Passive phloem loading and long-distance transport in a synthetic tree-on-a-chip

Vascular plants rely on differences of osmotic pressure to export sugars from regions of synthesis (mature leaves) to sugar sinks (roots, fruits). In this process, known as M\"unch pressure flow, the loading of sugars from photosynthetic cells to the export conduit (the phloem) is crucial, as it sets the pressure head necessary to power long-distance transport. Whereas most herbaceous plants use active mechanisms to increase phloem concentration above that of the photosynthetic cells, in most tree species, for which transport distances are largest, loading seems to occur via passive symplastic diffusion from the mesophyll to the phloem. Here, we use a synthetic microfluidic model of a passive loader to explore the nonlinear dynamics that arise during export and determine the ability of passive loading to drive long-distance transport. We first demonstrate that in our device, phloem concentration is set by the balance between the resistances to diffusive loading from the source and convective export through the phloem. Convection-limited export corresponds to classical models of M\"unch transport, where phloem concentration is close to that of the source; in contrast, diffusion-limited export leads to small phloem concentrations and weak scaling of flow rates with the hydraulic resistance. We then show that the effective regime of convection-limited export is predominant in plants with large transport resistances and low xylem pressures. Moreover, hydrostatic pressures developed in our synthetic passive loader can reach botanically relevant values as high as 10 bars. We conclude that passive loading is sufficient to drive long-distance transport in large plants, and that trees are well suited to take full advantage of passive phloem loading strategies

Hsf1 and Hsp90 orchestrate temperature-dependent global transcriptional remodelling and chromatin architecture in Candida albicans

This is the final version. Available from Nature Research via the DOI in this record.RNA-sequencing data sets are available at ArrayExpress (www.ebi.ac.uk) under accession code E-MTAB-4075. ChIP-seq data sets are available at the NCBI SRA database (http://www.ncbi.nlm.nih.gov) under accession code SRP071687. The authors declare that all other data supporting the findings of this study are available within the article and its supplementary information files, or from the corresponding author upon request.Fever is a universal response to infection, and opportunistic pathogens such as Candida albicans have evolved complex circuitry to sense and respond to heat. Here we harness RNA-seq and ChIP-seq to discover that the heat shock transcription factor, Hsf1, binds distinct motifs in nucleosome-depleted promoter regions to regulate heat shock genes and genes involved in virulence in C. albicans. Consequently, heat shock increases C. albicans host cell adhesion, damage and virulence. Hsf1 activation depends upon the molecular chaperone Hsp90 under basal and heat shock conditions, but the effects are opposite and in part controlled at the level of Hsf1 expression and DNA binding. Finally, we demonstrate that Hsp90 regulates global transcription programs by modulating nucleosome levels at promoters of stress-responsive genes. Thus, we describe a mechanism by which C. albicans responds to temperature via Hsf1 and Hsp90 to orchestrate gene expression and chromatin architecture, thereby enabling thermal adaptation and virulence.Wellcome TrustCanadian Institutes of Health ResearchCanadian Institutes of Health ResearchBiotechnology and Biological Sciences Research Council (BBSRC)European Research Council (ERC)Science and Technology Development Fund of Macau S.A.R (FDCT)Research and Development Administrative Office of the University of MacauNational Institutes of Health (NIH

Bone Mineral Density and Vascular Calcification in Children and Young Adults With CKD 4 to 5 or on Dialysis

Introduction: Older adults with chronic kidney disease (CKD) can have low bone mineral density (BMD) with concurrent vascular calcification. Mineral accrual by the growing skeleton may protect young people with CKD from extraosseous calcification. Our hypothesis was that children and young adults with increasing BMD do not develop vascular calcification. Methods: This was a multicenter longitudinal study in children and young people (5–30 years) with CKD stages 4 to 5 or on dialysis. BMD was assessed by tibial peripheral quantitative computed tomography (pQCT) and lumbar spine dual-energy X-ray absorptiometry (DXA). The following cardiovascular imaging tests were undertaken: cardiac computed tomography for coronary artery calcification (CAC), ultrasound for carotid intima media thickness z-score (cIMTz), pulse wave velocity z-score (PWVz), and carotid distensibility for arterial stiffness. All measures are presented as age-adjusted and sex-adjusted z-scores. Results: One hundred participants (median age 13.82 years) were assessed at baseline and 57 followed up after a median of 1.45 years. Trabecular BMD z-score (TrabBMDz) decreased (P = 0.01), and there was a nonsignificant decrease in cortical BMD z-score (CortBMDz) (P = 0.09). Median cIMTz and PWVz showed nonsignificant increase (P = 0.23 and P = 0.19, respectively). The annualized increase in TrabBMDz (ΔTrabBMDz) was an independent predictor of cIMTz increase (R2 = 0.48, β = 0.40, P = 0.03). Young people who demonstrated statural growth (n = 33) had lower ΔTrabBMDz and also attenuated vascular changes compared with those with static growth (n = 24). Conclusion: This hypothesis-generating study suggests that children and young adults with CKD or on dialysis may develop vascular calcification even as their BMD increases. A presumed buffering capacity of the growing skeleton may offer some protection against extraosseous calcification

