Surface N balances and reactive N loss to the environment from global intensive agricultural production systems for the period 1970-2030

Data for the historical years 1970 and 1995 and the FAO-Agriculture Towards 2030 projection are used to calculate N inputs (N fertilizer, animal manure, biological N fixation and atmospheric deposition) and the N export from the field in harvested crops and grass and grass consumption by grazing animals. In most industrialized countries we see a gradual increase of the overall N recovery of the intensive agricultural production systems over the whole 1970-2030 period. In contrast, low N input systems in many developing countries sustained low crop yields for many years but at the cost of soil fertility by depleting soil nutrient pools. In most developing countries the N recovery will increase in the coming decades by increasing efficiencies of N use in both crop and livestock production systems. The surface balance surplus of N is lost from the agricultural system via different pathways, including NH3 volatilization, denitrification, N2O and NO emissions, and nitrate leaching from the root zone. Global NH3-N emissions from fertilizer and animal manure application and stored manure increased from 18 to 34 Tg·yr-1 between 1970 and 1995, and will further increase to 44 Tg·yr-1 in 2030. Similar developments are seen for N2O-N (2.0 Tg·yr-1 in 1970, 2.7 Tg·yr-1 in 1995 and 3.5 Tg·yr-1 in 2030) and NO-N emissions (1.1 Tg·yr-1 in 1970, 1.5Tg·yr-1 in 1995 and 2.0 Tg·yr-1 in 2030).     

Predicting soils and environmental impacts associated with switchgrass for bioenergy production: a DAYCENT modeling approach

Switchgrass (Panicum virgatum L.) production has the potential to improve soils and the environment. However, little is known about the long‐term future assessment of soil and environmental impacts associated with switchgrass production. In this study, soil organic carbon (SOC), soil nitrate (), water‐filled pore space (WFPS), carbon dioxide (CO₂) and nitrous oxide (N₂O) fluxes, and biomass yield from switchgrass field were predicted using DAYCENT models for 2016 through 2050. Measured data for model calibration and validation at this study site managed with nitrogen fertilization rates (N rates) (low, 0 kg N ha^?1; medium, 56 kg N ha^?1; and high, 112 kg N ha^?1) and landscape positions (shoulder and footslope) for switchgrass production were collected from the previously published studies. Modeling results showed that the N fertilization can enhance SOC and soil NO₃^?, but increase soil N₂O and CO₂ fluxes. In this study, medium N fertilization was the optimum rate for enhancing switchgrass yield and reducing negative impact on the environment. Footslope position can be beneficial for improving SOC, , and yield, but contribute higher greenhouse gas (GHG) emissions compared to those of the shoulder. An increase in temperature and decrease in precipitation (climate scenarios) may reduce soil , WFPS, and N₂O flux. Switchgrass production can improve and maintain SOC and , and reduce N₂O and CO₂ fluxes over the predicted years. These findings indicate that switchgrass could be a sustainable bioenergy crop on marginally yielding lands for improving soils without significant negative impacts on the environment in the long run.     

The Niemann-Pick C1 protein in recycling endosomes of presynaptic nerve terminals

Niemann-Pick type C (NPC) disease is a fatal, neurodegenerative disorder caused in 95% of cases by loss of function of NPC1, a ubiquitous endosomal transmembrane protein. A biochemical hallmark of NPC deficiency is cholesterol accumulation in the endocytic pathway. Although cholesterol trafficking defects are observed in all cell types, neurons are the most vulnerable to NPC1 deficiency, suggesting a specialized function for NPC1 in neurons. We investigated the subcellular localization of NPC1 in neurons to gain insight into the mechanism of action of NPC1 in neuronal metabolism. We show that NPC1 is abundant in axons of sympathetic neurons and is present in recycling endosomes in presynaptic nerve terminals. NPC1 deficiency causes morphological and biochemical changes in the presynaptic nerve terminal. Synaptic vesicles from Npc1(-/-) mice have normal cholesterol content but altered protein composition. We propose that NPC1 plays a previously unrecognized role in the presynaptic nerve terminal and that NPC1 deficiency at this site might contribute to the progressive neurological impairment in NPC disease.     

Metabolomic Derangements Are Associated with Mortality in Critically Ill Adult Patients

Objective

To identify metabolomic biomarkers predictive of Intensive Care Unit (ICU) mortality in adults.

