129 research outputs found
Interactive effects of elevated temperature and CO2 on two phylogeographically distinct clones of common reed (Phragmites australis)
The aboveground growth, physiological and biochemical parameters of two clones of the cosmopolitan wetland grass Phragmites australis, grown at four treatment combinations of temperature and O2, were investigated to elucidate whether their climate response differed due to inherent differences in their ecological adaptation. The two phylogeographically distinct P. australis clones (DK clone, European genetic background; ALG clone, Mediterranean genetic background) were grown for 151 days in phytotrons at 19/12 8C (day/night temperature) and 390 ppm CO2, and at elevated temperature (+5 8C) and CO2 (700 ppm) with treatment factors alone or in combination.
The ALG clone had 2–4 times higher aboveground biomass, higher light-saturated rates of photosynthesis (Pmax), maximum electron transport rates (ETRmax) and Rubisco activity, and higher photosynthetic nitrogen-use efficiency than the DK clone. The DK clone, however, produced more shoots, leaves and sideshoots, and had 9–51 % higher specific leaf area and 15–39 % higher leaf nitrogen concentration than the ALG clone. Although elevated atmospheric CO2 alone barely affected the aboveground growth of the two P. australis clones, simultaneously elevated temperature and CO2 stimulated growth and aboveground biomass. Overall, elevated CO2 stimulated photosynthesis, but the clones responded differently to a concomitant increase in CO2 and temperature, depending on the phylogeographic background of the plant. The DK clone showed overall stronger responses, and can be considered the more plastic of the two clones with respect to CO2 and
temperature. Thus, the DK clone may be better adapted to climate change than the ALG clone, at least in the short term
Causes and consequences of tipping points in river delta social-ecological systems
The sustainability of social-ecological systems within river deltas globally is in question as rapid development and environmental change trigger "negative” or “positive” tipping points depending on actors’ perspectives, e.g., regime shift from abundant sediment deposition to sediment shortage, agricultural sustainability to agricultural collapse or shift from rural to urban land. Using a systematic review of the literature, we show how cascading effects across anthropogenic, ecological, and geophysical processes have triggered numerous tipping points in the governance, hydrological and land use management of the world’s river deltas. Crossing tipping points had both positive and negative effects that generally enhanced economic development to the detriment of the environment. Assessment of deltas that featured prominently in the review revealed how outcomes of tipping points can inform the long-term trajectory of deltas towards sustainability or collapse. Management of key drivers at the delta scale can trigger positive tipping points to place social-ecological systems on a pathway towards sustainable development
Folate status of gut microbiome affects Caenorhabditis eleganslifespan
In a paper in BMC Biology Virk et al. show that Caenorhabditis elegans lifespan is extended in response to a diet of folate-deficient Escherichia coli. The deficiencies in folate biosynthesis were due to an aroD mutation, or treatment of E. coli with sulfa drugs, which are mimics of the folate precursor para-aminobenzoic acid. This study suggests that pharmacological manipulation of the gut microbiome folate status may be a viable approach to slow animal aging, and raises questions about folate supplementation. See research article http://www.http://www.biomedcentral.com/1741-7007/10/6
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Blood Pressure Lowering and Risk of Mortality in Chronic Kidney Disease: A Meta2 Analysis of Randomized Controlled Trials
Importance: Trials in hypertensive patients demonstrate that intensive blood pressure (BP) lowering reduces risk of cardiovascular disease (CVD) and all-cause mortality, but may increase risk of chronic kidney disease (CKD) incidence and progression. Whether intensive BP lowering is associated with a mortality benefit in patients with prevalent CKD remains unknown.
Objective: We conducted a meta-analysis of Randomized controlled trials (RCTs) to determine if more intensive, compared with a less intensive, BP control is associated with reduced mortality risk in persons with CKD stages 3-5.
Data Sources: Ovid Medline, Cochrane Library, Embase, Pubmed, Science Citation Index, Google Scholar, and ClinicalTrials.gov electronic databases.
Study Selection: All RCTs that compared two defined BP targets (either active treatment vs.placebo or no treatment, or intensive vs. less intensive BP control) and enrolled adult (≥18years) persons with CKD stages 3-5 (estimated glomerular filtration rate (eGFR) <60
mL/min/1.73m2) exclusively or that included a CKD subgroup between January 1950 and June 2016 were included.
