Nuclear accessibility of beta-actin mRNA is measured by 3D single-molecule real-time tracking

Imaging single proteins or RNAs allows direct visualization of the inner workings of the cell. Typically, three-dimensional (3D) images are acquired by sequentially capturing a series of 2D sections. The time required to step through the sample often impedes imaging of large numbers of rapidly moving molecules. Here we applied multifocus microscopy (MFM) to instantaneously capture 3D single-molecule real-time images in live cells, visualizing cell nuclei at 10 volumes per second. We developed image analysis techniques to analyze messenger RNA (mRNA) diffusion in the entire volume of the nucleus. Combining MFM with precise registration between fluorescently labeled mRNA, nuclear pore complexes, and chromatin, we obtained globally optimal image alignment within 80-nm precision using transformation models. We show that beta-actin mRNAs freely access the entire nucleus and fewer than 60% of mRNAs are more than 0.5 microm away from a nuclear pore, and we do so for the first time accounting for spatial inhomogeneity of nuclear organization

Crowdsourcing hypothesis tests: Making transparent how design choices shape research results

To what extent are research results influenced by subjective decisions that scientists make as they design studies? Fifteen research teams independently designed studies to answer fiveoriginal research questions related to moral judgments, negotiations, and implicit cognition. Participants from two separate large samples (total N > 15,000) were then randomly assigned to complete one version of each study. Effect sizes varied dramatically across different sets of materials designed to test the same hypothesis: materials from different teams renderedstatistically significant effects in opposite directions for four out of five hypotheses, with the narrowest range in estimates being d = -0.37 to +0.26. Meta-analysis and a Bayesian perspective on the results revealed overall support for two hypotheses, and a lack of support for three hypotheses. Overall, practically none of the variability in effect sizes was attributable to the skill of the research team in designing materials, while considerable variability was attributable to the hypothesis being tested. In a forecasting survey, predictions of other scientists were significantly correlated with study results, both across and within hypotheses. Crowdsourced testing of research hypotheses helps reveal the true consistency of empirical support for a scientific claim.</div

A CONSERVATIVE REFORMER IN T'ANG CHINA: THE LIFE AND THOUGHT OF HAN YU (768-824) (BIOGRAPHY, CONFUCIANISM).

Han Yu is famous in Chinese history both for his literature and for his defense of Confucianism at a time when it was being seriously challenged by Buddhism and religious Taoism. Although his influ- ence was limited during his own lifetime, in later times Han Yu came to symbolize the conservative Confucian values that are often identi- fied with the traditional Chinese state. This study examines Han Yu's life and thought in an attempt to determine to what extent his later image as an ideal Confucian was or was not justified. A chapter on the historical background provides the context for Han Yu's biography, which is divided into five chap- ters. This is followed by a chapter discussing the intellectual back- ground of Han Yu's thought. Two further chapters discuss, first, the basis of Han Yu's conservative image, and, second, a number of his writings which illustrate the limits of his conservatism. Han Yu's ideas are related to the political and social circumstan- ces of his times, and it is found that while he is indeed a conservative and a Confucian, the extent of both his conservatism and his Confucian orthodoxy have been exaggerated

Effect of hypoxia on anti-tumor activity of the bioreductive drug AQ4N, and characterization of cancer stem-like cells from the human lung tumor line H460

Thesis (Ph.D.)--Boston University PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at [email protected]. Thank you.Tumor hypoxia is common and can contribute to drug resistance. To take advantage of hypoxia, bioreductive drugs that are activated to cytotoxic metabolites in a hypoxic tumor environment have been developed. The cytotoxicity of one such drug, AQ4N, was assessed under normoxic and hypoxic conditions across a panel of tumor cell lines. AQ4N showed significantly increased cytotoxicity under hypoxia in rat 9L gliosarcoma and H460 human non-small cell lung carcinoma cell cultures, but not in cultures often other human cancer cell lines. Thus, the bioreductive activation of AQ4N is not widespread in cancer cell lines. Protein levels of the quinone reductase DT-diaphorase were poorly correlated with AQ4N chemosensitivity across the cell line panel, and AQ4N chemosensitivity was unaffected by DT-diaphorase inhibitors, indicating little contribution of DT-diaphorase to AQ4N cytotoxicity. The vasodilator hydralazine decreased tumor perfusion and increased tumor hypoxia in 9L tumor xenografts, and to a lesser extent in H460 xenografts, but did not increase AQ4N-dependent anti-tumor activity. Combining of AQ4N with the anti-angiogenic drug axitinib did not augment AQ4N anti-tumor activity beyond that of axitinib alone, despite the increased hypoxic environment. Thus, AQ4N activation in vivo requires tumor hypoxia that is more extensive or prolonged than can readily be achieved by vasodilation or anti-angiogenic drug treatment. Cancer stem-like cells have been proposed to be critical for tumor growth, initiation, and drug resistance. Stem-like cells from six human tumor cell lines were isolated at frequencies ranging from 12-69% based on their characteristic holoclone morphology. All but one tumor cell line yielded holoclones with the capacity for self-renewal. Tumor xenografts grown from H460 holoclones showed significant increases in microvessel density and tumor blood perfusion compared to parental H460 tumors. Microarray analysis identified genes commonly dysregulated in holoclone-derived H460 tumors, including a network of genes associated with angiogenesis. These and other genes may serve as therapeutic targets to eliminate cancer stem-like cells or inhibit angiogenesis in H460 tumors. Together, these studies advance efforts to improve bioreductive drug activity through anti-angiogenesis and elucidate the role of stem-like cells in tumor angiogenesis

