Projecting global biological N fixation under climate warming across land and ocean.

Biological N fixation sustains the global inventory of nitrogenous nutrients essential for the productivity of terrestrial and marine ecosystems. Like most metabolic processes, rates of biological N fixation vary strongly with temperature, making it sensitive to climate change, but a global projection across land and ocean is lacking. Here we use compilations of field and laboratory measurements to reveal a relationship between N fixation rates and temperature that is similar in both domains despite large taxonomic and environmental differences.

Diurnally dynamic iron allocation promotes N fixation in marine dominant diazotroph .

is the dominant photoautotrophic dinitrogen (N) fixer (diazotroph) in the ocean. Iron is an important factor limiting growth of marine diazotrophs including mainly because of high iron content of its N-fixing enzyme, nitrogenase. However, it still lacks a quantitative understanding of how dynamic iron allocation among physiological processes acts to regulate growth and N fixation in .

Phosphate limitation intensifies negative effects of ocean acidification on globally important nitrogen fixing cyanobacterium.

Growth of the prominent nitrogen-fixing cyanobacterium Trichodesmium is often limited by phosphorus availability in the ocean. How nitrogen fixation by phosphorus-limited Trichodesmium may respond to ocean acidification remains poorly understood. Here, we use phosphate-limited chemostat experiments to show that acidification enhanced phosphorus demands and decreased phosphorus-specific nitrogen fixation rates in Trichodesmium.

Assessment of Explicit Representation of Dynamic Viral Processes in Regional Marine Ecological Models.

Viruses, the most abundant microorganisms in the ocean, play important roles in marine ecosystems, mainly by killing their hosts and contributing to nutrient recycling. However, in models simulating ecosystems in real marine environments, the virus-mediated mortality (VMM) rates of their hosts are implicitly represented by constant parameters, thus ignoring the dynamics caused by interactions between viruses and hosts. Here, we construct a model explicitly representing marine viruses and the VMM rates of major hosts, heterotrophic bacteria, and apply it to two sites in the oligotrophic North Pacific and the more productive Arabian Sea.

N Fixation in Does Not Require Spatial Segregation from Photosynthesis.

The dominant marine filamentous N fixer, , conducts photosynthesis and N fixation during the daytime. Because N fixation is sensitive to O, some previous studies suggested that spatial segregation of N fixation and photosynthesis is essential in . However, this hypothesis conflicts with some observations where all the cells contain both photosystems and the N-fixing enzyme nitrogenase.

A Competitive Advantage of Middle-Sized Diatoms From Increasing Seawater CO.

Diatoms, one of the most important phytoplankton groups, fulfill their carbon demand from seawater mainly by obtaining passively diffused carbon dioxide (CO) and/or actively consuming intracellular energy to acquire bicarbonate (HCO ). An anthropogenically induced increase in seawater CO reduces the HCO requirement of diatoms, potentially saving intracellular energy and benefitting their growth. This effect is commonly speculated to be most remarkable in larger diatoms that are subject to a stronger limitation of CO supply because of their smaller surface-to-volume ratios.

Diverse Subclade Differentiation Attributed to the Ubiquity of High-Light-Adapted Clade II.

is the key primary producer in marine ecosystems, and the high-light-adapted clade II (HLII) is the most abundant ecotype. However, the genomic and ecological basis of HLII in the marine environment has remained elusive. Here, we show that the ecologically coherent subclade differentiation of HLII corresponds to genomic and ecological characteristics on the basis of analyses of 31 different strains of HLII, including 12 novel isolates.

Reduced nitrogenase efficiency dominates response of the globally important nitrogen fixer Trichodesmium to ocean acidification.

The response of the prominent marine dinitrogen (N)-fixing cyanobacteria Trichodesmium to ocean acidification (OA) is critical to understanding future oceanic biogeochemical cycles. Recent studies have reported conflicting findings on the effect of OA on growth and N fixation of Trichodesmium. Here, we quantitatively analyzed experimental data on how Trichodesmium reallocated intracellular iron and energy among key cellular processes in response to OA, and integrated the findings to construct an optimality-based cellular model.

Contribution of structural recalcitrance to the formation of the deep oceanic dissolved organic carbon reservoir.

The origin of the recalcitrant dissolved organic carbon (RDOC) reservoir in the deep ocean remains enigmatic. The structural recalcitrance hypothesis suggests that RDOC is formed by molecules that are chemically resistant to bacterial degradation. The dilution hypothesis claims that RDOC is formed from a large diversity of labile molecules that escape bacterial utilization due to their low concentrations, termed as RDOC .

Neuregulin-1 Promotes Myocardial Angiogenesis in the Rat Model of Diabetic Cardiomyopathy.