Rationale

Comprehensive metabolomic profiling of plasma at ICU admission to identify biomarkers associated with mortality has recently become feasible.

Methods

We performed metabolomic profiling of plasma from 90 ICU subjects enrolled in the BWH Registry of Critical Illness (RoCI). We tested individual metabolites and a Bayesian Network of metabolites for association with 28-day mortality, using logistic regression in R, and the CGBayesNets Package in MATLAB. Both individual metabolites and the network were tested for replication in an independent cohort of 149 adults enrolled in the Community Acquired Pneumonia and Sepsis Outcome Diagnostics (CAPSOD) study.

Results

We tested variable metabolites for association with 28-day mortality. In RoCI, nearly one third of metabolites differed among ICU survivors versus those who died by day 28 (N = 57 metabolites, p<.05). Associations with 28-day mortality replicated for 31 of these metabolites (with p<.05) in the CAPSOD population. Replicating metabolites included lipids (N = 14), amino acids or amino acid breakdown products (N = 12), carbohydrates (N = 1), nucleotides (N = 3), and 1 peptide. Among 31 replicated metabolites, 25 were higher in subjects who progressed to die; all 6 metabolites that are lower in those who die are lipids. We used Bayesian modeling to form a metabolomic network of 7 metabolites associated with death (gamma-glutamylphenylalanine, gamma-glutamyltyrosine, 1-arachidonoylGPC(20:4), taurochenodeoxycholate, 3-(4-hydroxyphenyl) lactate, sucrose, kynurenine). This network achieved a 91% AUC predicting 28-day mortality in RoCI, and 74% of the AUC in CAPSOD (p<.001 in both populations).

Conclusion

Both individual metabolites and a metabolomic network were associated with 28-day mortality in two independent cohorts. Metabolomic profiling represents a valuable new approach for identifying novel biomarkers in critically ill patients.     

Decline of FoxP3+ Regulatory CD4 T Cells in Peripheral Blood of Children Heavily Exposed to Malaria

FoxP3+ regulatory CD4 T cells (T_regs) help to maintain the delicate balance between pathogen-specific immunity and immune-mediated pathology. Prior studies suggest that T_regs are induced by P. falciparum both in vivo and in vitro; however, the factors influencing T_reg homeostasis during acute and chronic infections, and their role in malaria immunopathogenesis, remain unclear. We assessed the frequency and phenotype of T_regs in well-characterized cohorts of children residing in a region of high malaria endemicity in Uganda. We found that both the frequency and absolute numbers of FoxP3+ T_regs in peripheral blood declined markedly with increasing prior malaria incidence. Longitudinal measurements confirmed that this decline occurred only among highly malaria-exposed children. The decline of T_regs from peripheral blood was accompanied by reduced in vitro induction of T_regs by parasite antigen and decreased expression of TNFR2 on T_regs among children who had intense prior exposure to malaria. While T_reg frequencies were not associated with protection from malaria, there was a trend toward reduced risk of symptomatic malaria once infected with P. falciparum among children with lower T_reg frequencies. These data demonstrate that chronic malaria exposure results in altered T_reg homeostasis, which may impact the development of antimalarial immunity in naturally exposed populations.     

Differential effects of NgCAM and N-cadherin on the development of axons and dendrites by cultured hippocampal neurons

A fundamental step in neuronal development is the acquisition of a polarized form, with distinct axons and dendrites. Although the ability to develop a polarized form appears to be largely an intrinsic property of neurons, it can be influenced by environmental cues. For example, in cell cultures substrate and diffusible factors can enhance and orient axonal development. In this study we examine the effects of growth on each of two cell adhesion molecules (CAMs), NgCAM and N-cadherin, on the development of polarity by cultured hippocampal neurons. We find that although the same pattern of development occurs on control substrates and the CAMs, the CAMs greatly accelerate the rate and extent of development of axons—axons form sooner and grow longer on the CAMs than on the control substrate. In contrast, the CAMs have opposite effects on dendritic development—N-cadherin enhances, but NgCAM reduces dendritic growth compared to control. These results provide further evidence that the development of polarity is largely determined by a cell-autonomous program, but that environmental cues can independently regulate axonal and dendritic growth.     

Efficacy of hyaluronic acid binding assay in selecting motile spermatozoa with normal morphology at high magnification

Background  

The present study aimed to evaluate the efficacy of the hyaluronic acid (HA) binding assay in the selection of motile spermatozoa with normal morphology at high magnification (8400x).