Marine sediment record from the East Antarctic margin reveals dynamics of ice sheet recession

The Antarctic shelf is traversed by large-scale troughs developed by glacial erosion. Swath bathymetric, lithologic, and chronologic data from jumbo piston cores from four sites along the East Antarctic margin (Iceberg Alley, the Nielsen Basin, the Svenner Channel, and the Mertz-Ninnis Trough) are used to demonstrate that these cross-shelf features controlled development of calving bay reentrants in the Antarctic ice sheet during deglaciation. At all sites except the Mertz-Ninnis Trough, the transition between the Last Glacial Maximum and the Holocene is characterized by varved couplets deposited during a short interval of extremely high primary productivity in a fjordlike setting. Nearly monospecific layers of the diatom Chaetoceros alternate with slightly more terrigenous layers containing a mixed diatom assemblage. We propose that springtime diatom blooms dominated by Chaetoceros were generated within well-stratified and restricted surface waters of calving bays that were influenced by the input of iron-rich meltwater. Intervening post-bloom summer-fall laminae were formed through the downward flux of terrigenous material sourced from melting glacial ice combined with mixed diatom assemblages. Radiocarbon-based chronologies that constrain the timing of deposition of the varved sediments within calving bay reentrants along the East Antarctic margin place deglaciation between ca. 10,500–11,500 cal yr B.P., post-dating Meltwater Pulse 1A (14,200 cal yr B.P.) and indicating that retreat of ice from the East Antarctic margin was not the major contributor to this pulse of meltwater

Cryoinjury to pig heart : Near-infrared spectroscopic (NIRS) imaging study.

NRC publication: Ye

Post-glacial seasonal diatom record of the Mertz Glacier Polynya, East Antarctica

An ultra-high-resolution post-glacial laminated sediment record from Mertz Ninnis Trough, East Antarctic Margin (EAM), has been analysed using SEM backscattered electron imagery, secondary electron imagery and quantitative diatom abundance. Laminations are classified using visually dominant diatom species and terrigenous content. Four biogenic diatom ooze laminae types, one diatom-bearing terrigenous lamina type and one diatom-bearing terrigenous sub-lamina type have been identified. Diatom ooze lamina types comprise near-monogeneric Hyalochaete Chaetoceros spp. resting spore laminae, laminae characterised by Corethron pennatum, laminae characterised by Rhizosolenia spp. and mixed diatom assemblage laminae. Diatom-bearing terrigenous lamina and sub-lamina types comprise mixed diatom assemblage terrigenous laminae and sub-laminae characterised by Porosira glacialis resting spores. Formation of each of these lamina types is controlled by seasonal changes in nutrients, oceanographic regimes and the Mertz Glacier Polynya dynamics

Universal Non-Diffusive Slow Dynamics in Aging Soft Matter

this paper, we present light scattering measurements of the ultraslow dynamics and the aging of several soft matter jammed systems. Remarkably, we find that for all systems the dynamic structure factor exhibit the same very unusual behavior: at long times an ultraslow, &quot; compressedexponential &quot; relaxation, whose characteristic time scales as the inverse scattering vector, leads to the complete loss of correlation of the scattered light. This behavior is in sharp contrast with the di#usive or sub-di#usive, slower-than-exponential relaxation typically observed when approaching the jammed phase from the fluid side. We propose a simple model to explain these uncommon dynamics, based on the relaxation of internal stresses, which are built in the sample at the jamming transition. The observation of the very same dynamics in systems ranging from tenuous colloidal fractal gels to concentrated emulsions, and from lamellar gels to micellar polycrystals suggests the generality of this behavior in disordered, jammed, soft materials, underlying the central role of stress relaxation on the system evolutio