Background/aims: Microvascular insufficiency takes a critical role in the development of diabetic cardiomyopathy (DCM). So this study was designed to investigate the effects of Neuregulin-1 (NRG-1) treatment on myocardial angiogenesis and the changes of VEGF/Flk1 and Ang-1/Tie-2 signaling in the rat model of DCM.

Methods: Diabetic rats were induced by a single intraperitoneal injection of Streptozotocin.

The complex effects of ocean acidification on the prominent N-fixing cyanobacterium .

Acidification of seawater caused by anthropogenic carbon dioxide (CO) is anticipated to influence the growth of dinitrogen (N)-fixing phytoplankton, which contribute a large fraction of primary production in the tropical and subtropical ocean. We found that growth and N-fixation of the ubiquitous cyanobacterium decreased under acidified conditions, notwithstanding a beneficial effect of high CO Acidification resulted in low cytosolic pH and reduced N-fixation rates despite elevated nitrogenase concentrations. Low cytosolic pH required increased proton pumping across the thylakoid membrane and elevated adenosine triphosphate production.

Very Long-term Outcomes and Predictors of Percutaneous Coronary Intervention with Drug-eluting Stents Versus Coronary Artery Bypass Grafting for Patients with Unprotected Left Main Coronary Artery Disease.

Background: There are limited data on longer-term outcomes (>5 years) for patients with unprotected left main coronary artery (ULMCA) disease who underwent percutaneous coronary intervention (PCI) in the drug-eluting stents (DES) era. This study aimed at comparing the long-term (>5 years) outcomes of patients with ULMCA disease underwent PCI with DES and coronary artery bypass grafting (CABG) and the predictors of adverse events.

Methods: All consecutive patients with ULMCA disease treated with DES implantation versus CABG in our center, between January 2003 and July 2009, were screened for analyzing.

Comment on "Dilution limits dissolved organic carbon utilization in the deep ocean".

Arrieta et al. (Reports, 17 April 2015, p. 331) propose that low concentrations of labile dissolved organic carbon (DOC) preclude prokaryotic consumption of a substantial fraction of DOC in the deep ocean and that this dilution acts as an alternative mechanism to recalcitrance for long-term DOC storage.

Predictive Ability of the SYNergy Between Percutaneous Coronary Intervention with TAXus and Cardiac Surgery Score II for Long-term Mortality in Patients with Three-vessel Coronary Artery Disease Undergoing Percutaneous Coronary Intervention Treated with Second-generation Drug-eluting Stents.

Background: The SYNergy between percutaneous coronary intervention with TAXus and cardiac surgery Score II (SS-II) can well predict 4-year mortality in patients with complex coronary artery disease (CAD), and guide decision-making between coronary artery bypass graft surgery and percutaneous coronary intervention (PCI). However, there is lack of data regarding the utility of the SS-II in patients with three-vessel CAD undergoing PCI treated with second-generation drug-eluting stents (DES). The purpose of the present study was to evaluate the ability of the SS-II to predict long-term mortality in patients with three-vessel CAD undergoing PCI with second-generation DES.

[Coronary artery bypass grafting for elderly with unprotected left main coronary artery disease: a clinical analysis].

Objective: To study the correlation between the clinical features and the prognosis in elderly patients with unprotected left main coronary artery disease (ULMCA) after coronary artery bypass grafting (CABG).

Methods: The clinical parameters and prognosis data from 176 patients received CABG for ULM were retrospectively analyzed for comparison of elderly (age≥65) and against non-elderly (age < 65).

Results: The elderly patients were found to have significantly higher level of blood high density lipoprotein cholesterin (HDL-C, mmol/L: 28.

Syntax score predicts clinical outcome in patients with three-vessel coronary artery disease undergoing percutaneous coronary intervention.

Background: The Syntax score was recently developed as a comprehensive, angiographic tool grading the complexity of coronary artery disease (CAD). It aims to assist in patient selection and risk stratification of patients with extensive CAD undergoing revascularization. However, the prognostic value of the Syntax score in patients undergoing percutaneous coronary intervention (PCI) has not been validated.

[Angiographic characteristics and long term clinical outcomes post coronary stenting in non-diabetic and type 2 diabetic patients with coronary artery disease].

Objective: To observe the angiographic characteristics and the long-term clinical outcomes following coronary stenting in non-diabetic (non-DM) and type 2 diabetic (DM) patients with coronary artery disease.

Methods: This cohort study enrolled 1172 consecutive patients with coronary heart disease underwent elective coronary stenting (249 type 2 DM and 923 non-DM). The angiographic characteristics and the long-term clinical follow-up results were compared between non-DM and DM patients.