Data extraction and synthesis: Two reviewers independently evaluated study quality and extracted characteristics and mortality events among persons with CKD within the intervention phase for each trial. When outcomes within the CKD group had not previously been published, we contacted trial investigators and requested data within the CKD subset of their original trials.
Main outcomes and measures: All-cause mortality during the active treatment phase of each trial.
Results: We identified 30 RCTs that potentially met inclusion criteria, among which we were able to extract the CKD subset mortality data in 18 trials. Among these, there were 1293 deaths among 15,924 participants with CKD. The mean baseline systolic blood pressure (SBP) was 148±16 mm hg in both intensive and less-intensive arms. The mean SBP dropped by 16 mm Hg to 132 mm Hg in the intensive arm and by 8 mm Hg to 140 mm Hg in the less-intensive arm. More vs. less-intensive BP control resulted in 14% lower risk of all-cause mortality (Odds Ratio (OR) 0.86; 95% CI 0.76 to 0.97, p = 0.01); a finding that was without significant heterogeneity and appeared consistent across multiple subgroups including type of treatment in the comparator arm (placebo vs. less intensive BP target), length of follow-up, presence of diabetes, CKD severity, baseline systolic blood pressure (SBP), achieved SBP during the trial and degree of SBP differences across the treatment arms.
Conclusion and Relevance: Randomization to more intensive BP control is associated with lower mortality risk among trial participants with hypertension and CKD. Further studies are required to define absolute BP targets for maximal benefit and minimal harm
Comparative Analysis of Gene Content Evolution in Phytoplasmas and Mycoplasmas
Phytoplasmas and mycoplasmas are two groups of important pathogens in the bacterial class Mollicutes. Because of their economical and clinical importance, these obligate pathogens have attracted much research attention. However, difficulties involved in the empirical study of these bacteria, particularly the fact that phytoplasmas have not yet been successfully cultivated outside of their hosts despite decades of attempts, have greatly hampered research progress. With the rapid advancements in genome sequencing, comparative genome analysis provides a new approach to facilitate our understanding of these bacteria. In this study, our main focus is to investigate the evolution of gene content in phytoplasmas, mycoplasmas, and their common ancestor. By using a phylogenetic framework for comparative analysis of 12 complete genome sequences, we characterized the putative gains and losses of genes in these obligate parasites. Our results demonstrated that the degradation of metabolic capacities in these bacteria has occurred predominantly in the common ancestor of Mollicutes, prior to the evolutionary split of phytoplasmas and mycoplasmas. Furthermore, we identified a list of genes that are acquired by the common ancestor of phytoplasmas and are conserved across all strains with complete genome sequences available. These genes include several putative effectors for the interactions with hosts and may be good candidates for future functional characterization
Integrative Genome Comparison of Primary and Metastatic Melanomas
A cardinal feature of malignant melanoma is its metastatic propensity. An incomplete view of the genetic events driving metastatic progression has been a major barrier to rational development of effective therapeutics and prognostic diagnostics for melanoma patients. In this study, we conducted global genomic characterization of primary and metastatic melanomas to examine the genomic landscape associated with metastatic progression. In addition to uncovering three genomic subclasses of metastastic melanomas, we delineated 39 focal and recurrent regions of amplification and deletions, many of which encompassed resident genes that have not been implicated in cancer or metastasis. To identify progression-associated metastasis gene candidates, we applied a statistical approach, Integrative Genome Comparison (IGC), to define 32 genomic regions of interest that were significantly altered in metastatic relative to primary melanomas, encompassing 30 resident genes with statistically significant expression deregulation. Functional assays on a subset of these candidates, including MET, ASPM, AKAP9, IMP3, PRKCA, RPA3, and SCAP2, validated their pro-invasion activities in human melanoma cells. Validity of the IGC approach was further reinforced by tissue microarray analysis of Survivin showing significant increased protein expression in thick versus thin primary cutaneous melanomas, and a progression correlation with lymph node metastases. Together, these functional validation results and correlative analysis of human tissues support the thesis that integrated genomic and pathological analyses of staged melanomas provide a productive entry point for discovery of melanoma metastases genes