Ocean temperature and salinity components of the Madden-Julian oscillation observed by Argo floats

New diagnostics of the Madden-Julian Oscillation (MJO) cycle in ocean temperature and, for the first time, salinity are presented. The MJO composites are based on 4 years of gridded Argo float data from 2003 to 2006, and extend from the surface to 1,400 m depth in the tropical Indian and Pacific Oceans. The MJO surface salinity anomalies are consistent with precipitation minus evaporation fluxes in the Indian Ocean, and with anomalous zonal advection in the Pacific. The Argo sea surface temperature and thermocline depth anomalies are consistent with previous studies using other data sets. The near-surface density changes due to salinity are comparable to, and partially offset, those due to temperature, emphasising the importance of including salinity as well as temperature changes in mixed-layer modelling of tropical intraseasonal processes. The MJO-forced equatorial Kelvin wave that propagates along the thermocline in the Pacific extends down into the deep ocean, to at least 1,400 m. Coherent, statistically significant, MJO temperature and salinity anomalies are also present in the deep Indian Ocean

Biodiversity Loss and the Taxonomic Bottleneck: Emerging Biodiversity Science

Human domination of the Earth has resulted in dramatic changes to global and local patterns of biodiversity. Biodiversity is critical to human sustainability because it drives the ecosystem services that provide the core of our life-support system. As we, the human species, are the primary factor leading to the decline in biodiversity, we need detailed information about the biodiversity and species composition of specific locations in order to understand how different species contribute to ecosystem services and how humans can sustainably conserve and manage biodiversity. Taxonomy and ecology, two fundamental sciences that generate the knowledge about biodiversity, are associated with a number of limitations that prevent them from providing the information needed to fully understand the relevance of biodiversity in its entirety for human sustainability: (1) biodiversity conservation strategies that tend to be overly focused on research and policy on a global scale with little impact on local biodiversity; (2) the small knowledge base of extant global biodiversity; (3) a lack of much-needed site-specific data on the species composition of communities in human-dominated landscapes, which hinders ecosystem management and biodiversity conservation; (4) biodiversity studies with a lack of taxonomic precision; (5) a lack of taxonomic expertise and trained taxonomists; (6) a taxonomic bottleneck in biodiversity inventory and assessment; and (7) neglect of taxonomic resources and a lack of taxonomic service infrastructure for biodiversity science. These limitations are directly related to contemporary trends in research, conservation strategies, environmental stewardship, environmental education, sustainable development, and local site-specific conservation. Today’s biological knowledge is built on the known global biodiversity, which represents barely 20% of what is currently extant (commonly accepted estimate of 10 million species) on planet Earth. Much remains unexplored and unknown, particularly in hotspots regions of Africa, South Eastern Asia, and South and Central America, including many developing or underdeveloped countries, where localized biodiversity is scarcely studied or described. ‘‘Backyard biodiversity’’, defined as local biodiversity near human habitation, refers to the natural resources and capital for ecosystem services at the grassroots level, which urgently needs to be explored, documented, and conserved as it is the backbone of sustainable economic development in these countries. Beginning with early identification and documentation of local flora and fauna, taxonomy has documented global biodiversity and natural history based on the collection of ‘‘backyard biodiversity’’ specimens worldwide. However, this branch of science suffered a continuous decline in the latter half of the twentieth century, and has now reached a point of potential demise. At present there are very few professional taxonomists and trained local parataxonomists worldwide, while the need for, and demands on, taxonomic services by conservation and resource management communities are rapidly increasing. Systematic collections, the material basis of biodiversity information, have been neglected and abandoned, particularly at institutions of higher learning. Considering the rapid increase in the human population and urbanization, human sustainability requires new conceptual and practical approaches to refocusing and energizing the study of the biodiversity that is the core of natural resources for sustainable development and biotic capital for sustaining our life-support system. In this paper we aim to document and extrapolate the essence of biodiversity, discuss the state and nature of taxonomic demise, the trends of recent biodiversity studies, and suggest reasonable approaches to a biodiversity science to facilitate the expansion of global biodiversity knowledge and to create useful data on backyard biodiversity worldwide towards human sustainability

