low volume. Pyeloplasty and ureteral reimplantation are dominant applications. Robot-assisted techniques for these procedures are not supported by high quality evidence at present. Next-generation robots are forecast to be smaller, cheaper, more advanced and customized for paediatric patients. Ongoing critical evaluation must occur simultaneously with expected technology evolution

    Chronic Lymphocytic Leukemia: Insights from Lymph Nodes & Bone Marrow and Clinical Perspectives

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    B-cell chronic lymphocytic leukemia (B-CLL) is characterized by highly variable distribution of tumor mass between peripheral blood, bone marrow and lymphoid organs which is important for staging, classification and prognosis. These clinical findings with novel data about importance of B-cell receptor and its stimulation with the support of microenvironment indicate important role of tissues (lymphoid organs and bone marrow) in the pathogenesis of B-CLL. Here is presented the novel approach of simultaneous characterization of B-CLL cells form peripheral blood, bone marrow and lymph nodes by flow cytometry and immunocytochemistry, defining inter- and intraclonal diversity with respect to various molecules. These include adhesion molecules (integrins, immunoglobulins, selectins), chemokine receptors (including CXCR-4), signaling molecules and prognostic factors (CD38 and ZAP-70), proliferation and apoptosis markers (including Ki67, AgNORs with PK index, survivin, bcl-2) and therapeutic targets (CD20 and CD52) and residual hematopoietic stem cells. A number of interesting significant interactions have been discovered, pointing to the important role of neoplastic cell microenvironment. These may in addition to insights in pathogenesis and roles of different microenvironments add to diagnosis, prognosis and treatment of B-CLL patients
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