Metastatic breast cancer: the potential of miRNA for diagnosis and treatment monitoring
Breast cancer affects approximately 12 % women worldwide and results in 14 % of all cancer-related fatalities. Breast cancer is commonly categorized into one of four main subtypes (luminal A, luminal B, human epidermal growth factor receptor 2 (HER2) positive and basal), indicating molecular characteristics and informing treatment regimes. The most severe form of breast cancer is metastasis, when the tumour spreads from the breast tissue to other parts of the body. Significantly, the primary tumour subtype affects rates and sites of metastasis. Currently, up to 5 % of patients present with incurable metastasis, with an additional 10–15 % of patients going on to develop metastasis within 3 years of diagnosis. MicroRNAs (miRNAs) are short 21–25 long nucleotides that have been shown to significantly affect gene expression. Currently, >2000 miRNAs have been identified and significantly, specific miRNAs have been found associated with diseases states. Importantly, miRNAs are found circulating in the blood, presenting an opportunity to use these circulating disease-related miRNAs as biomarkers. Clearly, the identification of circulating miRNA specific to metastatic breast cancer presents a unique opportunity for early disease identification and for monitoring disease burden. Currently however, few groups have identified miRNA associated with metastatic breast cancer. Here, we review the literature surrounding the identification of metastatic miRNA in breast cancer patients, highlighting key areas where miRNA biomarker discovery could be beneficial, identifying key concepts, recognizing critical areas requiring further research and discussing potential problems
Cardiovascular disease, chronic kidney disease, and diabetes mortality burden of cardiometabolic risk factors from 1980 to 2010: a comparative risk assessment
Background High blood pressure, blood glucose, serum cholesterol, and BMI are risk factors for cardiovascular
diseases and some of these factors also increase the risk of chronic kidney disease and diabetes. We estimated mortality from cardiovascular diseases, chronic kidney disease, and diabetes that was attributable to these four
cardiometabolic risk factors for all countries and regions from 1980 to 2010.
Methods We used data for exposure to risk factors by country, age group, and sex from pooled analyses of populationbased health surveys. We obtained relative risks for the eff ects of risk factors on cause-specifi c mortality from metaanalyses
of large prospective studies. We calculated the population attributable fractions for- each risk factor alone,
and for the combination of all risk factors, accounting for multicausality and for mediation of the eff ects of BMI by the other three risks. We calculated attributable deaths by multiplying the cause-specifi c population attributable fractions by the number of disease-specifi c deaths. We obtained cause-specifi c mortality from the Global Burden of Diseases, Injuries, and Risk Factors 2010 Study. We propagated the uncertainties of all the inputs to the fi nal estimates.
Findings In 2010, high blood pressure was the leading risk factor for deaths due to cardiovascular diseases, chronic kidney disease, and diabetes in every region, causing more than 40% of worldwide deaths from these diseases; high BMI and glucose were each responsible for about 15% of deaths, and high cholesterol for more than 10%. After
accounting for multicausality, 63% (10\ub78 million deaths, 95% CI 10\ub71\u201311\ub75) of deaths from these diseases in 2010 were attributable to the combined eff ect of these four metabolic risk factors, compared with 67% (7\ub71 million deaths,
6\ub76\u20137\ub76) in 1980. The mortality burden of high BMI and glucose nearly doubled from 1980 to 2010. At the country
level, age-standardised death rates from these diseases attributable to the combined eff ects of these four risk factors
surpassed 925 deaths per 100 000 for men in Belarus, Kazakhstan, and Mongolia, but were less than 130 deaths per 100 000 for women and less than 200 for men in some high-income countries including Australia, Canada, France,
Japan, the Netherlands, Singapore, South Korea, and Spain.
Interpretation The salient features of the cardiometabolic disease and risk factor epidemic at the beginning of
the 21st century are high blood pressure and an increasing eff ect of obesity and diabetes. The mortality burden
of cardiometabolic risk factors has shifted from high-income to low-income and middle-income countries. Lowering
cardiometabolic risks through dietary, behavioural, and pharmacological interventions should be a part of the globalresponse to non-communicable diseases
Lawson criterion for ignition exceeded in an inertial fusion experiment
For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion
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