Overdose Prevention and Naloxone Prescription for Opioid Users in San Francisco

Opiate overdose is a significant cause of mortality among injection drug users (IDUs) in the United States (US). Opiate overdose can be reversed by administering naloxone, an opiate antagonist. Among IDUs, prevalence of witnessing overdose events is high, and the provision of take-home naloxone to IDUs can be an important intervention to reduce the number of overdose fatalities. The Drug Overdose Prevention and Education (DOPE) Project was the first naloxone prescription program (NPP) established in partnership with a county health department (San Francisco Department of Public Health), and is one of the longest running NPPs in the USA. From September 2003 to December 2009, 1,942 individuals were trained and prescribed naloxone through the DOPE Project, of whom 24% returned to receive a naloxone refill, and 11% reported using naloxone during an overdose event. Of 399 overdose events where naloxone was used, participants reported that 89% were reversed. In addition, 83% of participants who reported overdose reversal attributed the reversal to their administration of naloxone, and fewer than 1% reported serious adverse effects. Findings from the DOPE Project add to a growing body of research that suggests that IDUs at high risk of witnessing overdose events are willing to be trained on overdose response strategies and use take-home naloxone during overdose events to prevent deaths

Innate Recognition of Fungal Cell Walls

The emergence of fungal infections as major causes of morbidity and mortality in immunosuppressed individuals has prompted studies into how the host recognizes fungal pathogens. Fungi are eukaryotes and as such share many similarities with mammalian cells. The most striking difference, though, is the presence of a cell wall that serves to protect the fungus from environmental stresses, particularly osmotic changes [1]. This task is made challenging because the fungus must remodel itself to allow for cell growth and division, including the conversion to different morphotypes, such as occurs during germination of spherical spores into filamentous hyphae. The cell wall also connects the fungus with its environment by triggering intracellular signaling pathways and mediating adhesion to other cells and extracellular matrices. Here, important facts and concepts critical for understanding innate sensing of the fungal cell wall by mammalian pathogens are reviewed

9/11-Related Experiences and Tasks of Landfill and Barge Workers: Qualitative Analysis from the World Trade Center Health Registry

<p>Abstract</p> <p>Background</p> <p>Few studies have documented the experiences of individuals who participated in the recovery and cleanup efforts at the World Trade Center Recovery Operation at Fresh Kills Landfill, on debris loading piers, and on transport barges after the September 11, 2001 terrorist attack.</p> <p>Methods</p> <p>Semi-structured telephone interviews were conducted with a purposive sample of workers and volunteers from the World Trade Center Health Registry. Qualitative methods were used to analyze the narratives.</p> <p>Results</p> <p>Twenty workers and volunteers were interviewed. They described the transport of debris to the Landfill via barges, the tasks and responsibilities associated with their post-9/11 work at the Landfill, and their reflections on their post-9/11 experiences. Tasks included sorting through debris, recovering human remains, searching for evidence from the terrorist attacks, and providing food and counseling services. Exposures mentioned included dust, fumes, and odors. Eight years after the World Trade Center disaster, workers expressed frustration about poor risk communication during recovery and cleanup work. Though proud of their contributions in the months after 9/11, some participants were concerned about long-term health outcomes.</p> <p>Conclusions</p> <p>This qualitative study provided unique insight into the experiences, exposures, and concerns of understudied groups of 9/11 recovery and cleanup workers. The findings are being used to inform the development of subsequent World Trade Center Health Registry exposure and health assessments.</p

Propagation of the Madden–Julian Oscillation and scale interaction with the diurnal cycle in a high-resolution GCM

The Madden–Julian Oscillation (MJO) is the chief source of tropical intra-seasonal variability, but is simulated poorly by most state-of-the-art GCMs. Common errors include a lack of eastward propagation at the correct frequency and zonal extent, and too small a ratio of eastward- to westward-propagating variability. Here it is shown that HiGEM, a high-resolution GCM, simulates a very realistic MJO with approximately the correct spatial and temporal scale. Many MJO studies in GCMs are limited to diagnostics which average over a latitude band around the equator, allowing an analysis of the MJO’s structure in time and longitude only. In this study a wider range of diagnostics is applied. It is argued that such an approach is necessary for a comprehensive analysis of a model’s MJO. The standard analysis of Wheeler and Hendon (Mon Wea Rev 132(8):1917–1932, 2004; WH04) is applied to produce composites, which show a realistic spatial structure in the MJO envelopes but for the timing of the peak precipitation in the inter-tropical convergence zone, which bifurcates the MJO signal. Further diagnostics are developed to analyse the MJO’s episodic nature and the “MJO inertia” (the tendency to remain in the same WH04 phase from one day to the next). HiGEM favours phases 2, 3, 6 and 7; has too much MJO inertia; and dies out too frequently in phase 3. Recent research has shown that a key feature of the MJO is its interaction with the diurnal cycle over the Maritime Continent. This interaction is present in HiGEM but is unrealistically weak